Old, New guy, with Old Problems

[Ripsaw]

Hello all, First post here, regrettably so. This is a last ditch desperation move to join a forum and come here for help....Why ? Because of my pride as a man. I am 58 years old, and was raised to handle all problems myself, and never ask for anything from anyone. So you can see this is tough for a guy like me. But I must swallow my pride and ask for help.

I have a 1991 C1500 Silverado Pick-up truck. I have searched high and low on the net for the fix on my problem. The truck has 211,000 miles and has been very well taken care of. Oil changed every 3,000 miles for life, all highway miles. All filters too. Never had a problem till the fuel pump quite. I replaced it and the filter on the end.....on the road again !

Rocked on for several thousand miles after that with no troubles....then one day it died at a redlight, cranked right back, but I noticed is was idling lower than normal and was cycling between 600-800 RPM's on the tacometer, I noticed the idle would start surging up and down, then eventually, it would not idle and die, if I didn't keep gassing it.

Now for some history.....my pride.... I grew up with a Dad that raced with A.J. Foyt back in the day on the roundy rounders...dirt trackin it....we did all our own builds and work. So I am by no means clueless.....enter my pride and past life experiences for problem solving. But I am a carb guy, and knew nothing about TBI's....or computer crap either. So I did some searching and bought and replaced the idle air control valve, got it up to 45 MPH to reset it as per instructions. Then I replaced the PCV valve and the Coolant temperature sensor, oxygen sensor, and checked all the wires for grounding out somewhere, and for vacuum leaks anywhere. Found a couple of slight leaks in vacuum hoses and repaired those too. All new plug wires and plugs, cap and rotor.

I found a wiring diagram for the injectors in the TB, and have learned the red and white leads, one from each injector, goes to the EGR Solenoid, whatever in the heck that is,...or does....Help for that? And, I found the green and blue go to ground. I learned how to check the power to each from the EGR with a light, and have heard that if any wire is grounded out, it will cause the injectors to flood and pour fuel. That is what is happening, they are pouring, not spraying, and it is continual and will not crank or run now. I bought a rebuild kit, checked injectors, they are good, and rebuilt the entire TB.

I also installed new timing chain and gears because at first, it all acted like a timing problem, back firing and all sorts of crazy stuff. Then I got back to searching for answers. I came across a post on a forum where a guy had the same problem as me. ( Actually hundreds and hundreds of guys are having the same problem, with no solutions after changing everything).... He replaced everything, still no joy. Finally, he had a mechanic buddy tell him that there is a pick-up coil in the distributor, just under the rotor and below the vacuum advance assembly. If that coil goes bad, as his did at 177,000 miles, it will flood the injectors. He also said that the module and the pick-up coil on the distributor, in unison with the MAP sensor and throttle positioning sensor, is what tells the injectors to pulse, and how much....if it's bad , they flood.

Now the weird part. After installing the timing chain and gears, and getting ready to bust it off after building the TB, I got the timing mark to spec called for on the harmonic balancer, checked number one for TDC with plug pulled and long screwdriver and moved it back and forth to make sure it was topped out, then pulled the distributor cap. The rotor was facing 180 degrees out from number one ! Keep in mind, I never pulled the distributor to install timing components, and only a complete idiot could screw that up when attaching new gears. The crank has a keyway, and the cam has a nipple and three bolts. The timing gears have a dimple for 6 and 12 O'clock....it can only work one way. Mine was right. So I am completly bumfuzzled now.

So I think about it awhile, and decide to try it anyway. My wife got in, turned the key, and it still kept flooding. I turned the distributor back and forth, and had it running for a moment, albeit badly because of the flooding. Then it died and backfired a little, just fuel, no fire out the TBI. So I sent her back inside to scratch my head awhile. Then I decide, the gear on the bottom of the distributor must be bad, for the rotor to be out 180. But the slot for the oil pump won't allow that without a broken shaft on the distributor.... Right ?
So before pulling it, I decided to move all the wires to the firing order to match up with the right cylinder...no joy, wouldn't crank, big surprise.

