fuel pressure

[IzaBell 280]

I installed my fuel pressure gauge in the typical spot after my fuel filter. 800RPM 28-29 psi:(, vacuum is 16 steady and timing is about 18. New fuel pump, new fuel filter, and new lines. If I take the vacuum line off the fuel pressure regulator at idle pressure jumps to 36(were I would like to be) I also disconnect the cold start connection(no change). The question is is my fuel pressure regulator bad? all OEM

Thanks.

Edited July 19, 2010 by IzaBell 280

[z-ya]

I installed my fuel pressure gauge in the typical spot after my fuel filter. 800RPM 28-29 psi:(, vacuum is 16 steady and timing is about 18. New fuel pump, new fuel filter, and new lines. If I take the vacuum line off the fuel pressure regulator at idle pressure jumps to 36(were I would like to be) I also disconnect the cold start connection(no change). The question is is my fuel pressure regulator bad? all OEM

Thanks.

 

What are you using for a gauge? I find the cheap mechanical ones are not all that accurate. I've seen 5psi difference from one gauge to another. Does the pressure increase as you open up the throttle?

[IzaBell 280]

Thanks for the reply. It does jump with the throttle--to about 35. Its an Auto Meter gauge. installed right after fuel filter. Idle is right at 30. Also I noticed that about an hour after the car is off the pressure drops to zero. Is that all common? I think I should get a new FPR...I dont know

[NewZed]

I installed my fuel pressure gauge in the typical spot after my fuel filter. 800RPM 28-29 psi:(, vacuum is 16 steady and timing is about 18. New fuel pump, new fuel filter, and new lines. If I take the vacuum line off the fuel pressure regulator at idle pressure jumps to 36(were I would like to be) I also disconnect the cold start connection(no change). The question is is my fuel pressure regulator bad? all OEM

Thanks.

 

It sounds like your regulator is fine. The fact that it is about 36 without the vacuum line and in the high 20s with it indicates that it is working correctly. The vacuum line is designed to reduce fuel pressure at high manifold vacuum (low manifold pressure). That's why it is there. My car sits at about 26 psi, warmed up and at idle, with the vacuum hose connected.

 

The procedure in the FSM has you test the FPR and pump with the engine not running. 36.3 psi means good pump and FPR.

 

If the quick leak down bothers you, that's a different issue but shouldn't affect the engine's performance. It could also involve the fuel pump (the other end of the pressurized fuel line). It's not a big deal though. My car leaks down occasionally but not often. A couple of extra cranks to get it started is all it causes.