fuel pressure problems - NJFBOA - Home of New Jersey's Camaros and Firebirds

usp55 · 09-16-2009, 07:28 PM

ok so month back i was having very very hard starts and couldnt hold fuel pressure. was like that for ever but then i changed the fuel pump and that fixed everything, car stated right up every time for the better part of 4 months since. Now the past few days i started having hard starts again...wtf. also a less that perfect idle. A little low and slightly erratic at times.

I hear the pump prime just fine, pressure goes up and started to drop just like that. So i thought maybe the fuel pressure regulator went bad. pull that off (managed to snap a screw in half - ****) look at it and the diaphragm looks fine, no holes no nothing. either my check valve went again on the new pump after only maybe 5k miles. or what - leaking injector? The engine was rebuilt just over 30k ago. i would hope an injector would make it longer than that. Now i have been running a higher psi via an adj FPR but not much higher and only cause of the cam in the car.

any ideas?

S.J.SLEEPER · 09-16-2009, 08:10 PM

if the vacuum line to fpr has fuel in it than the fpr is bad.
clamp off return line to tank and then check fuel pressure,
if pressure stays up than you know the pump has failed.
if pressure still drops than possibly a leaking injector.

was it a gm pump, aftermarket performance pump
or a aftermarket carter/airtex/ replacement pump?

usp55 · 09-17-2009, 05:23 AM

gm stock replacement pump

no fuel in the little hard vac line coming off the AFPR

S.J.SLEEPER · 09-17-2009, 12:54 PM

i am sure you checked for leaks correct? a small leak will cause a pressure drop.
if no leaks then proceed......

pull fuel rail off leaving it still attached to fuel lines. will looking @ the injectors spray nozzles, have someone cyle the key on....... wait for dripping injector..

also.... this was a complete gm pump module correct?(housing,wiring,pump, lines) if not and just changed the pump it self you could have a ruptured feed line from module housing to pump

let me know what happens from there.

usp55 · 09-18-2009, 08:03 AM

hey thanks for the help...so i didnt get time last night to look at it but did a quick check for any sort of leak. The fuel filter is covered in old black gas, cant even see any of the silver filter it self. its was ever so wet at the top connection. so there has been a leak there but for a long time. not sure why its leaking but thinkning i might have to 1 replace the filter for good measure and 2 the connection on top might be bad, stripped, something. tried to look for that line but im not sure what type of connection it is, i know it screwed in. so i have to start there

now i would love to somehow pit theinline filter under the hood somehow but not sure. would make that so much easier like my firebird. is that possible? put in a hard line where the filter normaly is, but then not sure with line under th hodd to put it in - three lines, all fuel i think coming out of the driverside fender.

Blacdout96 · 09-18-2009, 09:15 AM

You could, but that involves cutting those nylon lines and use quick disconnect fittins on the ends, it's not that hard, you'd have to warm the lines up so you could slip in the fittings, ( for our repair kits you have to soak the lines in hot water for 10 minutes) but IMO, how often do you change the filter? so it wouldn't be worth goign through all that trouble to put in a filter that doesnt get replaced as often as other filters.

As for where your other filters at, did you ever smell fuel under there? and also check the O-ring, that might of went bad ( I'm not 100% sure if there is one on that fitting, it's been a while since I replaced mine, but I think there was) If theres not O-ring, make sure the threads are ok.

usp55 · 09-18-2009, 09:35 AM

yea, no i agree prob more work but a thought. I think the thread might be bad not on the filter itself but the actally fitting. now i dont remember and i wont be able to look till sunday, but if the fitting is like this ( and i cant imagine what else it would be) than ill just cut it out and replace it.

anyone have any idea what that connection looks like on the filter?

Blacdout96 · 09-18-2009, 09:47 AM

Which end, right behind me as we speak I have the fitting that goes into eith end.

usp55 · 09-18-2009, 10:04 AM

not the quick disconnect but the end from the tank to the filter, not the filter forward to the engine.

Blacdout96 · 09-18-2009, 10:29 AM

Yeah, thats right behind me as we speak, your gonna haveto cut off the flare to take the old one off, and put the new one on, or you can get our kits that have a compression fitting, you cut the length you need, cuthe old line, and use to compression fitting to join both ends, and your all set

usp55 · 09-18-2009, 10:35 AM

ok great so its the same standad fitting in the like i put in post #7. thats easy ill pick up a new like and filter tonight and do it sunday. now i hope this is my problem with the fuel pressure but i dont think it is, this leak looks likeit been there for a while. after the filter and if i still have the problem ill look at the pump.

thanks for the help - seriously thought it was gona be a pita to find the right line and connection.

Blacdout96 · 09-18-2009, 10:54 AM

nah, if you go to Advance, which they sell the same part brand that we do, the part# from us is 730-4929, im not sure what Advance's part# is, but I'll give you the upc code, it's 6476620088. hope that helps dude.

usp55 · 09-18-2009, 10:58 AM

helps a ton, ill go there. who do work for?

sweetbmxrider · 09-18-2009, 11:03 AM

you don't want to cut the lines under the hood. they aren't even deemed repairable by gm. you can cut a little of the old line back, install a new fitting, and flare the line again.

usp55 · 09-18-2009, 11:14 AM

Any product on the threads to ensure good connection to the filter. if i remember correctly no teflon tape right

Blacdout96 · 09-18-2009, 11:19 AM

I work for NAPA in Manahawkin.

sweetbmxrider · 09-18-2009, 11:29 AM

Quote:

Originally Posted by usp55

Any product on the threads to ensure good connection to the filter. if i remember correctly no teflon tape right

i never have

Blacdout96 · 09-18-2009, 11:30 AM

nope, shouldnt have to put anything, the o ring at the end of the fitting should be enough.

S.J.SLEEPER · 09-18-2009, 05:40 PM

i wouldn't put the filter in engine compartment.
1. if you have a leak than poof there goes the car in flames
2. higher heat in engine compartment you want the fuel as cool as possible when entering into engine, thats why rear location under car best cause its away from heat and gets airflow over it driving down the road.

every lil bit of help for h.p. is great, so leave it where it is