Toolrocks

iTrader: (1)

I installed my Autometer f/p gauge and am noticing what I've suspected - I lose fuel pressure immediately after shutting the car off. Pressure will be around 36 psi at idle, then I'll shut the car off, turn the key to on (no start) and watch the pressure build up while the pump runs for a few secs and then watch the pressure drop quickly to 5 psi and then slowly fade. I'll need another set of hands to pinch the various fuel lines to determine which side of the fuel line is losing the pressure. If it's the pump side, do I really need to replace it? If it's not the pump, then it must be one of my injectors leaking. I don't think it's an injector problem - car idles fine and gets the same gas mileage it always has. So, I'm really suspecting a failing fuel pump check valve. WIll this valve cause problems if I leave it unfixed? Is it robbing me of some power or just causing hard starts? Sorry, I can't search (not griping) Thanks

vbxmaxima

I've seen this ever since I put on my fuel pressure gauge, but
I never thought it was a "problem". I deduced that the fuel pressure
relay kicks in the pump long enough to build pressure to let you
start the car. Most folks go straight to ignition, yes?

Since I can see fuel pressure, I just let it build to the max
and start the car...didn't seem like an issue to me.

Anyhoo, I just didn't want you to go looking for some "fault"
when there may be none to begin with. Although I'm only speaking
of my experience with my car, I've never seen fuel pressure remain
above 30psi for any considerable duration when the fuel relay cuts off power to the pump after 5 sec.

Toolrocks

iTrader: (1)

Thanks for the reply, you saved me a bump. Our cars are supposed to maintain pressure in the line for sometime. Mine drops off the second I shut the car off. According to both my FSM and the Haynes manual, this is not proper operation. Hopefully in the next few days I'll be able to determine where the pressure is escaping from. Thanks again for the reply. Hopefully you're right, if it aint broke don't....

DCmax

iTrader: (2)

I'm guessing a physical fuel pump or fuel delivery system issue. I have basically the same fuel pressure gauge you do and when I shut the car off the fuel pressure remains at the level it was when I turned the car off. When I dont start the car and turn it on accessory, the fuel pressure rises to 20 psi. I've found that the autometer fp gauge is also very accurate. As you know, I just replaced my stock fuel pump this past weekend. The first sign that made me think my stock pump was on it's way out was frequent fuel pressure fluxuations. Although I didnt have the problem you are describing, when I first had the fp guage in, it would read 37 psi and over the weeks it would degrade and degrade sometimes reaching as low as 31 psi. The new pump fixed all the problems. If you want you can try out my bunk as5 stock fuel pump.

I'd pass on the injector hypothesis.

1MAX2NV

iTrader: (5)

If one of the injector is leaking, you want to fix it ASAP. It would ruin your pistion ring in that cylinder.

Toolrocks

iTrader: (1)

Sorry, one last attempt at getting an answer. TTT. I will let the thread die after this.