Maxfreak

Does anyone know a way to check for proper fuel pressure? This is in regards to sluggish performance. I'm wondering if my fuel pump is not working right.

1MAX2NV

iTrader: (5)

You will need a fuel pressure gauge. I think you can pick one up at your local auto parts store. Hook it after the outlet of the fuel filter to check your fuel pressure. Nissan fuel pump rarely goes bad even on high mileage car. I would try a tune up. Change your air filter/fuel filter. Maybe steam clean inside of your engine.

MardiGrasMax

iTrader: (14)

36psi at idle
43psi at WOT

Maxfreak

Could low pressure at WOT cause poor preformance, and how often does this happen?

MardiGrasMax

iTrader: (14)

Yes it could.

This is a job for Daniel B...

But how old is your fuel filter? It could be cloged.

Their are other things that can cause this.

Did you all of a sudden notice the loss of power or was it gradual over a few days or weeks?

NYCe MaXiMa

iTrader: (9)

What can be causing wrong pressure? I have problems with fuel consumption and I checked my fuel pressure, it was hanging around 37 or so at idle and didn't change at WOT, I went ahead and replaced the fuel pressure regulator and the thing is still virtually the same...
I did the test described in Chilton's and it said to pull the fuel pump fuse, start the car, wait till it stalls, attach fuel pressure gauge and measure the pressure with ignition on and engine off... then start it and measure it again... I don't remember exactly what the numbers were supposed to be but they were wrong and stayed wrong after the new FPR. What else can be causing incorrect fuel pressure? I checked some of the rubber hoses leading from and to fuel filter, regulator, manifold or whatever and I replaced 2 of them which showed signs of wear or were really dry.. I still get ****ty *** gas milage and I don't know if my fuel pressure is sufficient. Car runs like **** too... very sluggish

So what else can be affecting fuel pressure?

Fuel pump?

Daniel B. Martin

This is a standard diagnostic test. You will find instructions and a diagram or picture in Chilton (page 5-3) and Haynes (page 4-3,4).

Bleed the fuel rail pressure by pulling the fuel pump fuse and making several attempts to start the engine (it won't start). Install a T-fitting with a pressure gauge in the flexible rubber fuel line just downstream of the fuel filter. Install the fuel pump fuse. Start the engine. You should see the pressure maintain a stable 34 psi. After turning the engine off the fuel system should hold pressure for a long time, 24 hours or longer. If the residual pressure bleeds off in only one or two hours that is a sign of a problem... bad fuel pump check valve, injectors with an internal leak, bad fuel pressure regulator, or an external fuel leak.

Daniel B. Martin

The Fuel Pressure Regulator has a vacuum hose input. With high vacuum (engine idling) the FPR delivers 34 psi. With no vacuum (disconnect and plug the vacuum hose) the pressure should go to 43 psi.

I don't suspect a weak fuel pump. If you do, you could momentarily pinch the fuel return line closed and this should cause a healthy pump to increase the pressure to well above 43 psi.