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PA CHAPTER VP
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349 Posts
Discussion Starter #1
My fuel pressure gauge has read SINCE installed the following...

10psi at idle
on throttle casually with steadily drop to 5psi

punching the throttle it will drop to 0psi

on the highway at 70mph it will be at 5psi and occasionally drop down the zero out of no where and then pop right back up to 5psi

Now at 0psi i would not be running correct? Call me crazy but i dont understand it at all since the gauge has been in it was like this. Is it my gauge or lift pump? Any help would be great!

Thanks,

Steve
 

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2,798 Posts
i think the injection pump will still suck fuel out of the tank with a dying or dead lift pump
 

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PA CHAPTER VP
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349 Posts
Discussion Starter #3
I know but the truck does seem to run fine too. I just dont get it. Anyone else have some input?
 

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If I were you, I'd re-test the fuel pressure with a different mechanical guage at the VP. Sounds like your guage is going bad. Looks like you got a good fuel pump the airdog.... unless your filters are plugged or the lines are pinched or kinked. You'd want to fix the problem before the VP gets compromised.
 

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I have the same pump as you and the guage reads 14.5 psi at all times. Check the electrical connections to the Air Dog. If the pump is working then I think the issue will be the overflow valve. That is the fitting on the VP-44 that holds the return line in place. In the attached pic it is the one to the left. If the valve get stuck in the open position it will mimic a bad lift pump. About $30 from dealer I'm told. I have a friend that just went threw this with his FASS pump. Good Luck... Chris
 

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PA CHAPTER VP
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349 Posts
Discussion Starter #6
Thanks for the replies guys, i got it figured out. When i reran the gauge lining i it got pinched. Thanks again!:peelout
 
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