Need help to get truck started

[Lobo'74]

Truck turns over but won't start. Usually when it does this the starter module in the HEI is bad. Took it out and over to Advance Auto. Sure enough, its bad. Replaced it with a new AC/Delco ignition module. Still won't start. It ocassionally catches and runs very rough for about 15 seconds, then quits again.

Since the ignition module burns out about 3 times a year I thought the problem had to be with voltage in or a bad ground. Voltage in is from a switched spade on the fuse block that goes to the HEI only. Pulls the same as the electrical system puts out, 12+VDC. The ground checks out fine. The entire metal body of the distributor shows a good ground. The center sapde on the edge of the coil (C- GND B+) shows a good ground.

I am clueless as to why this 1979 350 in my '67 eats the ignition modules, and am clueless as to why it won't start now.

I sure could use some good ideas here . . .

[dwaite72lnghrn]

Check the voltage with a meter with the ignition switch "ON" and engine not running. It should be about 12.5-12-9 with a good charged battery. Then you need to start the truck and check the voltage with the engine running and it should be about 13.3-13.8 with a charged battery. If you are blowing them that fast it sounds like you are running to high a voltage (bad regulator). I know this doesn't help you now but when we get it started you need to make these checks.
Can you get someone to crank it while you check the voltage to make sure you have voltage during cranking?
Also check the cap for any cracks or carbon traces between the connections.

[cdowns]

take the ground wires between frame and engine and battery APART AND CLEAN THEM just because a meter shows a ground(millevolts and milleamps) doesn't mean you've got a good ground

[Lobo'74]

OK. Not running the volts are right around 13. Like 12.5-13.5VDC. From my volt meter on the dash its about the same when running. Its a little more, like 13.5-14.0VDC when running.

Inside of the dist. cap looks good, the wear pattern on the inside of the cap shows timing is good too.

I'll check the grounding strap too. I was using an OHM meter to check it - goes to zero ohms checking ground at the metal of the distributor body. I'll clean up the strap too.

Any other ideas?

[rkarr]

I wonder if maybe one of the diodes are blown in the alternator....
I've never heard such a high failure rate...
I'll be watching this thread for sure..
be sure to let us know when you do get it figured out...

[VetteVet]

Are you still running the external voltage regulator? I read somewhere that they were known to cause ignition modules to burn out. I do not remember the reason and I can't find the article. I just remember reading it. If I find it I'll post it.

[Lobo'74]

Nope, its an internal voltage regulator - part of the alternator.

[GMC Jim]

when mounting the ignition module, heat sink compound MUST be used between the unit and mounting surface. Without the compound, premature failure will occur. Coumpound can be secured at GM parts dealers.

[Lobo'74]

I use a thick layer of the heat sink compound every time I change the module. Additionally, I clean off both surfaces before I install the new module with the compound on it.

I think I've got all the bases covered and am following all instructions to the letter. Thats what makes this so frustrating.

[Lobo'74]

I am going out with my multi meter to check:

*the primary coil resistance on the "TACH" and "BAT" terminals
*the coil resistance between the carbon button and the "GND" and "Bat" terminals
*the pick-up coil
*taking the new module back to Advance to test it and see that it is still good. Can't see how it would burn out in a day though . . .

[ChevLoRay]

Originally Posted by GMC Jim

when mounting the ignition module, heat sink compound MUST be used between the unit and mounting surface. Without the compound, premature failure will occur. Coumpound can be secured at GM parts dealers.

This is a MUST!

The modules that I have bought at NAPA, always came with the dielectric compound. NAPA also sells it in a box of 10 packages, each sufficient for one module install. But, it ain't necessarily cheaper that way.

I've mentioned this a few times in the past, but I had a problem with my old HEI, in which the wire to the reluctor would move when letting off of the gas. Doing that, caused the vacuum to increase, and that changed the advance setting in the distributor. When it did, it would move just enough to break the connection going to the module, and the engine would die.....just like turning off the key.

