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

 

Roughly 30 PSI is a normal idle pressure for a 98 or earlier Explorer. The pressure at wide open throttle acceleration (zero vacuum to the regulator) should be around 40 PSI or so. After the engine is turned off, the check valve should retain rail pressure for awhile but not indefinitely.

 

thanks, i've been having problems with hard starting when she's warm, gotta crank her over alot like an old carborated engine, but once running runs normally. In the morning first time starting she fires right uo. i've changed the temp sensor and the IAC unit. any more ideas?
thanks