Tbi swap build thread

[rfmaster]

Originally Posted by manimal

OK, here are my findings......
Key off; .01 dcv between dark green/white and black/white
Key in run; 12 dcv, does not go off after 2sec
engine cranking/running; .66 dcv
* accidentally touched the tan/white wire instead of dark green w/DVM engine stalled
I cannot find a fuse link-also my FSM says that is only for the "CK" and not the "RV" vehicles. I am confused.....
I then followed the FSM for the test...
I hooked up 12v power to the FP test wire and pump runs.
disconnected the fuel module and removed the 12v to the test wire..key to run, pump does not run.
key on;checked the orange wire to ground I have 12v, then dark green/white to battery -, I have 12v,but when I use a test light between the two I get nothing????(test light is good) NOW I am really confused!
using the test light proceedure, my manual says there would be an open or short in the dark green/white wire or faulty ECM.
SO I continued on based on the DVM reading of 12v @ the dark green/white wire......
again key in run still no FP running.
Reconnected the fuel module engine running,disconnected the FP relay, engine still ran.
Key off, I probed the FP test socket, no power....Factory Service Manual says-NO TROUBLE FOUND.
Does any of this make sense? Cause I am REALLY confused.
Thank You

Ok lets take it step by step.

1) Take a look at a circuit attached. The RV section is top of the page.
The only major difference between the two is that RV has prime terminal hanging at the end of red wire (under FP relay) and CK have that end terminated at ALDL connector. Otherwise functionally and electrically they are the same.

2) Theory of operation.
Re-install FP relay. Disconnect oil pressure switch connector.
At the oil pressure switch locate orange wire terminal - it must have 12 volts at all times. The fuel pump side may have either tan/white or gray color wire - this is a switched side of FP relay. During POST ECM applies 12 volts at Pin A1 (dark green/wht) energizing FP relay for about 2 seconds. Also at the same time it monitors voltage on pin B2 (Fuel pump signal). FP power-up FP circuit for about 2 seconds and shuts off. This is a normal operation without fuel module.
When you removed FP relay ECM will not see 12 volts pin B2 (Fuel pump signal) which will set DTC 54 (FP voltage low). With DTC 54 set ECM goes into limp mode and depending on calibration it may not apply control signal (A1) during cranking - I simply do not know why, but I have seen this before. What is important is that ECM is able to supply +12 volts to FP relay from pin A1 dark green/wht wire.

Now, with FP relay re-installed connect DVM to measure DC voltage from gray pin of the oil pressure connector to ground. Oil pressure switch is a fail safe mechanism if FP relay fails with engine running. With ign off you should see 0 Vdc, ign into run - you should see 2 sec (with Fuel module disconnected) or 20+ seconds with fuel module connected. During cranking there must be +12 volts.

3) dark green/wht is a low current switched source - supplied by ECM (pin A1). It should not be shorted to ground as it will blow switching transistor inside ECM! Use DVM - do not use test light since you do not know how much current your test light is pulling. Typical FP relay has a coil resistance between 200 and 300 Ohms and pulls less than 100 mA of current from 12V.

4) Take a look at FP test connector (490 red on attached schematic). It is connected to NC contact of FP relay. Under normal conditions, FP relay is powered moving center contact from NC to NO position and with engine running you should 0 volts. If and only if FP relay failed to close and engine is running you will see +12 volts as fuel module or oil pressure switch are supplying power to FP. This way you can establish if you have a flaky FP relay coil or control circuit.

//RF

[68 TT]

Originally Posted by kcblazer75

What do you think the diameter and height of the ring/sump pan would need to be?

Once inside the tank, could you bring the seam you need to weld up to the hole? You could weld it without having to reach all the way inside.

The taller you can make it the better so if you made the ring just a fraction smaller than the diameter of the sender opening that would probably be about 3" tall.

If you made it 6" in diameter the 3" tall sump could hold a little over a 1/3 of a gallon of fuel. That should be enough for a pretty heavy turn while low on gas.

Start with a solid ring and drill a couple 1/4" holes around the perimeter to allow low fuel level sharing with the rest of the tank but not bleed off too quick and defeat the purpose of the sump in the first place.