So I quit for the day. Go back out the next day, move wires where they go, went through the whole timing procedure again...done it a thousand times in my life. Pop the cap to check the rotor...and holy moley...it is back on number one with timing mark lined up and cylinder up. What the heck ???? So now I know it has to be the gear at the bottom of the shaft is screwy. I pull the distributor....nope....it is fine, no sheared pin, no gear damage from cam being bad either. So I am totally freaked out now....so freaked out in fact, that I forget to stick a screwdriver in the oil slot and try to turn the rotor to see if shaft is broken like in a stair step across, so it could be jumping up and over, then back again. Then I realize that if that was the case, the rotor would have raised up and damaged the contact points in the cap, no damage there either BTW. I restabbed the distributor....no joy, no cranking....one freakin problem at a time I decide. I have to stop the injectors from flooding. But how did the rotor get 180 off and correct itself ? Have I gone senile I think to myself. What am I missing guys ? I use to be a good mechanic,..what happened ?

I did not want to keep throwing money at this until I find it, I am a 100% disabled vet and really don't have it to throw, it is not service connected, so I have a minimum pension of $378 a month. Next is the MAP sensor and TPS, The EGR Solenoid, then maybe a distributor....depending on what you guys think ? That's another 200 bucks ! I hear something called the ECU is involved also....couldn't tell you where it is or what it does, or even what the letters stand for, but I do know it is expensive. BTW, new injectors, in case my test were wrong, are $135 each....another 270 bucks, and the only thing not new in the TB.

Sure could use some help ? Ideas, reflections, suggestions or tips....welcome in this thread....... Best regards.....Rip.

[ChevyTech]

Welcome to the board!

As for the engine timing:

If when you put the new timing chain in, you line up the timing marks on the crank gear and cam gear the same as it was when you took it apart, everything should have been good with the distributor.

If the dots on the gears are pointing at each other the the distributor rotor should point to cylinder #6 plug wire.
If both dots are pointing up then the distributor should point to #1 plug wire.

When you check in the spark plug hole with a screw driver and get the piston at the top, you don't know if it is at the compression stock so the distributor should point at #1, or if it is at the top of the exhaust stoke so the distributor should point at #6.


To get the engine back in time:
Remove the number one spark plug.
Turn the engine until you can feel compression coming out the number one spark plug hole.
Continue to rotate the engine slowly until the timing mark on the front balancer is lined up.
Note: sometimes the outer ring on GM engines slips and makes the timing mark inaccurate.
Mark the position on the distributor housing that lines up with the number one wire on the distributor cap.
Install the distributor with the rotor pointing to the number one wire position when the distributor is fully seated.

[ChevyTech]

As for the injectors spraying to much fuel:

This sounds like a bad coolant sensor, but there are two coolant sensors.

The coolant sensor in the cylinder head is for the instrument panel gauge / light.

The coolant sensor in the intake manifold next to the thermostat is for the computer, and this sensor determines how much fuel the injectors will spray. If the connections are not tight or corroded it can cause it to spray to much fuel just like the sensor is bad.

Post 11 in this thread has instructions for testing the coolant sensor for the computer:
http://67-72chevytrucks.com/vboard/s...d.php?t=379142

When the key is on there should be power to the injectors and the computer grounds the other side of the injectors to make them spray.

The EGR solenoid has nothing to do with the injectors.

Sometimes the injectors wires get rubbed through insulation by the TBI unit and the big collar that sits between the TBI and the air cleaner. Make sure there are no bare wires.

[ChevyTech]

ECU (Electronic Control Unit) = ECM (Electronic Control Module) what General Motors called it in that time frame. It is the computer that is mounted inside the truck behind and below the glove box.

The ECM is not a common failure part.

