1rad280 Posted March 31, 2009 Share Posted March 31, 2009 I connected a inline fuel gauge up to my 76 280z l28e and found my fuel pressure at idle is 100 psi.I also noticed my return line had swollen.So I took the hose off of the tank and the fuel rail then blew air from the return line to the tank and junk came out of the lines so I hooked it all back up and no change the return line is still swelling.It sounds great when you first start it and no smoke but after a few min. It start loading up with fuel and it sound like it has a big cam in it and starts smoking bad. Could there be a blockage in the tank?What should I try? What does the fuel pressure need to be?Could it be the fuel pressure regulator? Quote Link to comment Share on other sites More sharing options...
TONY C Posted April 3, 2009 Share Posted April 3, 2009 sounds like the hose has collapsed inside. Replace all the rubber hose in the system. It's a pain but worth it. Blow thru all the lines before you put the new hoses on. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted April 3, 2009 Share Posted April 3, 2009 If the return hose is swelling, then the restriction is either in the hose itself or after it. Quote Link to comment Share on other sites More sharing options...
1rad280 Posted April 3, 2009 Author Share Posted April 3, 2009 I replaced all the lines even checked the metal lines air flowes through them.what if I put a resistor at the fuel pump because if I unplug the fuel pump relay the fuel pressure goes down then the car runs fine until no fuel. I failed to say that it has an aftermarket summit racing fuel pump. Quote Link to comment Share on other sites More sharing options...
xxjoeyxxeb Posted May 10, 2009 Share Posted May 10, 2009 I am having a similar problem. I am getting about 55-60 psi at idle and when giving it gas. The car runs very hard and rough. And it chokes when I give it throttle. I am trying to clean the injectors and see how they flow, then going to try a different fuel pressure regulator and see how that works. Let me know if you find anything. Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted May 10, 2009 Share Posted May 10, 2009 I replaced all the lines even checked the metal lines air flowes through them.what if I put a resistor at the fuel pump because if I unplug the fuel pump relay the fuel pressure goes down then the car runs fine until no fuel. I failed to say that it has an aftermarket summit racing fuel pump. What are the specs on it? It could be too much for the factory return size or regulator, etc... Most EFI systems follow the standard; ~43.5 psi at 0 psi relative (ie., with the vacuum line unhooked from the FPR). If your car is in vacuum, deduct that much from the base pressure. A car that idles at 7 psi vacuum would have (43.5-7=36.5 psi) fuel pressure at idle (with the vac line hooked up to the regulator). Note to all: do NOT buy a rising rate fuel pressure regulator. A rising rate regulator is usually only put on a normally aspirated car where they're too cheap to install the appropriate sized injectors for a turbo conversion. (Rising rate increase the fuel pressure MORE THAN the increase in manifold pressure). Most standard fuel pressure regulators (for EFI) have a vacuum port and adjustable nut (to set base pressure; could be the issue here if he doesn't have an adjustable reg). Look at the typical Aeromotive regulator; they are very nice and work with a wide array of applications: http://www.jegs.com/i/Aeromotive/027/13109/10002/-1 Quote Link to comment Share on other sites More sharing options...
xxjoeyxxeb Posted May 11, 2009 Share Posted May 11, 2009 I just flow tested my injectors and only 2 of them had a halfway decent spray pattern, 1 was clogged, and 3 had a small stream. So now have some clean injectors and a different pressure regulator and we will see how the car runs soon, and how the pressure is. Quote Link to comment Share on other sites More sharing options...
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