If you could hard line plumb the return line from the regulator into the side of the sump ring it would almost always have fuel in it.

[manimal]

I just re-read my last post, sorry, I did not mean I grounded the dark green/white wire. I was using the DVM. Black lead to battery ground and red lead to pin A1.
I will go test the oil pressure switch now. But everything I have done thus far, the voltage never shuts off after 2-3 seconds,fuel module connected or not. That is where I am confused.
I am going right now to test the oil switch.
Thank You


BTW should I start my own thread? I feel bad for hijacking this one.

[rfmaster]

Originally Posted by manimal

I just re-read my last post, sorry, I did not mean I grounded the dark green/white wire. I was using the DVM. Black lead to battery ground and red lead to pin A1.
I will go test the oil pressure switch now. But everything I have done thus far, the voltage never shuts off after 2-3 seconds,fuel module connected or not. That is where I am confused.
I am going right now to test the oil switch.
Thank You


BTW should I start my own thread? I feel bad for hijacking this one.

Hmmm. I have never seen ECM not shutting down FP relay. Almost always the opposite - never powering up (due to a bad switching transistor). I have seen my share of bad relays in the past, but stuck and holding and then releasing?!

Regarding a thread - your choice. This thread is a collection of problems and solutions relating to swapping TBI system into early squire body trucks. For conversion I look for 87+ trucks and cars for parts.

I never visit 88+ forum since my rig is 1975.

//RF

[manimal]

OK here are my findings again.
Fuel module connected: oil pressure switch; key off(tan/white didnt have a gray) 0dcv, key on 9.36 dcv for 20sec, cranking 0dcv
Fuel module disconnected; oil pressure switch; key off 0dcv,key on 0dcv,cranking 0dcv
Engine running;fuel module connected; fuel pump test pig tail 12+dcv(actually 13.8dcv)

[rfmaster]

Originally Posted by manimal

OK here are my findings again.
Fuel module connected: oil pressure switch; key off(tan/white didnt have a gray) 0dcv, key on 9.36 dcv for 20sec, cranking 0dcv
Fuel module disconnected; oil pressure switch; key off 0dcv,key on 0dcv,cranking 0dcv
Engine running;fuel module connected; fuel pump test pig tail 12+dcv(actually 13.8dcv)

In you last test it is clear that relay is not energized.

Sanity check - did you check all your fuses on your main fuse panel (IFIK as I do not have FSM in front of me that there are couple of fuses related to EFI)???

Fuel module is providing back up power to fuel pump during POST. Once it is removed no 12V power reaches FP.

Conclusion BAD FP RELAY or FP socket since you have verified that 12 volts is supplied by ECM to the FP socket contacts between dark green/wht and black/wht wires during POST.

Measure relay coil resistance - it should be between 70 to 300 Ohms (depending on OE manufacturer) pins 85 and 86

Can you take a photo of your FP relay???

//RF

[kcblazer75]

I just thought of something that I haven't seen much mention of (if any) on this thread.

If you are installing TBI with the idea that your truck should keep running at high angles, you should consider making sure that your system will shut off in a roll-over.

With a fuel surge tank system installed, like an am doing, there is every possibility that there will be enough fuel in the surge tank to keep it running upside down!

My solution is to install a mercury switch that cuts power to the TBI system if I reach an angle of more than 90 degrees. My TBI ignition system is powered by a single HD relay, so I will just put it between the ignition source and the relay.

I'll have to experiment to make sure that a hard bump or bounce doesn't cause the TBI to turn off.

available from Parts Express - http://www.parts-express.com/pe/show...number=060-275

Lets hear it if you have other ideas.

Keith

[68 TT]

Originally Posted by kcblazer75

I just thought of something that I haven't seen much mention of (if any) on this thread.

If you are installing TBI with the idea that your truck should keep running at high angles, you should consider making sure that your system will shut off in a roll-over.

With a fuel surge tank system installed, like an am doing, there is every possibility that there will be enough fuel in the surge tank to keep it running upside down!

My solution is to install a mercury switch that cuts power to the TBI system if I reach an angle of more than 90 degrees. My TBI ignition system is powered by a single HD relay, so I will just put it between the ignition source and the relay.

