Potential fuel pump problems

[vetteboy86]

I checked my fuel pressure yesterday, and I coudln't get an accurate reading because the needle bounce was terrible. I was told that the ground strap for the fuel pump could be loose, causing the fuel pump to cycle on and off erratically.

What would cause this needle bounce? How do I check to see if the fuel pump is good?

 

[tigmaned]

how many miles on yours, have you ever changed it? there pretty cheap ($50 or so) and pretty easy to take out too. did you try clamping the feed and return lines to see if that changed anything with your FP.
i chaned mine because my sending unit was all rusted out, so while i had it out i figured put a new pump in. my FP was seady at 39psi. but i am getting a quick drop to 22psi at shut off. so every one is say change the injecters now. still chasig a gas smell too??

 

[vetteboy86]

The fuel pump is the original. How would I clamp the steel lines??? without ruining them.

What does the fuel pressure dropping off to 20 psi after the key is off have to do with the injectors??? Think they are leaking??

 

[tigmaned]

when you pull the rubber boot out from around the fuel filler you will see the rubber ends of the fuel line, the top one going to the right is the feed and lower one comng from the right is the return line. all fuel lines have rubber connection along the route to the engine so they can flex.
not sure what my problem with the drop to 22psi means yet, some have said a open in the system some have said bad injectors. i have had the vette since march so i have no idea if they are the stock ones or not?? i am just have till Dec for my next emissions test to pass.

 

[Agent 86]

Do you have access to another gauge ?? Maybe the gauge is a piece of crap

 

[sxyvet]

hi there vetteboy86,
i recently just purchased a screw on type fuel preasure guage which did not have the oil/liqiud inside it and with in 6 weeks it stuffed up and was not reading rite preasure and was very un acuarate!
i returned it to the auto shop and they said the spring went inside ,which was stuffed!
so then i got the better option which they did not have in stock at the time, but this new guage now has a specail oil/liquid of some sort which stops the bounce/inacuarate reading and now is just working fine 4 months later down the track!
just a thought for you guys to think with!
cheers
glen sxyvet-australia

 

[vetteboy86]

Thanks for the responses. The only thing that concerns me is that when hooked up to my brothers car, it reads fine. Minimal needle bounce, and is very accurate. I dont know if this is a condition with the new fuel pressure regulator or not.

 

[Agent 86]

Diaphram right side up ??

 

[vetteboy86]

Yes, there is really only one way you can put it in, without having clearance and fit problems.

Well here is a development. I put the guage on before I started the car, and it had been sitting for a day. Started it up, and the fuel pressure needle was very steady, hardly any fluctuation. Noticed that it wasn't on very tight, so I took it off, wiped up the little gas that seaped out, put it back on tighter, and now I have the needle bounce again. So I am wondering if that pintle or soemthing is not making a good fit.

 

[tigmaned]

are you useing a test fuel perssure gauge or one that stays on the car all the time now? i never used one of those, i have a tester style gauge. could there by air or some thing you have to bleed off the gauge??

 

[vetteboy86]

The guage is one that screws onto the schrader valve. It is not a permanent guage.

 

[jiangtao]

I am still tracking down the same problem of a fuel smell when I take my foot off the gas and coast. Still have the famous hard starts when warm also. My MAF recently bit the dust and I replaced it and it wouldn't start so I wiggled some wires at the fuel door and then it cranked right up. Got to looking and noticed that when my dad put the new fuel pump on {5th one in 2 years} he never hooked up the harness right{just stitting in there not fully in} The car has more power now, but I still get the hard starts. I am also in the process of changing every line to the vapor canister as I still have gas in the purge vavle down there. One question though. Were can you get the rubber lines that come from the fuel door area? Mine are split in some places and I noticed that they aren't just regular hoses as they have a metal fitting that join to the metal lines.