So this weekend racing, ran into a problem. Car runs great until about 2 miles into the course. Then it falls on its face. Can barely keep it idling. If I let it sit for a couple minutes it will run fine, but soon fall back on its face; seems like a thermal issue.

Replaced opti
Replaced injectors
Replaced plugs

Only thing left I can think of is the coil. Not overheating, good oil pressure, still haven't checked fuel pressure but I'm pretty certain thats good too . . any thoughts appreciated!

 

I would try double checking the fuel pressure when you have the problem. When I had a fuel pump going out, it would usually run fine when I started it cold, but would have a problem when it warmed up. The conditions sound about like yours. Sometimes it would completely stall and would not restart until a cool down of 10 or 20 minutes.

 

Sorry, forgot to add that I also changed the fuel pump :/

 

Any other suggestions? Rather have some leads before throwing more parts at this thing :P

 

Sounds like a ICM

 

Get the fuel pressure gauge installed, grasshopper. I did and I was glad I did. I had similar symptoms on my '94 LT1. It seemed thermal to me too. But without the fuel pressure gauge, you cannot eliminate the fuel system.

I found that when the problem occurred, the fuel pressure dropped slowly to 0 over a 3-5 second period. After much diagnosis/wire chasing/etc, I found the fuel pump relay to be bad. Did the 'old A-B-A and when I pulled out the fp relay, it was hot to the touch.

MD

 

Yeah, I'm gonna do that. I don't think its fuel pump however. Reasoning:

We're actually not running the standard fuel pump. I'm running a fuel system from a boat (yeeehaw) because race car.


It has a low pressure lift pump going through a filter, feeding into about a quart of reserve (swirl pot) with a high pressure pump feeding to the engine. Both were brand new, I had two on hand. When I swapped it out mid race, no improvement. If it were a fueling issue, the only thing I could imagine is that either A.) The relay may be going bad (standard relay) or B.) I'm collapsing a rubber hose on the tank lift side. I'll still throw a pressure gauge on there to monitor that.

I'm really really leaning towards it being an ICM/Coil issue.

 

Most auto parts stores can test them. The best way is to do multiple tests to get it nice and hot, which simulates the real world. A single test just doesn't stress it enough to prove it's good/bad.

 

Might not seem likely, but pressure requires correct volume. Could filter be bad, even if fresh? At least as likely as a collapsing suction line. Just scratching my head with the rest of you. Or maybe a faulty line back to tank, causing too much vacuum in fuel tank?