fuel pump pressure question

[paddd]

I have a 97 ford explorer with a 4.0 engine, I recently tested the fuel pump pressure and I got a reading of 33 lbs, then with the engine off for 5 minutes it held it's pressure, but later fell off. is this a normal pressure or what is a normal pressure setting? should I look at replacing the pump?
thanks

[RickDaTuner]

Fuel pumps always loose their pressure over time thats not a real concern. This is why engines always prime the fuel pumps before they start. Some cars even prime the fuel pump the moment you open the drivers door. However this pressure loss takes time, over a few hours. if you are seeing a pressure difference of 15-20 psi over a 5 min period this indicates a leaky injector. granted your fuel pump is not the culprit for the pressure drop

As for you fuel pressure... 30lbs sounds low, it should be anywhere from 50-80lbs from what I remember off the top of my head. Defenitly needs to be replaced if this is the pressue with key in the on possition and the engine not running.

Pressure should keep steady as the rpms increase. If you see a steady deline to 15lbs or less as engine speed increases, then your pump needs to be replaced aswell.

[sr20s14zenki]

30 lbs does sound low, but every manufacturer does things different dont they? On my sr20det, 38 psi is normal pressure at idle. Are you having stumbling issues?

[RickDaTuner]

Specs for the 4.0l is 52 to 74 psi at idle.... Just double checked. Change the pump

[sr20s14zenki]

Originally posted by RickDaTuner
Specs for the 4.0l is 52 to 74 psi at idle.... Just double checked. Change the pump

Nice

:thumbsup:

[paddd]

thanks guys