I gave up on that HEI and bought an ACCEL reman HEI, and installed it. I highly recommend that route, if you continue to have problems. Your '79 model HEI has internal wiring that is 27 years old, assuming it has never been rebuilt. It's just a suggestion, but you seem to have narrowed the problem to the distributor and the voltage you cite is not out of line.

[Lobo'74]

Actually, entire engine was rebuilt about 3 years ago. I bought it from an engineer in his late 40's who has been rebuilding engines and building hot rods since his high school days. LONG list of mods, but basically, sportsman II heads, flat top high silicon content pistons, cam, edelbrock performer rpm manifold, edelbrock #1407 750cfm carb, headers. The HEI was a new one when I bought the truck two years ago.

Just finished trouble shooting the system with the following results:
Test......................as measured................optimum...................results
Volts @ battery.........12.75 VDC ..................12-14 ?....................good
volts @ distrib. pwr in....12.5 VDC..................>12.......................good
Ignition Coil-
-----Primary Resistance...0 ohms ..................0 ohms.....................good
-----Carbon button-GRD...14.9 ohms.........not infinite resist.............good
-----Carbon button-BAT.....inf. ohms.........no measured ohms...........good
Pick-Up coil---
-----White - GRD........infinite ohms.............infinite ohms...............good
-----Green - GRD........infinite ohms.............infinite ohms..............good
-----Green - White......750-800 ohms...........500 - 1500 ohms..........good
Ignition Module..........pass on tester...........pass on tester..............good

Everything tested out to spec. The only thing I found that was not good was the wiring harness at the distributor. The one that goes from the internal capacitor then to the ignition module on one end, and to the coil assy “C- GRD B+” terminals on the cap on the other end. The harness was cracked all the way through the insulation on all three wires at both ends. Can’t get a new one at the parts store, they say its a dealer item.

I will get that on Monday after Easter and install it. Hope that fixes it. Other than the cracked dizzy harness everything else checks to specs. . .

Its a puzzlement.

[beaterC10]

A good parts store should have the dizzy harness, somebody like NAPA or Car Quest.

You might look at the coil, I had the same issues you are having. When I replaced the coil and the module with decent parts the issue went away. I noticed a lot of the cheaper ignition parts are made overseas and don't last long. I would assume that the Delco parts are good.

[Lobo'74]

Got the new AC/Delco "terminal block assembly" Thats the dizzy harness from the capacitor and ignition module on the dizzy end to the coil assy terminals on the cap. Mine had the old can shaped capicator, the new one had a small square block as a capacitor. Since everything else checked out normal electrically I put it all back together (with a new coat of dielectric grease from GM) and tried to start it.

It turned over right away but was running rather rough. No surprise since it sat since late Dec/early Jan. Gave it a couple of pumps on the gas and it reved but sounded like a huge header leak ("chuffing" noise) and started winding down. Like it had no power. Pumping the gas gave no response and it died. Can't get it started again.

Started pulling plugs to see their condition. They are all black, like a rich mixture or burning some oil, and all the ones I pulled (I quit at 3, 1 left side, 2 right) were wet with gas.

Its like its just not getting spark. The next thing I can think of is the coil, but it showed the correct readings on the test earlier (see specs in 4/15 post).

I hate to have it towed to the shop but I'm out of ideas.

Any more help on ideas I've missed?

[jhow66]

You got carb problem-flooding-wet plugs no start. Take all plugs out and clean them. Take gas line off fuel pump (tank side) and plug it so as not to lose gas. Before putting plugs back crank engine over to blow any gas in holes out. Install plugs and restart engine. If your carb is flooding it should run ok until carb runs out of gas. Hook fuel line back up to fuel pump. Restart. If it dies again fix your carb problem. (dirt under needle, sinking float, or you are gas fouling your plugs trying to start it when your ing. goes out.)

