Archived missing at idle

[dcoffman]

my "99 runs fine but at idle fuel pressure rises to 25 psi and engine developes a slight miss..Does anyone have any ideas. "99 with 240000 on the clock. VP44 was replaced 6 years ago, but still have original injectors. . I have ddrp fass system.

 

[JR]

Do you have a CEL?

The lift pump pressure is a little excessive. It's always a good idea to verify pressure with a manual gauge, then figure out why your lift pump is putting out excessive pressure. I'm going by memory but I believe the DDRP pumps have a spring and ball to regulate return flow to the tank. Could also be the overflow valve on the VP, but generally they fail the opposite way.

 

[Joe Mc]

From my recollections the vp doesn't like more than 22#. As far as the miss might be an injector or ???? Might want to have them pop tested.

 

[Missouri Mule]

With the original pump it should have 14 to 16 psi at idle. The ECM controls amount of fuel supplied to vp44.