I'll have to experiment to make sure that a hard bump or bounce doesn't cause the TBI to turn off.

available from Parts Express - http://www.parts-express.com/pe/show...number=060-275

Lets hear it if you have other ideas.

Keith

Something connected through a low oil pressure sensor (like the Auto Meter warning lights use) would do the trick. No worries about an impact setting it off. If you are on your side or upside down you don't have oil pressure for long.

http://www.summitracing.com/parts/ATM-3241/

http://www.summitracing.com/parts/REB-140-1345/

http://www.summitracing.com/parts/SMP-PS171/

Plenty of different pressure ranges out there to suit your specific engine.

It just needs to be low enough that your cranking oil pressure will turn it off so the truck will start.

[68 TT]

Originally Posted by kcblazer75

I'll have to experiment to make sure that a hard bump or bounce doesn't cause the TBI to turn off.

available from Parts Express - http://www.parts-express.com/pe/show...number=060-275

Lets hear it if you have other ideas.

Keith

One of the comments on that product is that vibration can set it off. Not good for a truck. A pot hole could shut you down.

Another is that they sometimes stick and need a tap to make them work. That would be bad if you were needing it to work to cut off the fuel flow.

[kcblazer75]

Originally Posted by 68 TT

Something connected through a low oil pressure sensor (like the Auto Meter warning lights use) would do the trick. No worries about an impact setting it off. If you are on your side or upside down you don't have oil pressure for long.

http://www.summitracing.com/parts/ATM-3241/

http://www.summitracing.com/parts/REB-140-1345/

http://www.summitracing.com/parts/SMP-PS171/

Plenty of different pressure ranges out there to suit your specific engine.

It just needs to be low enough that your cranking oil pressure will turn it off so the truck will start.

Sorry for the late reply.

That is a great idea. I like it better. A pressure switch is also a great safety in case you lose an oil pump, or lose your oil for some reason (bust the pan on a rock for example). That could save an engine.

Question... This would mean that turning on the ignition would NOT power up the ECM. So ECM would go strait from OFF to start when I crank the motor since there's no pressure until the motor starts cranking. Does the ECM require any "boot up" time to set things up before being ready to start? I know I wouldn't get that 2 second fuel pump hit at ignition on.

Is there any circuit that is ONLY hot when the engine is running, and not with just ignition on? I cant think of one. If I can find one, I could use that to allow power to the ECM when ignition is on, but not started.

Thanks

Keith

[68 TT]

Originally Posted by kcblazer75

Sorry for the late reply.

That is a great idea. I like it better. A pressure switch is also a great safety in case you lose an oil pump, or lose your oil for some reason (bust the pan on a rock for example). That could save an engine.

Question... This would mean that turning on the ignition would NOT power up the ECM. So ECM would go strait from OFF to start when I crank the motor since there's no pressure until the motor starts cranking. Does the ECM require any "boot up" time to set things up before being ready to start? I know I wouldn't get that 2 second fuel pump hit at ignition on.

Is there any circuit that is ONLY hot when the engine is running, and not with just ignition on? I cant think of one. If I can find one, I could use that to allow power to the ECM when ignition is on, but not started.

Thanks

Keith

I would only have it shut off the fuel pump relay and not the ECM main power so it wouldn't have to relearn every time you shut the engine off and it would be able to store codes until you wanted to clear them.

You would want it to only shut off the fuel pump relay after the engine started so the ECM pump 2-second prime feature works still and you could trouble shoot the system like normal.

Maybe if you wired the ground for the oil pressure warning sensor through the park / neutral switch so it only functioned when the vehicle was in gear. This way the fuel pump could be controlled properly by the ECM until you put the truck in gear then the low oil pressure sensor controlled relay could shut the fuel pump off if the oil pressure was too low. This assumes if you are upside down or on your side that the truck was in gear to get you there.

[cheepin]

So I still haven't been able to get my rig to start on it's own.I can put a little gas in the TBI and it fires right up then the injectors fire and it will run all day.But once you shut it down and let it sit it won't fire without putting gas in the TBI again.

Do I need to have the fuel pump hook up to the relay?I have it wired to it's own switch and relay.That is separate from the ECM.

