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Old December 23rd, 2017, 10:55
sdspearo's Avatar
sdspearo sdspearo is offline
NAXJA Member
Join Date: Mar 2011
Location: Encinitas, Ca
Posts: 560
Re: Fuel check valve?

Well to answer my own question, yes, there is a check valve in the fuel filter/regulator.

I found out the expensive way. The jeep wasn't holding fuel pressure so after isolating the leak between the fuel rail and the tank, I assumed it was due to a leaky check valve in the fuel pump. Dropping the tank and swapping in a new pump didn't fix it...doh! Ended up swapping the filter/regulator this morning and now holds 50psi and starts right up on first crank.

To Test:
The filter/pressure regulator has 3 ports. The two on one end are the inlet from the pump and return to the tank. The one on the other end is the outlet and feeds the fuel rail. The check valve is between the fuel rail port and return port. You can test the check valve by blowing into the outlet port with your mouth while blocking the inlet with your finger. There shouldn't be any air leaking out thru the return port.

Wish I knew this before automatically assuming a bad check valve in the fuel pump.
'96 XJ: Locked up D44's on 35" BFG's, ChroMo axles, 6" lift w/ 3 link front, 4 link rear, 4:1 Terra blow, Internal cage, DIY beadlocks, hydro assist, big ass stinger!, ...
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