[Lobo'74]

Thanks. Going out to do all that right now. (early AM 4-19)

[Chevrolet4x4s]

If thats not it look at the center of the distributor cap and see if the peg comming down from the coil is still there.I had one to burn off way up into the cap not the 1/4''(est) down that it should be.
Hope this helps
Shane

[Jerry Jones]

Originally Posted by jhow66

You got carb problem-flooding-wet plugs no start. Take all plugs out and clean them. Take gas line off fuel pump (tank side) and plug it so as not to lose gas. Before putting plugs back crank engine over to blow any gas in holes out. Install plugs and restart engine. If your carb is flooding it should run ok until carb runs out of gas. Hook fuel line back up to fuel pump. Restart. If it dies again fix your carb problem. (dirt under needle, sinking float, or you are gas fouling your plugs trying to start it when your ing. goes out.)

If it is flooding, try taking a screwdriver handle or wooden hammer handle and give the body of the carb at the fuel inlet a few "moderate" taps. Sometimes when they sit, and/or bad gas, dirt gets between the needle and seat. If the tapping doesn't free it up, then you may need to pop the top off of the carb and clean it out.

[Lobo'74]

I took the fuel filter off about a week ago. Rather than pour the gas on my asphault driveway I poured it into the carb thinking it would evaporate and/or get used up. Had a bad ignition module then, went through all the above to fix the module and "terminal block" wiring. Did I screw up when I poured that 1/4 cup of gas into the carb? (right down the small venturi's) . . .

[Chevrolet4x4s]

Its just flooded really really really bad from all of that gas.
Shane

[70rs/ss]

It is flooded from all your craking and pumping, remember when you tried and tried to get it started? My guess is that you wiring (part you changed) was the cause of the module failure, you replaced the module and still had the wiring problem, changed the wire, and it started, but with all the trying and no spark, you flooded the crap out of it. New plugs and it will start and run fine. I'd think?!

[Lobo'74]

YeeeHaaa!

Got it started!

I did as was suggested - pulled off the fuel supply line from the fuel pump, pulled all the spark plugs and turned the engine over (twice) for 10 or 15 seconds. While I was at it I replaced the disposable aluminum canister style fuel filter with a glass in line fuel filter with replaceable filter elements . . .

I then put in new AC/Delco R44TS plugs and reinstalled the fuel supply. It started on the first try. Ran a little rough initially, but I smoothly reved it to 3000 and it smoothed right out. Let it warm up at a fast idle while I cleared an open spot to get it out of the driveway and took it out for a spin. Runs great.

The front plug on each bank of the engine has the 90 degree boot hitting the header, so I'll have to get two Accel 576S "shorty" plugs for those two cylinders. Also, I suspect the ignition modules may be having trouble above 5000 rpm. The engine was balanced as part of the high performance rebuild and I've been given red line figures of 6500 to 7000 rpm. That seems pretty high, so I use a 6000 rpm red line. Since its a stock HEI I think it may toast itself above 5000. If it does it again I'll go with a PerTronix Flame Thrower Street/Strip HEI distributor set up.

Thanks to all for all the help. Feels good to be back on the road.

[LONGHAIR]

It has been said before, but is worthy of repeating...........get rid of the glass filter. It is a potential fire hazzard. Yes, it is Pyrex (or some other tempered tuff stuff) but it is still glass. There have been members here reporting fires from these.

[70 shorty]

I remember that truck from the Pocahontas get together last summer. I didn't realize you had all the hot rod parts on that small block, but it was a nice looking truck. Good to hear you got it going again. I had a similar problem with the old shorty rust bucket, with a carb that the truck didnt' want to run. I put a spare 600 Holley I had lying around on the on inline 6 and it runs fine, but needless to say, gas mileage is non existant.

[Lobo'74]

Hmmmm... 4 barrel on a 250. That might give worse mileage than my first car - a '66 Impala with a 396 and a powerglide tranny.

Another run this summer would be fun but gas prices are putting a wet blanket on the idea.

Tomorrow in addition to the 2 shorty spark plugs I'll also be looking for an edelbrock 8837 in line ALUMINUM fuel filter. Thanks for the heads up on the problems with the glass.

Always get good ideas from the board members.