LT1 issues
Thread Starter
Race Director
Joined: Feb 2008
Posts: 19,691
Likes: 322
From: Alexandria VA
LT1 issues
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!
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!
Le Mans Master
Joined: Jun 2009
Posts: 6,528
Likes: 752
From: South Dakota
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.
Thread Starter
Race Director
Joined: Feb 2008
Posts: 19,691
Likes: 322
From: Alexandria VA
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.
Advanced
Joined: Apr 2011
Posts: 58
Likes: 4
From: Fenton MI
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
Thread Starter
Race Director
Joined: Feb 2008
Posts: 19,691
Likes: 322
From: Alexandria VA
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
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
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.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
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Racer
Joined: Mar 2014
Posts: 253
Likes: 119
From: North Branch Michigan
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?