Another thing to look at for being to rich is to make sure the vacuum is getting to the MAP (Manifold Absolute Pressure) sensor, but this should not affect the mixture during engine cranking and should only have affect once the engine is running.

The engine surging up and down sounds like low fuel pressure, but there are other items on TBI trucks that can cause low pressure other then the fuel pump.

If the fuel pressure regulator spring inside the TBI unit breaks the fuel pressure will be low even with a new pump. Did you replace the short hose in the tank when you put a new pump in. It is common for the hose to split and lose all the fuel pressure into the tank.

Post #17 has a photo of a broken fuel pressure regulator spring. The rest of this thread may help too.
http://67-72chevytrucks.com/vboard/s...d.php?t=347247


Here is a link to the two pages of the common Frequently asked question for trucks in this section. You may find a lot of helpful information there.
http://67-72chevytrucks.com/vboard/s...=445487&page=2

http://67-72chevytrucks.com/vboard/s...d.php?t=445487

Checking for trouble codes without a scan tool:
http://67-72chevytrucks.com/vboard/s...5&postcount=11


Don't buy any more parts until we talk more.

[Ripsaw]

Thanks so much Chevy Tech, I won't. I will "pour" over this info tomorrow first before doing anything. Pardon the pun.... heh heh heh... Problem has me sleepless now. I appreciate all the links and info. Will keep you posted of developements. Best Regards.....Rip.

[Ripsaw]

Originally Posted by ChevyTech

Welcome to the board!

As for the engine timing:

If when you put the new timing chain in, you line up the timing marks on the crank gear and cam gear the same as it was when you took it apart, everything should have been good with the distributor.

If the dots on the gears are pointing at each other the the distributor rotor should point to cylinder #6 plug wire.
If both dots are pointing up then the distributor should point to #1 plug wire.

When you check in the spark plug hole with a screw driver and get the piston at the top, you don't know if it is at the compression stock so the distributor should point at #1, or if it is at the top of the exhaust stoke so the distributor should point at #6.


To get the engine back in time:
Remove the number one spark plug.
Turn the engine until you can feel compression coming out the number one spark plug hole.
Continue to rotate the engine slowly until the timing mark on the front balancer is lined up.
Note: sometimes the outer ring on GM engines slips and makes the timing mark inaccurate.
Mark the position on the distributor housing that lines up with the number one wire on the distributor cap.
Install the distributor with the rotor pointing to the number one wire position when the distributor is fully seated.

Roger that for my senior moment. I realized about the compression stroke at 2 a.m. when I couldn't sleep.

[Ripsaw]

Originally Posted by ChevyTech

As for the injectors spraying to much fuel:

This sounds like a bad coolant sensor, but there are two coolant sensors.

The coolant sensor in the cylinder head is for the instrument panel gauge / light.

The coolant sensor in the intake manifold next to the thermostat is for the computer, and this sensor determines how much fuel the injectors will spray. If the connections are not tight or corroded it can cause it to spray to much fuel just like the sensor is bad.

Post 11 in this thread has instructions for testing the coolant sensor for the computer:
http://67-72chevytrucks.com/vboard/s...d.php?t=379142

When the key is on there should be power to the injectors and the computer grounds the other side of the injectors to make them spray.

The EGR solenoid has nothing to do with the injectors.

Sometimes the injectors wires get rubbed through insulation by the TBI unit and the big collar that sits between the TBI and the air cleaner. Make sure there are no bare wires.

Replaced the proper one, and checked terminals and wires....good to go. Will do test tomorrow if rain quits for the computer.

Will check power again tomorrow on injectors and get back with you.

Injector wires checked for cracks or bareness, all down through the insulated harness and under the bracket, and all the way to the EGR solenoid, they appear good to go and undamaged.

[Ripsaw]

Originally Posted by ChevyTech

ECU (Electronic Control Unit) = ECM (Electronic Control Module) what General Motors called it in that time frame. It is the computer that is mounted inside the truck behind and below the glove box.

