BayAreaZT Posted October 2, 2003 Share Posted October 2, 2003 I finally got around to putting in a fuel pressure gauge on my car because I've been having problems with the car being sluggish under heavy loads. This is a 83 l28et with stock fuel system and new fuel filter. I should be reading around 36psi but I'm only at 29psi. I plan on re-wireing the fuel pump to the alternator with 10ga wire and a relay but will this raise my fuel pressure or could there be a problem with my fuel pressure regulator? I also noticed that my fuel lines coming in and out of the fuel filter was 5/16" and not 3/8" like I thought. I changed the line coming out of the filter to 3/8" but left the feed line at 5/16". Could this change in diameter cause that much of a pressure drop? Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted October 2, 2003 Share Posted October 2, 2003 I finally got around to putting in a fuel pressure gauge on my car because I've been having problems with the car being sluggish under heavy loads. This is a 83 l28et with stock fuel system and new fuel filter. I should be reading around 36psi but I'm only at 29psi. I plan on re-wireing the fuel pump to the alternator with 10ga wire and a relay but will this raise my fuel pressure or could there be a problem with my fuel pressure regulator? I also noticed that my fuel lines coming in and out of the fuel filter was 5/16" and not 3/8" like I thought. I changed the line coming out of the filter to 3/8" but left the feed line at 5/16". Could this change in diameter cause that much of a pressure drop? The re-wiring will not affect your fuel pressure, and neither will the 5/16" line. The pump with standard wiring will dead-head at 70+ psi. The stock fuel lines are 5/16", supply and return, and that's what I'm running with double the stock horsepower. If your vacuum line (manifold reference) is attached to your regulator when you measure the pressure, 29 psi is right on the stock value. To check baseline, which should be 36, unhook and plug the line (not the port) at the regulator. Quote Link to comment Share on other sites More sharing options...
Afshin Posted October 2, 2003 Share Posted October 2, 2003 Fully agree with SleeperZ. stock runs about 29-32psi and usually jumps about 4 psi when you disconect the vacuum hose to the pressure regulator. Quote Link to comment Share on other sites More sharing options...
BayAreaZT Posted October 2, 2003 Author Share Posted October 2, 2003 Thanks guys. I'll try that tommorrow. Quote Link to comment Share on other sites More sharing options...
Guest Zcarsmakemyheadhurt Posted October 3, 2003 Share Posted October 3, 2003 Get rid of the junk stock pump, use at least a MSD. Quote Link to comment Share on other sites More sharing options...
VinhZXT Posted October 3, 2003 Share Posted October 3, 2003 I had this same problem with my spyderZX. It turn out that the fuel feed line from the gas tank was half clogged. This is the line that connects to the fuel sending unit on top of the gas tank. I guess what happen is the car sits too long with little gas in the tank and it start build up in the line. Also there is a little filter-screen at the feed line and it too has a thin layer of film on it. I used a wire brush and gently clean it up and the car idles at 32 and at WOT it's 36. Hope that helps Vinh Quote Link to comment Share on other sites More sharing options...
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