Losing fuel pressure overnight

[Hbabler]

I have a stock 2001 LB7 with around 330,000 on it, I replaced the injectors about a year ago. For the last couple of months if the truck is parked in any position other than nose down it will run and then die after about 5 seconds, if I pump the primer until it gets hard it fires right back up. If I pump the primer before I crank it I also have no issues. I replace the filter head and hoses and still have had no luck, I also have an aluminum bleeder screw installed.
I believe the next step would be to install a clear hose to the cp3 to see which side it leaks down on? Any other ideas? Thanks.

 

[JoshH]

Did you replace the WIF sensor.

 

[Hbabler]

It has the new one installed that came with the complete filter head.

 

[JoshH]

What about the seals on the banjo bolts going into the FICM?

 

[Awenta]

Did you replace all the rubber lines?


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[Awenta]

Put some pressure in the tank and take a look around. Like 10psi.
Might be a good time for a lift pump


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[juddski88]

Ive replaced several cp3's that leaked by the check valve to the return side, but definitely isolate segments of lines and connections and pressure test with a mityvac to make it easier on yourself

 

[Hbabler]

Thanks for all the help and happy thanksgiving.

I decided to replace the banjo seals and it is still doing the same thing.

I could put a lift pump in it but I don't want to just cover up a problem.

To check with a mityvac would I just disconnect the rubber lines at the FICM and then check to see which side leaks down? Then I can further isolate it from there?

 

[Hbabler]

Any other thoughts?

 

[S Phinney]

Pulling a vacuum on the low pressure side would tell you if and where there is air introduced into the system. That's a good start for you. Any rubber line could be the culprit.


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