The ECM is not a common failure part.

Another thing to look at for being to rich is to make sure the vacuum is getting to the MAP (Manifold Absolute Pressure) sensor, but this should not affect the mixture during engine cranking and should only have affect once the engine is running.

The engine surging up and down sounds like low fuel pressure, but there are other items on TBI trucks that can cause low pressure other then the fuel pump.

If the fuel pressure regulator spring inside the TBI unit breaks the fuel pressure will be low even with a new pump. Did you replace the short hose in the tank when you put a new pump in. It is common for the hose to split and lose all the fuel pressure into the tank.

Post #17 has a photo of a broken fuel pressure regulator spring. The rest of this thread may help too.
http://67-72chevytrucks.com/vboard/s...d.php?t=347247


Here is a link to the two pages of the common Frequently asked question for trucks in this section. You may find a lot of helpful information there.
http://67-72chevytrucks.com/vboard/s...=445487&page=2

http://67-72chevytrucks.com/vboard/s...d.php?t=445487

Checking for trouble codes without a scan tool:
http://67-72chevytrucks.com/vboard/s...5&postcount=11


Don't buy any more parts until we talk more.

No, I did not replace the hose in the tank. Oh lordy.....wasn't aware of this common problem until joining and reading here.

All new guts in the TBI except injectors, including regulator, and new fuel filter in line.

Read all your links, gotta get some sleep. it's only 4:13 A.M, !....try anyway....many thanks again Bud !!

[ChevyTech]

You're welcome.

The coolant sensor is the most common problem causing this system to go very rich.

You replaced the sensor, and checked the connector, but another thing I have not mentioned yet is that the ground for the coolant sensor is under one of the studs at the front of the intake. If the ground has resistance or is broken the system will go very rich.

If your truck has a ground connected at one of the thermostat housing bolts, move that ground to one of the intake studs.

Check all the ground wires at the front of the intake.

[ChevyTech]

I have another test I want you to do.

Have someone turn the key on while you watch the injectors during the 2 second fuel pump prime time and see if fuel comes out of the injector area.

The o-rings can get damaged when the injector are installed.
The aluminum is very thin in the area of the bottom of the injectors and can crack if injectors are forced into the housing without putting lubricant on the o-rings.

You should see no fuel at all during this test.

[Ripsaw]

Originally Posted by ChevyTech

I have another test I want you to do.

Have someone turn the key on while you watch the injectors during the 2 second fuel pump prime time and see if fuel comes out of the injector area.

The o-rings can get damaged when the injector are installed.
The aluminum is very thin in the area of the bottom of the injectors and can crack if injectors are forced into the housing without putting lubricant on the o-rings.

You should see no fuel at all during this test.

Ok Tech, will do,.... I installed them and used ATF as lube, and was very careful, but will test as suggested. Is there any definitive way to check the injectors to make sure they are good themselves. I heard somewhere that you can use a 9 volt battery and wires to tap them at the terminals, and they should click if working, but to not hold the wire to them but a split second. Would 12 volt be too much ? Is that the way to test them ?

heading out in a few minutes as it warms up a little.

Also plan to check:

magnetized shaft on distributor, & for any movement side to side
power to injectors,
pulse to ground on injectors with engine turning over,
ground to temp sensor again,
and should I disconnect the EGR valve vacuum to see if the injectors quite flooding ? ...Yes, I have been reading.....ALOT !

Timing is right,checked it yesterday during compression stroke....Duhh...heh heh heh.

[hyatt]

Over the years have had a LOT of trouble with short hoze in tank Most common problem is split and letting pressure off another is not getting tight on pump replacement and blowing off and third having been replaced with regular fuel line instead of high pressure fuel injection line Symptoms are very similar to your problems and as you said problems all started after pump replacement

[Ripsaw]

Originally Posted by hyatt

Over the years have had a LOT of trouble with short hoze in tank Most common problem is split and letting pressure off another is not getting tight on pump replacement and blowing off and third having been replaced with regular fuel line instead of high pressure fuel injection line Symptoms are very similar to your problems and as you said problems all started after pump replacement

Thanks Hyatt, I read that too. I will check it now. Thanks for reminding me again. I left it out of my list of checks above, after Tech already told me. I can't remember anything anymore if I don't write it down.

