I am just wondering what kind of pressure drop in the fuel system is "normal". I see a 4-6psi drop in .5hrs and 20-24psi drop in 1.5hrs. - Is this normal? I've been trying to track down an idle "hiccup" and a slightly rich condition and I think it might be a leaking injector.

Thanks,
Dave

 

My fuel system can hold pressure for days. I had my car in storage for over a week and it still had about 20 psi in the lines (i had a pressure guage on it).

I would take the fuel rail off with the injectors on it and then turn the key to the run position.. that will tell you if you have a leaky injector.

 

The ones I have seen with problems in the fuel pump check valve drop off a lot faster than 6psi in 1/2-hour. I would check the injectors for a drip, as suggested.

"Holding" fuel pressure isn't essential to healthy engine operation. My Weldon AFPR intentionally relases the normal 58psi at shutoff, to take the pressure off the injectors.

 

Injuneer,

I understand that drop-off shouldn't affect operation, but as I said I am trying to fix my idle "hiccup" the car has had it since I bought it. All I can think of is that an injector is not closing all the way and allowing xtra fuel into one or more cylinders. It would also explain longer start times if the car has been sitting overnight and also would explain my slighlty rich condition(blm's around 122-124) Do you think i'm on the right track?


Thanks,
DAve

 

Yes.... that's why I specifically suggested "I would check the injectors for a drip, as suggested." Not sure how I could have said it any clearer.

 

injuneer,

sorry, i wasn't trying to 2nd guess you, I suppose i was "thinking outloud" to make sure my train of logic was logical to everyone else...


thanks again,
Dave