rrubel

Looking for the next place to go with this issue. '86 4+3, highly modified engine, ran fine until fairly recently. Now it stalls sometimes while idling and then is very hard to restart (to where I had to pop-start it recently). This usually happens when the engine is warm -- sitting at a light or something, it's idling fine around 8-900 (recommended idle speed for this cam) and then it'll drop down to about 2-300 and die. Hitting the gas doesn't help. After this, it'll crank fine but wont' start -- although the last time it happened, I found that if I floored it while cranking it'd start right up. That SOUNDS like a fuel delivery problem, but the pump and relay are both new and my fuel pressure readings at idle are steady (though I have not been able to take a reading when it dies -- so far it hasn't done that when I've had the gauge hooked up). I also recently replaced the ignition module in the distributor based on another recommendation but that hasn't helped either.

Any other thoughts? The IAC is working, but I can't get counts because of an issue with my ALDL connector that I'm also trying to diagnose...

I do have a new fuel filter ready to put on when I have some free time.

Thanks
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GregMartin

Kevova

Codes? I would look at ignition system. Weak spark would lead to stalling, also flooded / overfuel on restart. Holding pedal to floor puts ECM in "Clear Flood" mode.

rrubel

Thanks for the responses so far.

No codes, no CEL. I had the same idea about the flooding and "clear flood" mode, but I'm not sure how to check for that, or what might cause it. Injector getting stuck open? The car runs fine when not idling; I'd expect a weak spark to cause it to die under load too, or at least miss a lot, and that doesn't happen.

The ECU is far from the stock program and is still in progress, but I've tried different versions of binaries that have worked fine in the past, so I strongly feel it's mechanical and not programmatic.

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Kevova

How often does it stall? Data log and watch fuel pressure , try to catch and irregularity when stall occurs. Ignition module or coil would be a guess. Poor connections.

rrubel

Just replaced the ignition module. How often does it stall? Seems like once every time I drive it... but no more than once, and no pattern I can discern regarding how long until it does stall. One day it was after 25 minutes of commuting stop-and-go -- stalled at the last light before my house. Another day, it was just after I bought gas (so a fresh restart) and had only driven a mile or so before that. Another time it was just after I pulled out of my driveway, at the first stop sign. Other days, doesn't happen at all -- though TBH I've cut way back on my driving it since this started happening. People in my area HATE missing a light due to a stalled vehicle and REALLY let you know this!
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Kevova

Grounds or loose connections.

VikingTrad3r

coolant temp sensor. sending wrong temp, flooding engine to stall. when you floor it, it sends clear signal and starts.