[rfmaster]

Originally Posted by cheepin

So I still haven't been able to get my rig to start on it's own.I can put a little gas in the TBI and it fires right up then the injectors fire and it will run all day.But once you shut it down and let it sit it won't fire without putting gas in the TBI again.

Do I need to have the fuel pump hook up to the relay?I have it wired to it's own switch and relay.That is separate from the ECM.

Hey Cheepin

Lets solve your problem.

What you are describing is a classic Fuel Pump Relay or FP relay control circuit failure - malfunction. Oil pressure switch contacts close once oil pressure builds above 4-6PSI and that powers-up FP and engine is supplied with fuel and all is good.

1) Did you verify that your FP come-up during POST for 2 seconds??? It should if FP relay is functioning. Couple of electrical checks you must perform:

a) FP operates for about 2 seconds during POST. A POST is power on self test performed by ECM when IGN key is moved into run position. SES light goes from solid on - blinks off - back to solid on if all is good. ECM also power up fuel pump for about 2 to 3 seconds.

b) ECM supplies +12 Volts to the FP relay socket on dark green wire (ECM pin A1)

c) The black/white wire from FP socket is connected to a good ground.

If you can go through above check list you'll most likely find the culprit.
Let us know.

//RF

[cheepin]

I just got it figured out.I had the A-6 pin going to what I thought was a switched 12v source.Well it wasn't.I rewired it to a good 12v source and it fires up.Thanks for all your help.I may have more questions later.You never know.Again thanks.This thread is awesome!!

[kcblazer75]

Originally Posted by 68 TT

I would only have it shut off the fuel pump relay and not the ECM main power so it wouldn't have to relearn every time you shut the engine off and it would be able to store codes until you wanted to clear them.

You would want it to only shut off the fuel pump relay after the engine started so the ECM pump 2-second prime feature works still and you could trouble shoot the system like normal.

Maybe if you wired the ground for the oil pressure warning sensor through the park / neutral switch so it only functioned when the vehicle was in gear. This way the fuel pump could be controlled properly by the ECM until you put the truck in gear then the low oil pressure sensor controlled relay could shut the fuel pump off if the oil pressure was too low. This assumes if you are upside down or on your side that the truck was in gear to get you there.

Using the park neural switch is a great idea. I hadn't thought of that. I can make that work.

Thanks for the help!

Keith

[Patriot]

Originally Posted by bigblazerboy

i will be watchin this

Same here.

[kcblazer75]

here is the updated diagram and pic of my surge tank.

Keith

[rfmaster]

Originally Posted by kcblazer75

here is the updated diagram and pic of my surge tank.

Keith

Keith

Very nice - it should work. My only concern is to protect fuel system components from damage - rocks, etc. BTW where did you source that tank - is it home brew??

//RF

[kcblazer75]

Originally Posted by rfmaster

Keith

Very nice - it should work. My only concern is to protect fuel system components from damage - rocks, etc. BTW where did you source that tank - is it home brew??

//RF

That's all right above my drive shaft tucked into the corner of the frame and bed. I don't think a rock big enough to cause any damage would be able to get up there.

I got really lucky with the tank. I found it on my dads property. It is a high pressure tank from a very old refrigerator. I only had to add one port. I cleaned it out and pressure tested it for two weeks at 90 psi before deciding to use it.

Thanks again

Keith

[kcblazer75]

Rollover/low oil pressure cut off

Here is a diagram of the circuit I am considering adding to my truck.

The idea is to interrupt the ground to the fuel pump relay, effectively turning off the relay and the fuel pumps in the event of an abnormal loss of oil pressure. i.e. rollover or loss of oil.

When in park or neutral, relay 2 provides ground. This is for starting and the 2 second FP burst at POST.

When in drive, relay 1 provides ground. If there is a loss of oil pressure while in drive, ground is disconnected, and the fuel pumps turn off.

The only concern I have is that I could not find the specs for the oil pressure switch I have. ( it is three wire, shaped like a roll of quarters ). Im worried it might shut the fuel pumps off at low idle.

Feedback?

Thanks

Keith

Picture removed 9/5.

[RandyP]

Not a TBI swap, but a TBI replace, need some guidance so thought I'd make a quick post for the gurus.

