don't let the subject title fool you, this isn't really a engine swap question per-say.

But, yeah, i put an LT-1 in the car, and i bought a BRAND NEW fuel pump with the 95 corvette LT-1 part number from autozone, and according to the specs, it's supposed to push 80-90 psi!!

i finally got the motor to where it would crank, and it fires and dies after about 2 seconds..

VROOM glug glug glug glug glug dead..

immediately, i thought it was a fuel pressure issue so borrowed a fuel pressure gauge from the shop next door.

The standing pressure is 40psi...

the PRIME pressure is about 45psi

when i start the motor, it drops and stays at 35-37psi until the motor dies, and it re-primes and pushes the pressure back up to 45 until it stops priming and settles at 40 again when the priming stops.

soooooooooooooooo wth?

again, BRAND NEW lt-1 corvette pump

http://www.autozone.com/autozone/par...vice=273186155

(((if the link works)))

stock 91 RS fuel lines....

do i need to upgrade the fuel lines from the TBI fuel lines to TPI fuel lines????? god i hope not! I was under the impression they were one in the same and would easily handle the pressure, but, i think it possible that not enough pressure can build, if the lines are too small under the car.

just a thought....

any other thoughts???????

i have also considered the fuel filter, which has not been replaced, and could probably stand to be, but i'm not sure if it would kill HALF of the pressure from the pump.

i'm trying not to just through nickle and dime parts at this to fix the issue.

"oh maybe this $20 part, or maybe this $50 part or maybe this $100 part" until it works. i'd rather have a solid diagnosis if possible.

Thanks!!!!

 

potential self diagnosis... please share thoughts and opinions.

1. vaccuum! i haven't gotten the vaccuum system in tact yet.. so, though the fuel rail is hooked to the intake, i'm not sure if it is actually sucking well enough to actuate the vaccuum "dealy" on the back of the fuel rails, and may be letting too much fuel out to build pressure.

2. i had the injectors and rail ultrasonic cleaned, so there may still be water in said diaphragm, and if there is pressure on both sides of it, it won't "phragm" haha

3. pressure regulator input voltage????

4. is there a fuel pressure SENSOR somewhere? i wasn't the one who wired it, and i'm not sure what sensors are there or not there for it..

so that's 4 ideas i have, let me know if any or all of this is true please, as well as anything else i may be missing!!!

 

This may be a dumb question, but have you replaced the regulator or put an adjustable one on it?

 

45 psi with the pump on but engine off is normal. So is 35 psi at idle. Why do you think it should have more? I think you have an issue somewhere else. I'm not sure where to look first but that kind of pressure sounds normal toome.

 

Prbably loosing spark or inj. pulse.

 

Start checking other systems

http://www.mainstreamtopics.com/foru...rt-diagnostic/

 

stock regulator on it... as for the fuel pressure, i'm not sure what i was thinking, but yeah, those are normal pressures, i was at the time, judging by the fact that the pump pushes 80-90, but forgot about the fact that MOST of it is returned to the tank, so with that, i think the regulator is working correctly. one of those "DUH" kind of things though, i didn't have the mas airflow sensor hooked up, so i'm going to go in there and hook it up, plug the -known- vacuum leak and see if that helps. lol if it does, then, under the car i go to keep welding up the exhaust. i'll update this if those two things worked.... be right back!!!!

 

Sounds like VATs in the LT1 computer is kicking your injs off.

And you should buy your fuel pumps from Racetronix not AZ.

 

nah, the vats works fine,

i did have the mas airflow sensor hooked up, but, the tube wasn't connected to the intake... so i plugged it in, fired it up and it died a few times, now runs like a champ and sounds like a freakin dragster. i am finishing up the exhaust tonight,

then i have to find a place to mount some things, finish up some tubes, make the wiring look pretty, and it'll be on the road!!!!

definitely a good start..

as for racetronix, yeah, they are awesome, but... i'm not building a dragster, so a 67$ fuel pump is better to me than a $230 one at this time.

It's a bone stock motor, bone stock transmission, bone stock suspension, bone stock rear end, bone stock everything. no reason to throw a b@d@$$ fuel pump at it until i start upgrading things on it.

and even then, the AZ one will handle a bit more than i'm throwing at it currently.

lol don't take offense, but when i hear "you shoulda bought this instead" it always reminds me of

"well i put an LT-1 in my car"

"psh... You shoulda put an LS-1 in it instead"

"I put an LS-1 in my car"
"pshh.. you shoulda put an LS-7 in it instead"

"I put a 2000 horsepower 600 cubic inch alcohol motor in my car and am using two edelbrock 1150 cfm carbs on top"

"psh... shoulda used Holley"

hahahaha can -never- win...

with that said, i'm a builder on a budget, so 67 vs 230 or even 199, i'm going to go the standard normal every day way. I don't REALLY plan to soup this car up anymore, just drive it and sell it after a while, and let someone else do all the souping and lose their butts on it financially.

 

I understand the buget thing but I will spend the extra bux on something like a good pump because I don't want to be changing them out every other year or so.

And, yuup, ya need to have everything hooked up on these new motors b4 you try and start them.

 

ugghhhhppffhh yeah...... yeah.... you have a point there. I dont ever want to have to pull that stupid tank out again.

actually... i cheated and cut a hole in the trunk, but, someone who was helping me broke the fuel gauge thing, and i ended up having to pull the tank out anyway, at which time, i welded the hole back up. I planned to rivet it back with a gasket anticipating having to mess with the tank again in the future.

was a decent thought, and in practice was great....... until it wasn't, and i had to yank the tank out anyway... -_-

anyway, i think this thread is solved for the moment, if i have other issues i'll post a new thread, and hope that sometime in the future, this will help someone else lol.

thanks for all of the responses!