retrodude

I'm having a terrible time nailing down this issue and I know collectively all the geniuses here have some good ideas.
Backstory: two years ago ignition just shut off while driving. It only did it three times that year. I replaced multiple parts hoping that fixed it.
That following year I didn't have any ignition issues.
This year they started up every time I go out.
Symptoms: after driving 10 to 15 miles ignition just shuts off like you've turned the key off. I pull over and wait 5 to 10 minutes and it will restart.
I can drive a little ways further and it will quit again. When trying to restart it it has a real funky exhaust smell. It's stumbles and sputters and then finally starts up.
What's been replaced: ignition switch, horn relay, alternator, MSD box, coil, distributor. I've added an additional single point of grounding under the hood where I've grounded the engine to the frame the frame back to the battery. I wrapped all my fuel line in shielding to rule out vapor lock. I have an electric pump and every time it quits I checked and I have fuel pressure at the carburetor and the carburetor will squirt gas.
I feel I replaced every possible ignition part...is there something else I'm missing or just not thinking about? Thanks, Allen

Big2Bird

What year?
What distributor?

GTOguy

Without a year and type of dizzy, it's impossible to give any valid advice.

Les

I'd carry a spare spark plug in the car and drive until it shuts down. Then I'd pull the easiest to reach spark plug boot off, put the spare plug into it, ground the plug to a safe spot, and have somebody turn the engine over while watching for spark at the plug. If it has spark, you have a fuel delivery issue. If not, you'll need to keep digging for the ignition issue- which is always fun. Good luck.

Tampa Jerry

A quick way to determine if it's fuel related issue is to carry a can of carb cleaner with you. When the car stalls, spray some carb cleaner in the carb. If it starts and dies, you have a fuel problem. Check your fuel filter, sock in the tank, bad rubber fuel line etc. On the ignition side, sounds like it could be heat related. Carry a can of dust off with you and when the car stalls, spray down your electrical components to cool them down. If the car starts up, you get the idea. Jerry

retrodude

Thanks for the replies...
It is a 69 BB ZZ454. I had an MSD distributor with a 6AL digital ignition and MSD Blaster SS coil. I pulled it out and sent it to MSD to check it out. I put in an HEI distributor now and it didn't help. I even took the hood off to check for heat issues. When it stalls and tries to restart, you can hear it stumbling and missing. The carb has a pressure guage from an electric holly pump that I can hear running.

Big2Bird

Did you use the old battery connection, or run a keyed 12 v to the dizzy/msd?

jnb5101

It sounds like you're boiling the gas. The fuel gauge may show pressure, but it might just be vapors. Do you have a well positioned (very close to the carb) fuel return line?

kanvasman

Second vote for the boiling gas. You have a lot of engine in a small space and in my corvette history ( especially with aluminum manifolds) the heat goes to the carb. We used to have insulators ( spacers) that fit between the carb and the manifold that kept the heat transfer down a bit.

3X2

First thing I learned when dealing with Corvette electrical issues: check, clean, and tighten all grounds in the circuit. I add a dab of dielectric grease to any connections exposed to the elements.

Jud Chapin

I had a '69 Grand Prix that did the exact same thing. It was the sock in the fuel tank.

Big2Bird

I have seen this 3 times in 5 years on the older cars. They just collapse/clog/ and cause that very symptom.
If your LUCKY, it does not clog the fuel line, or get stuck in the pump check valves.

Jud Chapin

In my case the sock would just bend from the pump suction at the mesh connector. Once it sat for a few minutes after the problem showed up, it would straighten out and be ok. Drove me nuts until someone told me to check it.

694speed350

on another brand of car I had the same problem It was a fuel feed problem. Old gas.

mysixtynine

The chances of two completely different distributors and ignition modules (HEI / 6al) having the same issue is very unlikely. A timing gun is a simple way to test for ignition pulses without taking anything apart.

That leaves the source of the 12v to the distributor / module. Check the voltage at the distributor when this is occurring. What wire/source are you using to power the new distributor?

It also brings to question your carb / fuel. You state you have fuel pressure at the carb when this is occurring which should rule out vapor lock. Keep in mind what vapor lock is and where it occurs.... It happens at the auction side of the pump and essentially the pump cannot pull liquid fuel from the tank so you should have no pressure at the carb if it was vapor lock.

Boiling of the fuel in carb should manifest itself after the car is shut off not typically when it's running. The engine running pulling atomized fuel and air through the carb cools the carb while running. It's when the engine shuts off that boiling usually has its effect. The boil over would cause the fuel to percolate out of the carb and down into the intake saturating the intake track and cylinders effectively flooding the engine making it very hard to restart after a 5-10 minute wait.

What type of carb? What pressure are you running ? What electric pump? Do you have a pressure regulator between the pump and the carb?

retrodude

Those are all good ideas, I looked at the sock, should it be totally round? Is it necessary if I have a filter down stream? I'm thinking I can cut it off for now to see if it fixes it.

retrodude

Thanks mysixtynine . It is a Holley red pump and a Holley 850 double pumper. I have 5-6 lbs of pressure right at the carb. I'll check the 12v going to the distributor. It just has 2 wires from the MSD box. The HEI I put in for a test part wasn't hooked to the MSD.

retrodude

Big2Bird

Oh yeah. It's dying. You may still have an ignition issue, but that sock is collapsing.

mysixtynine

Where is the pump located? Should be close to the tank as possible. Make sure the gauge is really working.

How are your fuel levels in the bowls when engine is hot?