after the engine is shut down, or should the guage stay at the position it was at when shut down? Is there a pressure release in the system? When the key is turned on doesn't the pressure drop to 3-4# at startup, then proceed to pump maximun?

My truck starts and runs fine, however I can hear a very faint hissing sound when I shut off the engine with the hood up. Sound like a very small air leak, but my hearing isn't good enough to determine where it's coming from, and it only last about 15 seconds or so.

I though about spraying some soapy water on the fuel connections to see if would show up? Any ideas?

 

On my 01, with a Carter Campaign pump, my fuel pressure is about 15psi when I turn the key to the On position. When I start the engine, the pressure drops to 13-14psi, at full acceleration the pressure drops more to about 10psi. When the engine is off the pressure is zero. My gauge is mechanical, so the readings are accurate. The fuel pump is electrical, so as soon as you turn the key off, it stops making fuel pressure.

I haven't payed close attention, but I think the fuel pressure does drop to 3-4psi at start up. However, if your fuel pressure at idle is 3-4psi, then you're in trouble! Your fuel pump is bad, you should replace it fast, before your injection pump gets damaged.

 

I bet that faint hissing sound you hear is the turbo. It will spin for quite some time after shut down, and depending on your intake, you can hear it, but barely.

 

No 24v Expert here , so i can't really help on the duel pressure issue , but as for the hissing sound , I would bet it is the A/C, It is perfectly normal for it to make a hissing sound once the truck is turned off , the sound will be coming from the engine area. The A/C also runs in defrost mode to dry the air, so whether it is hot or cold where you are , this could very likely be your problem.

 

Soapy water won't show a fuel leak and there shouldn't be any air leaking out of your fuel system. My truck hisses at shut down but I think its probably the A/C settling down.....or she's mad she's gettin put up for a while!