First, making sure this is the wire we undo to time it with. We have the replacement motor all hooked up, new Holley TBI, edelbrock TBI intake, all new sensors... it's all new. Runs good, then runs bad, runs good, then runs bad. I now know we did not time it correctly, since we did not undo any wire, so need to be certain this is it for an 87 R10, came factory with a 350TBI. The wire I'm seeing is a tan wire with a black stripe on it, just comes out of a loom, and goes back in, to the drivers side fender of the brake booster.

And second, I'm really hoping I do not have to chip it or send it out for a tune, but I'm sure there is a strong chance of it. We replaced the engine with a GM 12499529 crate motor.
Horsepower: 290 @ 5100 RPM
Torque: 326 ft/lbs @ 3750 RPM
Max Rec. RPM: 5100 RPM
Compression Ratio: 8.5:1
Heads: Cast Iron 76 cc Chamber - 1.94 Intake valve/1.5 Exhaust valve
Camshaft Lift: .450 Intake /.460 Exhaust
Flat Tappet Duration @ .050" (222°Int/222° Exh)
Lifters: Flat Tappet
Connecting Rods: Powdered Metal
Block: 4-bolt main
Pistons & Pins: Aluminum
Crankshaft: Cast Iron Nodular, 3.480" Stroke
Rocker Arm: 1.5
Ignition Timing: 34° BTDC total advance

Edelbrock 3704 TBI Intake Manifold
Holley 502-6 Throttle body

Just in case anything matters, which I know it will.

[rfmaster]

Originally Posted by RandyP

Not a TBI swap, but a TBI replace, need some guidance so thought I'd make a quick post for the gurus.

First, making sure this is the wire we undo to time it with. We have the replacement motor all hooked up, new Holley TBI, edelbrock TBI intake, all new sensors... it's all new. Runs good, then runs bad, runs good, then runs bad. I now know we did not time it correctly, since we did not undo any wire, so need to be certain this is it for an 87 R10, came factory with a 350TBI. The wire I'm seeing is a tan wire with a black stripe on it, just comes out of a loom, and goes back in, to the drivers side fender of the brake booster.

And second, I'm really hoping I do not have to chip it or send it out for a tune, but I'm sure there is a strong chance of it. We replaced the engine with a GM 12499529 crate motor.
Horsepower: 290 @ 5100 RPM
Torque: 326 ft/lbs @ 3750 RPM
Max Rec. RPM: 5100 RPM
Compression Ratio: 8.5:1
Heads: Cast Iron 76 cc Chamber - 1.94 Intake valve/1.5 Exhaust valve
Camshaft Lift: .450 Intake /.460 Exhaust
Flat Tappet Duration @ .050" (222°Int/222° Exh)
Lifters: Flat Tappet
Connecting Rods: Powdered Metal
Block: 4-bolt main
Pistons & Pins: Aluminum
Crankshaft: Cast Iron Nodular, 3.480" Stroke
Rocker Arm: 1.5
Ignition Timing: 34° BTDC total advance

Edelbrock 3704 TBI Intake Manifold
Holley 502-6 Throttle body

Just in case anything matters, which I know it will.

Good Morning Randy and welcome to the thread.

1) The single pin connector is used to set base timing (EST bypassed). For stock C/K trucks it is 0 deg, F bodies with TBI it is 6 deg. There is a detailed step by step procedure how to set base timing.

2) The 290HP crate motor is a poor choice for a stock TBI system (or Holley equipped for that matter). The problem lies with cam that GM chose for that crate engine having 222/222 deg (0.050) duration. It is nice rumbling cam for carb equipped rod, but it is poor choice for a truck. The rest of the engine is great, but this cam used on the 68-81 L-46 and L-82 Corvettes does not create enough vacuum at idle for stock ECM calibration. You can try mail order chips (tbichips.com) service or swap in 'TBI friendly' camshaft better suited for truck duty.

//RF

[rfmaster]

Originally Posted by kcblazer75

Rollover/low oil pressure cut off

Here is a diagram of the circuit I am considering adding to my truck.

The idea is to interrupt the ground to the fuel pump relay, effectively turning off the relay and the fuel pumps in the event of an abnormal loss of oil pressure. i.e. rollover or loss of oil.

When in park or neutral, relay 2 provides ground. This is for starting and the 2 second FP burst at POST.