[ChevyTech]

Don't connect wires or power to your injectors.
If it is flooding and no gas leaks when you do a key on observation test, but floods when you try to start it the injectors are opening.

If the engine is flooding, but no gas drips with the key for the pump prime without cranking the engine, then:
The EGR will not cause the injector to dump in a lot of fuel.
The injectors are getting power and ground.
If the engine is flooding don't worry about a split hose in the tank for now - it is getting fuel.
No need to check for injector pulse unless you have a “NOID” light to test it, but there is a problem elsewhere.

If you have a problem in the distributor that caused no signal to the ECM, then the ECM would not pulse the injectors to let any fuel into the engine.

It is always ok to disconnect the vacuum hose to the EGR for a quick test.

If the truck has good strong spark, and is getting to much fuel injected it is almost always because of the COOLANT SENSOR or the wiring for the coolant sensor or its ground.

If you flooded it, and have not cleaned the spark plugs, the plugs could be so wet that it will not start.

If the IAC (Idle Air Control) does not work these trucks tend to flood when trying to start them. Holding the gas pedal to the floor will put the ECM in a clear flood mode, if the TPS works, and stop any fuel from being injected while the gas pedal is held to the floor.

To clear gas from a flooded engine you can just unplug the injectors, so no fuel can be injected, and then try to start the engine.

[ChevyTech]

Let's make sure I understand where things are at right now.

The truck will not start, correct?

The injectors are spraying in a lot of fuel, correct?

Have you made sure there is a good hot blue spark that will jump at least ½ inch?

Are the spark plugs wet with fuel? Are the spark plugs all black & wet?

[Ripsaw]

Originally Posted by ChevyTech

Don't connect wires or power to your injectors.
If it is flooding and no gas leaks when you do a key on observation test, but floods when you try to start it the injectors are opening.

Key observation test negative, no fuel or dripping

If the engine is flooding, but no gas drips with the key for the pump prime without cranking the engine, then:
The EGR will not cause the injector to dump in a lot of fuel.
The injectors are getting power and ground.
If the engine is flooding don't worry about a split hose in the tank for now - it is getting fuel.
No need to check for injector pulse unless you have a “NOID” light to test it, but there is a problem elsewhere.

If you have a problem in the distributor that caused no signal to the ECM, then the ECM would not pulse the injectors to let any fuel into the engine.

It is always ok to disconnect the vacuum hose to the EGR for a quick test.

If the truck has good strong spark, and is getting to much fuel injected it is almost always because of the COOLANT SENSOR or the wiring for the coolant sensor or its ground.

If you flooded it, and have not cleaned the spark plugs, the plugs could be so wet that it will not start.

If the IAC (Idle Air Control) does not work these trucks tend to flood when trying to start them. Holding the gas pedal to the floor will put the ECM in a clear flood mode, if the TPS works, and stop any fuel from being injected while the gas pedal is held to the floor.

To clear gas from a flooded engine you can just unplug the injectors, so no fuel can be injected, and then try to start the engine.

Pulled all plugs, black and some wet, burned with my zippo, and reinstalled. unplugged injectors all on my own to attempt starting again....orange you proud ?

Originally Posted by ChevyTech

Let's make sure I understand where things are at right now.

The truck will not start, correct?
yes

The injectors are spraying in a lot of fuel, correct?
yes

Have you made sure there is a good hot blue spark that will jump at least ½ inch?

I reckon so, it knocked me for a loop....haaa haa, was trying to ground coil wire with a screwdriver, and was touching something....Wham ! It works, trust me.

