Guest bastaad525 Posted February 12, 2004 Share Posted February 12, 2004 fuel pressure... what is stock fuel pressure supposed to be on a 280ZXT motor? Both with the vacuum reference connected, and disconnected? I was under the impression that it should be around 35psi with the vacuum connected, and 40 or so w/o. Then I called JWT and the guy there said that was WAY too much pressure, that I should be at more like 33psi and 36psi, connected and disconnected. he said this is an indicator that my FPR is worn out and that may be why my car runs so rich in the midrange... I tend to disagree... if only because I've seen some other dyno sheets with the exact same fuel curves from similiar setups.... unless everyone else is also running bad FPRs? Guy didn't seem to know what he was talking about but whatever... can someone here verify what my fuel pressure SHOULD be please? Quote Link to comment Share on other sites More sharing options...
Afshin Posted February 13, 2004 Share Posted February 13, 2004 Yup, fuel pressure at idle is about 32-34 and jumps up to 35-37 with the vaccum disconected. If the pressure is off by a few lbs it should not affect the running of the car (off course if it's low it may detonate sooner....). Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted February 13, 2004 Share Posted February 13, 2004 mine runs a bit higher... 34-35 with the vacuum connected, 40psi with it disconnected. And still it runs lean above 5000rpm, WITH an upgraded fuel pump... at least now I know why it runs so rich when cruising off boost. Quote Link to comment Share on other sites More sharing options...
Afshin Posted February 13, 2004 Share Posted February 13, 2004 I don't think that your fuel pressure being a few PSI high should cause the car to rich enough for you to notice. If the car is really running rich, it's most likely something else. Try spraying some cleaner on your ecu connectors and on the head temp sensor unit. ALso check vaccum lines afterwards. I assume timing is correct, if not it can cause the car to run rich. Quote Link to comment Share on other sites More sharing options...
Guest obso Posted February 13, 2004 Share Posted February 13, 2004 I don't think that your fuel pressure being a few PSI high should cause the car to rich enough for you to notice. yeah you wouldnt notice 3-4 lbs difference in fuel pressure. ive raised mine ~15lbs from stock and dont notice a difference other than it doesnt ping when the boost spikes now Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted February 13, 2004 Share Posted February 13, 2004 Fuel pressure at idle with the vaccuum disconnected should be 36 psi. It will probably drop to about 30 when you hook up a vaccuum source. Usually when your fuel pressure regulator goes bad, you will have way to much pressure at idle, and if you are lucky, your car will run, most of the time it won't. I had one go bad in the entire time I have been fooling with Z cars, so don't suspect it automatically. Also, you could have a few psi variance depending on the quality of your gauge. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted February 14, 2004 Share Posted February 14, 2004 I dunno.. I can definately notice a difference in the quality of the idle if I squeez down on the return line and cause the pressure to go up a couple PSI. Also, I know when we found the return line was too small for the better fuel pump, it caused the pressure to run at 60psi all the time, and man the car ran like crap throughout the rev range. When I installed an adj. pressure regulator on my N/A ZX to help with it running lean due to me building a high compression motor, running a cam and such, we only turned up the fuel pressure 4 psi and man it made a HUGE difference, very noticeable, ended up adding more than 10 ft lbs of torque when we tuned it on the dyno. A few psi can make a difference... Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.