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Discussion Starter #1
Dont even know where to start with a search, tried heat soak and vapor lock, but not coming up with what I need.

LS1, running a walbro 255(I believe) and a corvette filter/regulator, oem gm carbed tank, 3/8" feed line, returnless rail, etc. Turn key engine harness, non feedback.

Has a random no start, only when warm. Time seems to be the only cure.
Injectors pulse, plugs spark, have fuel pressure.

Also developed a random rough idle/bogs under load, and once the pump was whining. Doesnt stall, but wont restart when it has issues.

Cant get a scanner on it without an adapter I guess, but it came to me tonight that the exhaust is pointed at the fuel tank. dual 2-1/2s, and literally directly at the point of the tank that the pickup is. The fuel pump doesnt appear to be getting hot when it happens, and it was refused to restart before with no apparent idle issues(no load, in park)

Could it be that its actually as simple as the exhaust needs the turndowns?
 

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You REALLY don't want to wire in a diag. port, do you? :)

I say replace everything. Its the only sure way to fix it while blindly taking stabs in the dark. :)

J. J.
 

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Discussion Starter #3
Pulling the wire down tonight to look at it. Apparently I just need an adapter and the port is allready there, but I'm wondering if its something so stupid simple that I looked past it after the exhaust guy was done with it(and forgot the turndowns)
 

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When it does it have you tried wiggling the ECM connectors? I've had that happen to mine in just the short period of time I've had it running when I didn't have the little security levers pushed all the way down. It allowed the contacts to just BARELY contact causing an intermittent no start that I could duplicate by wiggling the plug.

From what I've seen of the LS1 ECM's the plugs are even shittier than mine in terms of being able to secure themselves.

J. J.

Edit: Just went back, I did not have rough idle when it happened.
 

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Discussion Starter #5
Yup. Wiggle tested the entire harness when it happened both times. ECM is safe mounted to the inside of the firewall behind the glove box, everythings secure, unplugged it completely and plugged it back in to make sure last time.

It ONLY does it hot though, thats why all of the sudden Im leaning towards vapor lock.
 

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Discussion Starter #8
Same here, it seems to be a time thing to restart.

I've been playing that its an electrical thing for a while, but the exhaust got me wondering. It hasnt ever stalled that I know of, the most noticeble issue when running it literally sounded like it was starving for fuel, it had been pushed hard for about 15 minutes, maybe 20, running for about an hour, and the fuel pump started whining, it sounded like it was starving for fuel. If we had left it running all day Im fairly certain that it would have kept running all day.
 

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Really you made a post about this :laughing:


Do you know what vapour lock is? and how easy it is to get rid of in efi system cycle the key to move fuel or hard wire the pump to run new fuel though.

it's not a bloody carb with mechanical plunger :shaking:






Slow fuel pumps show upper rpm issue aka load just like a plugged filter




hint hint



cheak wireing and GPM (Gallons per minute, a unit of volumetric flow rate) and go form there




have fun :homer:
 

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Discussion Starter #10 (Edited)
If you want to talk mushhead, then drop by any time. Until then its not your knowledge I'm looking for.

Beyond the fact that if you had half a clue, you would realize that its a returnless system so you cant just cycle it.
 

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crack the line then so the vapour will escape

ps return less system's don't use fuel reg's they use voltage regs should be a bit more clearer next time


so your problem even got smaller


besides the controller being bad

and every thing behind that


have fun :homer:
 

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Discussion Starter #12
And everytime you open your mouth you show how little you actually know. Maybe you should tell all the guys running fuel filters with integrated regulators that they are hooked up wrong, and while you're at it, let GM know that you have it figured out as well. Shut your mouth when you dont know what you're talking about.
 

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you are still stuiped and I will know this form talking with you in person.

and trying to start a jeep for 1 hour finding out at the end it was out of gas

even a 2 year old will smell the tail pipe to see if smell like gas form flooding when diagnosing a issue with starting

or the piel of piss at one of the tough trucks that you built for it that could not make it 5 feet with out deing and stuff that you built for that event.

good luck he haw


i may not be the best at spelling but at lest i can fix motors and electronics and under stand how they work



reason being is your answering you own bloody question in your own post's
 

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Spidr has been very knowledgeable and helpful everytime I have been to his shop. I have an LS6 in my Jeep and it took abit and some good questions to get and keep it running. Pirate4x4 and the LS1tech have both been excellent sources.
 

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Discussion Starter #17
Its OK buddy. Hes just a troll, and hes either banned or run off from both the local boards. He holds it against me and so be it.

We'll get it figured;)
 

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I had starting issues due to a bad cam sensor. It is only used for starting and does not effect a running engine until you have to restart. Time would somehow help it start, don't know why. It also backfired but I was running a propane carb. EFI might not backfire due to the injectors. The cam sensor was in stock at NAPA for $40. Sensor is on the top of block at trans end.
 

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4X4 HACK
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Fuel related
What is your fuel pressure key on engine off and what is your pressure when no start. If you have a power probe or jumper wire you can apply voltage to the pump during no start too. Or you can measure the resistance through the pump and use Ohms law ... V/R=A most pumps 50-60psi are 4-7Amps @13V(+/-)

I dont know how to accuratly diagnose computer contolled cars with out a scanner, scope, DVOM, alldata, and identifix .. good luck
 
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