hey guys, looked all over the internet and cant seem to find anyone with the same problem. My fuel pressure seems to be inconsistent. i set it to 45 psi and after driving for a wile it will either be higher or lower by 5 to 15 psi. ill hop out of the car and set it again at 45 psi and it will change again after driving for a wile. i just got the car together and dynoed and really dont want to blow it up just yet.

fuel system is as follows

2 full blown 340 fuel pumps
full blown dual hanger
8 an feed
6 an return
full blown fuel filter
full blown extra large fuel rail
full blown regulator
id 1000cc injectors

im not sure what can be doing it. the intire engine and fuel setup is brand new. not sure what can be causing this problem. im running 1/4 push lock vacuum fittings plumed into the stock vacuum port for the fpr on a golden eagle intake manifold. car idles at 900 rpm using a 1/8 inch vacume hole in the intake mani. throttle body set screw is removed so throtle plate is close and the iacv does not work with the golden eagle intakes without some fabbing. not sure if that has anything to do with it. im lost lol. any ideas?

 

regulator sticking? something blocking the return line, or maybe the voltage to the pumps is acting up, causing them to run hi/low

 

Check the voltage to the pumps and make sure it's consistant. I did a homemade boost-a-pump on mine so it stays right at 14volts all the time.

 

hmm. shouldnt the fuel pressure stay the same even if the pumps are fluctuating voltage. if im running two fuel pumps and my fuel pressure regulator is set to 45 psi and the car is idling and one pump turns off would the fuel pressure regulator not still be 45 psi?

 

what wiring do you have going to your pumps?

 

im running the pumps hard wired. 10 gauge wire from battery with 30 amp fuse to a 40/30 amp relay. running a small oddyssy 545 battery

 

faulty gauge?

 

i was thinking that. its so hard to really tell. messing around with fuel pressure is dangerous business. its a wet fuel pressure gauge, came with the full blown regulator. i originaly primed the pumps which shot up to 80 psi and the gauge was leaking where the lense and metal meet. once i lowered the pressure it leaked for a tiny bit and then stoped. the gauge is still full of fluid.

 

Bad gauge. Get one that is not oil filled. Oil filled gauges are sealed and the pressure displayed can change based on temp.

Only use a liquid filled if the needle moves a ton and you can't read it.

Just put this one in the car so I can't comment on its reliability but it seems to be good quality and not too expensive.
http://www.summitracing.com/parts/AEI-15633/

 

Or vacuum issues after temps rises - commonly adjustable regulators are the issue though, rarely the pump but it does happen...

What brand gauge do u have?