After replacing the fuel lines in the engine bay (from the filter and join under the car to the fuel rail) due to a worn hose (don't ask... It wasn't my fault and I'm just glad I found it when I did) I refilled the tank on Saturday night and turned the key with my fuel pressure guage attached to prime the lines and check for leaks.

After many turns of the key to prime the lines, I finally got it up to an 50psi indicated (I can't remember if I set it there...). Anyway, I found the pressure was dropping quickly due to the guage not being installed properly and leaking fuel as a result. After reinstalling the guage, I still seemed to be getting a fairly rapid pressure loss.

I can't start the car yet as there aren't any accesory belts installed (among other things). I can't find a leak anywhere and the only thing I seem to have installed differently is the connector under the frame rail for the fuel return line, which is installed the other way around to how it was originally installed, as far as I can see, there is no way that fitting has any function other than that of a connector.

My question is: Is the quick fuel pressure loss the sign of something being amiss or is it because my fuel systems was dry and the pressure loss is due to the fuel ditribnuting through the system? I'm not sure if my gauge is damaged or if I have a problem...

 

Pull some spark plugs to see if you can smell raw fuel on any of them. This will tell you if you have a leaky injector somewhere. If you don't smell any fuel, pinch or cap off the fuel return line coming from the pressure regulator, prime the system again and see if the pressure continues to drop. If the pressure still drops off quickly, then suspect a bad fuel pump. If the pressure stays, then you have a pressure regulator that is bypassing and should be replaced. Now all this is assuming that your gauge is correct and you don't have any external fuel leaks. Hope this helps and good luck.

 

Thanks. Looks like I have a few things to try tonight. :)

 

Symptom
Upon restarting an L98 after it has been standing for a while it cranks for a longer time than if
started when totally cold or very soon after shutting it off.
Test
Before starting the warm engine, with the ignition key off, hold the accelerator full open for say
30-60 seconds.
Release the accelerator, and start the engine.
If it now starts quickly, the problem is a leaking fuel injector.

 

I couldn't keep fuel pressure in my IROC, but the car ran fine. After a while the fuel pump bit the dust and after I replaced it I was able to hold pressure. Moral of the story: An ailing fuel pump can cause pressure to bleed, but because it still keeps pressure while it's pumping, it's pretty transparent.

 

which part of the diagnostic link do you energize to engage the pump?