When in drive, relay 1 provides ground. If there is a loss of oil pressure while in drive, ground is disconnected, and the fuel pumps turn off.

The only concern I have is that I could not find the specs for the oil pressure switch I have. ( it is three wire, shaped like a roll of quarters ). Im worried it might shut the fuel pumps off at low idle.

Feedback?

Thanks

Keith

Keith

Try to locate GM part number stamped on metal portion of the sensor body. Take a trip to a Chevy Dealer parts counter and see what his parts books have to say. From what I know - 4 to 6 PSI is a range, but there are exceptions as well.

//RF

[Chad77]

Ok 1st of all This thread I have learn quite a bit a big thank you to all!

Just to let ya's know I have read this from pg1 to pg23 whew alot of going on.

OK now on to the Q's .

1. Their is a link to a fuse block If if remember wright anyways the link is dead!

2.Ok I have the original ALDL plug out of the 88 pickup do I just route the wires required for this wright into this plug or is there something to go between IE fuses .

3. Even thoe I read through this front to back and followed the printout where do I hook the Injector power up along with the other power ?

4. I have the single (BIG) relay for the fuel and their is a pink/black wire that comes out of that and goes to a plug their is also a Orange wire and they are both connected to a plug I think this is the oil press plug am I wright.... Bottom look lets see g/w to com p/b to fuse and (plug no clue) b/w ground tie org to tie, What do I do with the red/white?

Here is a reference pic
I was wondering if I could put the senor in the location in the red square?
I have read many different things on the injectors and now confused can some one tell me witch ones these are?


Sorry for the size no clue on how to make them smaller.
thanks for any info.....

[rfmaster]

Originally Posted by Chad77

Ok 1st of all This thread I have learn quite a bit a big thank you to all!

Just to let ya's know I have read this from pg1 to pg23 whew alot of going on.

OK now on to the Q's .

1. Their is a link to a fuse block If if remember wright anyways the link is dead!

2.Ok I have the original ALDL plug out of the 88 pickup do I just route the wires required for this wright into this plug or is there something to go between IE fuses .

3. Even thoe I read through this front to back and followed the printout where do I hook the Injector power up along with the other power ?

4. I have the single (BIG) relay for the fuel and their is a pink/black wire that comes out of that and goes to a plug their is also a Orange wire and they are both connected to a plug I think this is the oil press plug am I wright....

5. Their is one more Q but I need to take a pic so everyone knows what Iam talking about...

thanks for any info.....

Welcome to the thread Chad

1) Few questions first - what are you working on, model, year, etc? Second, what is the year of TBI system that you are using? 88??? Regarding fuse link - you may want to take a snapshot of it and posted. There are several and things changed over the years. So the key to this is to identify what it is, how it works and is it really needed.

2)ALDL connector needs a handful of wires routed to ECM and ground:

Pin A Ground (black/white or black) - make sure that it ties to ground and ECM A12
Pin B Diagnostic (white/black) )
Pin C can be omitted
Pin D SES - (brown/white) very handy if your panel SES light is not working
Pin E Serial data (orange)

3) Injectors need +12V power from IGN circuit - fuse box. The key is to find circuit that is hot when ignition is in RUN and CRANK. I use a BOSCH relay powered by IGN (purple wire that powers ignition coil) to provide separate circuit for injectors. You'll need 10 AMP fuse for circuit protection. ECM has two power circuits. Battery on B1 - use 10 AMP circuit and run to battery (always hot) circuit and the other is IGN On - Pin A6 (pink/black) also use 10 AMP inline fuse for circuit protection. You'll have to find circuit in your fuse box that is hot with ignition on and during cranking!

4) You are describing Fuel Pump relay (FP)
FP relay socket should have orange wire - that goes to battery via fuse link, Gray wire - that wire provides switched power to FP in the gas tank (or inline). Pink Black wire on FP socket is used to prime or test fuel pump. The oil pressure switch usually has three wires: orange, gray and brown. Orange goes to battery, gray goes to FP and brown is used for dash light or gauge. FP socket should have two more wires: dark green and black-white. These are used by ECM to power FP relay.

5) Sure - take pictures. It makes everything easier.

//RF