fuel pressure on a 97 xlt?

[tnmnone]

I've had some starting problems that i think is linked to my fuel system. i checked the fuel pressure on the fuel rail and it read a hair ocer 30 psi. whats the pressure suppose to be?

 

[aldive]

On my '99 , the specs are 65 +/- 8 psi.

 

[tnmnone]

thats big diff that what i read, would it really be that big of a diff in only a 2 year period?

 

[Hartman]

Do you have an OHV or SOHC? The SOHC has a much higher fuel pressure because it has a returnless fuel system I think.

I know mine is at 30 PSI at idle and 35 when it's warm.

 

[tnmnone]

it a sohc 4.0L, at idle its 30 and when i revved it it only went up a few psi, not much

 

[RickOTR]

What does the pressure read when you disconnect the vacuum hose from the regulator. I get 32 psi at warm idle, 40 psi with vacuum hose disconnected, and with key on engine off.

 

[tnmnone]

i haven't done it that way yet. doesn't the key have to on but the engine not running to take the reading? with it like that i read 20 psi and with the engine running it read 30 psi. but i had the vaccum hose connected

 

[aubtc]

I have a 96 XLT with V8 and the manual implies that the fuel pump only operates when receiving a signal that the motor is turning (i.e. crankangle sensor, crank sensor, or something, not sure which one it looks at). This causes problems for me, because I slowly loose fuel pressure when motor is off and have to crank for a few seconds to build pressure.

 

[Opera House]

With the engine off the initial pump charge should take it up to 39# and keep it there long enough to read it. Should stay over 30# for at least 30 minutes. The vacuum line drops the pressure by whatever the vacuum is, typically about 7# to 32-33 at idle. With your 20# reading, you obviously have a leakdown problem in the pump check valve, injector, or fuel pressure regulator.