Are the spark plugs wet with fuel? Are the spark plugs all black & wet?
Yep.

Ok, latest update.......Moved the ground for coolant temp sensor to the same stud as the battery ground on the intake, from the thermostat housing, then got to thinking about something I read from all your links you gave me. I had an old module for the distributor in my 89 Silverado that I had replaced when I had a previous starter problem. Some vehicles won't do anything when you turn the key if module is bad, so I assumed it was that,...tried hot test at starter and realized it was bad....so anyway, I had a spare mod. I read that it has something to do with the pulse to the injectors I thought, so I put it in my 91. I screwed up though, because I changed two things without checking the first by cranking it over, and now I will never know which it was......

BUT IT BUSTED RIGHT OFF !!!!!!....NO FLOODING INJECTORS,
I had the wife crank, and turned the distributor until it caught and she blew baby !! Running smooth as silk. I am so mad at myself for not checking after changing the ground, but I really think it was the module.

I do not know if this is a bonafide test, or tells us anything, but I ohm'd out the old module at the coil terminals, and it was 60 on the scale, the new one read 20. I checked the pick-up coil wire leads on the dist. for continuity and it read 8 ohms.

But now, I am not sure I set the timing right. I read the schematic you linked me two, or found here, can't remember now I read so much over the past few days, but I found a black plastic hook-up coming out of the junction of the harness, on the passenger side near the firewall, I know the article said brown and tan wire for timing, and to unplug it while setting it, but this appears cream colored or light tan, with what appears to be a black tracer, or could be dark brown.

How can I determine if I unhooked the right wire for timing ?

Anyway, I unplugged it, and had her hold it at 1200 RPM's....(305)...I set it per spec at 0 degrees. It ran fine, turned off, cranked right back.

Went down the road a mile or two, got up to 45, ran fine. Got back, did it again for three miles, as I turned around and slowed down, it died, cranked right back and came home. Then it started getting a little miss or stumble like a plug or wire was bad.

Let it sit awhile and decided to take it on the highway....now the problem I am having and wondering about my timing procedure. When I got up to 50, and called for gas, she stumbled and faultered badly, bucking and jerking, I called hard and opened the gates, but nothing, RPM's steadily decreased. I slowed down and braked, turned it toward home, and she ran fine below 45, good torque and lots of power at slow speed, even kicked the throat once and she lit up....but at higher RPM's,....she's a dog.....

Now what have I screwed up ??????


P.S.....Hey Tech...I know I don't have to say this, but I don't know what I woulda done without your help. Thank you very much......
and thanks to Hyatt also for his response and trying to help ! This place may become my new home so I can try and pay it forward, or try to help others like you guys helped me. It is a noble thing you do.

Now if you could lead me by my little hand....and my pointed little head...and help me figure this bogging down out....I would be much appreciative.

[Ripsaw]

Almost forgot, while I had the cap off, I checked the shaft for magnetized, and it wasn't.

I checked the plate below the rotor, with eight points on it and has four rivets holding it on, where the old type vacuum advance wings and springs would be, and it was magnetized. Also checked for play in the shaft, it wiggles forward to backwards about a full eighth of an inch, but side to side only about a 1/16".

What does that mean ? Good or bad, or indifferent ?

[ChevyTech]

You're welcome and I am glad you arte making progress.

Your distributor is worn. The shaft should not wiggle.

It needs a distributor, but if it still has spark, don't worry about that until you find out what other problems there are.

The timing should be set with the engine at idle. Warm up the engine first. If everything is right it will idle with the set timng wire uplugged, but most of them will just barely idle when trying to setthe timing. When you plug the set timing wire back together the timing should advance at least 12 degrees.

There should be a trouble code stored in the ECM from have the set timing wire unplugged. You can test your knoweldge by seeing if you can read the code without a scan tool.

[Ripsaw]

Originally Posted by ChevyTech

Your distributor is worn. The shaft should not wiggle.

