low fuel pressure issue

[Ahut2000]

I am having a problem with low fuel pressure. It's not like my pressure is way too low.. the car drives but not enough fuel is being delivered for full boost/WOT. The car will misfire and stutter.

Pressure at idle should be 38psi but i'm getting from 35 all the way down to 30psi sometimes.

the fuel pressure regulator appears to work as it should. When i remove the vacuum hose the pressure goes up as it should, and there is no fuel evident so the diaphragm inside seems to be functioning. It holds pressure as it should when the car is turned off.

I have checked all the fuel lines and replaced some. I have seafoamed the tank and that doesn't seem to fix the problem. i have inspected the sending unit and put in a new gasket, and there do not seem to be any particles in the tank clogging anything up.

The fuel filter is not clogged.

The fuel pump is a pretty new MSD 255lph external pump so I can't think of anything else besides just replacing the pump yet again.. any thoughts. It is getting 11.7v at idle and I know that's not 12v but it seems to be within tolerance for not causing an issue..

[mikeroy420]

Sounds like you checked everything. Is it possible you have a faulty injector/injectors? Check the o-rings on your injectors as well a resistance check. A bad seal around your injector or miss firing would cause a fuel pressure drop. Hope this helps

[Ahut2000]

Sounds like you checked everything. Is it possible you have a faulty injector/injectors? Check the o-rings on your injectors as well a resistance check. A bad seal around your injector or miss firing would cause a fuel pressure drop. Hope this helps


the injectors were cleaned and flow tested and put in with new o rings. The car was running perfectly with these injectors after the service at one point in time. So i'm not sure.

[JDMRIDDAZ]

THE 11v to fuel pump is issue
rewire it with heavy duty wire a relay and allow power to come from battery
why is the pump external...
is the other pump in fuel tank?

[Ahut2000]

THE 11v to fuel pump is issue
rewire it with heavy duty wire a relay and allow power to come from battery
why is the pump external...
is the other pump in fuel tank?

it's an 83 maxima, always had an external pump. I will try a bigger wire. I am using a new fuel pump relay with a 12 gauge wire but I can try a 10

[VNG704]

Is it possible electrical load robbing power from fp? Are you still getting that 11.7 or close to that under load?

[JDMRIDDAZ]

it's an 83 maxima, always had an external pump. I will try a bigger wire. I am using a new fuel pump relay with a 12 gauge wire but I can try a 10
oh ok wat i meant tho is to rewire it outside of factory wire
to insure it gets full voltage

[Ahut2000]

I rewired the fuel pump today and now i'm getting 12.1V at idle instead of 11.7V but it hasn't fixed the problem. I dunno how to check while the car is under load... haha. I just have a multimeter.

This didn't do jack though... the car is idling at 30psi and stock it's supposed to be 38psi. The FPR is functioning properly. I guess I'm going to try the pump from my other car on this one... I really can't think of anything else.

The rail holds pressure when the car is turned off so i don't think it's the fpr or the injectors but not sure..

[AdrenalineS14]

huh maybe i should check my FP too.... cause im getting misfire/fuel cut going into WOT too at around/rear 4k rpms:'( someone was saying that maybe one or more of the coilpacks are going bad idk cause my car drives just fine under 4k but sometimes i get this mysterious "cutoff" motor dies when im slowing down to a stop:'(.... i just replaced my plugs too

[Ahut2000]

dude my coilpacks were so bad my car would literally barely move under load LOL. Replaced them with new packs and coated them in liquid electrical tape and they have been perfect