It needs a distributor, but if it still has spark, don't worry about that until you find out what other problems there are.

Roger that, thanks again. I will double check the timing setting tomorrow. And buy another set of plugs, these set awhile since it has been down, so have the wires, lots of rat evidence, so I will change wires too and see if I can get rid of the miss. It is intermitent.

[ChevyTech]

Go read the post above your last post because I was editing while you were posting.

Did you put heat sink compound/grease under the module when you installed it? Without it module failure is likely, very soon.

Part of my instructions from another post:
The set timing wire, which is a single Tan wire with a black stripe/tracer on it.

[hyatt]

Low fuel pressure could still be a problem Dont remember if your engine has a port to check pressure Low pressure would run at lower demand and fade at higher rpm

[ChevyTech]

Originally Posted by hyatt

Low fuel pressure could still be a problem Dont remember if your engine has a port to check pressure Low pressure would run at lower demand and fade at higher rpm

TBI trucks don't have a fuel pressure test port, but I agree there are more problems and low fuel pressure is still a possibility.

[ChevyTech]

As you get this running better there is another thing I am going to have you do, and I would do it before replacing the plugs.

If it is a 305 it has a higher compression ratio then a 350 and carbon build up is bigger problem.

An engine that has run rich and has many miles on it could have heavy carbon deposits. You may want to try “Sea Foam” or GMs “Top Engine cleaner” to remove carbon build up. My experience has been that TBI trucks with high miles usually have a lot of build up on there valves.

I slowly pour in a half can in the HOT engine at fast idle, then shut off the engine and let it sit ten minutes. Then I slowly pour in the rest of the can at a FAST idle, and then go drive it.

I have used SEA FOAM several times with great success. I have also used GMs TOP ENGINE CLEANER at the dealership many times with good results. The GM Top Engine Cleaner smells just like SEA FOAM to me and I have wondered if they are the exact same product. I have never had any problems from using these products, but if an engine has very heavy carbon, one treatment may not get it all out. My biggest concern is that it is not poured in so fast that it liquid locks the engine.

[Ripsaw]

Originally Posted by ChevyTech

You're welcome and I am glad you arte making progress.

Your distributor is worn. The shaft should not wiggle.

It needs a distributor, but if it still has spark, don't worry about that until you find out what other problems there are.

The timing should be set with the engine at idle. Warm up the engine first. If everything is right it will idle with the set timng wire uplugged, but most of them will just barely idle when trying to setthe timing. When you plug the set timing wire back together the timing should advance at least 12 degrees.

There should be a trouble code stored in the ECM from have the set timing wire unplugged. You can test your knoweldge by seeing if you can read the code without a scan tool.

I swear I read somewhere that the timing should be set at 1200rpm's...losin my mind I guess. I thought that was aweful high.

When I did it the way I did, and plugged the set timing wire back in, nothing changed. No rpm change or anything. But that totally explains the bog, I advanced the rpm's and set the timing for idle rpm's....duh...I should know better. Maybe it comes from me being five years old and tagging around behind the old man in the garage as he cleaned parts in a gas pan. To this day, when I get a whiff of gas, I can see 235 cu. inch 6 banger parts.

Paper clip, "potatoe chip".....see, I have been reading......But I really didn't absorb that last part too well....will the code still be stored after I plug it back in, or did you mean while it is unplugged, to determine if it is the right wire?

Thanks for the compound tip, I knew that. It had squashed residual butter on the edges from the previous install on the module, I scaped with knife blade and gathered it and spread it back on the flat. It won't be enough though.

I planned on getting another one, or was hoping someone knew the chemical make-up of the compound, and I could make some home-made and put on it. Do you know what it is made off ?

Spreads and feels like a combination of
latex and silicone caulk, you think that would work ?



Hey bud, it shouldn't be all work and no play, funny story time. When I was twelve years old, I was 6' 2" tall and almost had a beard already. I went walking around the countryside in east Texas where I grew up, near Lufkin in a little community called Redland. I wanted my own truck bad, but had no money, and you know how I was raised. Had to figure it out on my own. So I started mowing lawns to earn and save for one.

An old man that lived down the road watched me mow lawns with a push mower..."Big Lawns"....all day suckers. So one day when I was pushing my mower and walking home, two miles away from my job site that day, I passed his house, it was hot, bad hot, and I was sweating down. He was sitting on the porched and called to me and asked if I wanted to rest and have some tea. I did. He knew my folks well and was our next door neighbor...about a mile away. So anyway, I sat down with him on the porch, and had a glass, and as I was drinking it up, I stared into the high weeds over by his fence line, and saw an old rusted, riding mower, and it was torn apart in a basket case, we called them back then. All the engine parts in a box too, disassembled. I asked about it, he said he tore it apart because it didn't run anymore, and lost interest. It looked it too, his place was bad grown up.

I aksed if he wanted to sell it, because I was sick of push mowing huge jobs. He said yeah, $35 bucks. I had $40, bought it from him and told him I would get my old mans truck and come back for it. Did so the next day.

Got it back and went to work every day afer school on it. Stripped it, painted it red white and blue, cleaned it all up, put it all back together and bought a new seat. Filled it with gas, put a new battery in it, choked it, and it fired right off. For my maiden voyage, I rode it to his house with an extra can of gas, and when I pulled up in his yard, I started cutting his place with it...sort of a thank you gesture. He came running out of his house, and his eyes popped. He said, is that my mower ? I said...it was.

So after I finished cutting, we had some tea on the porch, and while I was cutting beside his old barn, I saw something rust brown, completely grown up behind it, something with glass shining in the sun. While drinking tea, I told him I would have mowed behind the barn, but there was something grown up in there, in my way. He said, that was his old truck, it wasn't any good anymore. I asked if I could look at it, he said sure. I cut for hours with a hay maker, an axe, and my mower, till dusk. I found a 1951 chevy pick-up, with the body in perfect condition, and only surface rust. I really liked those freeway corner windows. The interior was not bad at all either, just needed cleaning. Finally I asked him, would he sell it ? He said....no, but I would trade it to you for my mower back......I said done ! But I need a ride home.
He took me....the next day, I got my brother and a truck and came to tow it home.

Long story short, bought a rebuild kit, busted right off, and that was my first truck.....$35 dollar truck......so that's why I should know better about the 91 timing and rpm's and advance. Just getting old I guess.


Thanks again for the tips...I will foam it after I straighten out the timing and the module butter, and before plugs and wires. Come to think of it, it did sound like valve seat problems, being intermitent like that, had it been plugs or wires, it would have been constant.

I have used a pitcher of ice water to trickle in one all carboned up on the valves......I know, I know....but hey, country boy can survive. It was a Buick Electra 225, 455cu.in. It ran like crap, tuned it up...still like crap. Hit it with ice water and the tail pipes shot fireworks like fourth of July. It ran like a dream after that, put another 100,000 miles on it.

[ChevyTech]

I swear I read somewhere that the timing should be set at 1200rpm's...losin my mind I guess.

Old Oldsmobiles used to be timed at 1100 RPMS.

Paper clip, "potatoe chip".....see, I have been reading......But I really didn't absorb that last part too well....will the code still be stored after I plug it back in, or did you mean while it is unplugged, to determine if it is the right wire?

The code will stay in the memory until 50 engine run cycles or until power is removed from the ECM. A code 42 will get set when the set timing connector is unplugged to set the timing.

Thanks for the compound tip... … I planned on getting another one, or was hoping someone knew the chemical make-up of the compound, and I could make some home-made and put on it. Do you know what it is made off ?

Spreads and feels like a combination of
latex and silicone caulk, you think that would work ?

Do NOT use anything with silicone in it!
The auto parts stores around here sell little packets of heat sink compound separately.