Archived overflow valve stuck open?

[willysrule]

Last night on the way home my fuel pressure went to crap... .



I have a brand new VP44 and a filterless FASS system... the fuel filter is newer as well... and the FP gauge is tapped in before the filter housing...



I can hear the FASS cycle when I turn the key but I'm not sure if it's running when the truck is started... the truck will start and run but the fuel pressure will build a little and then drop back down... . never goes to the 15 psi or so where it use to stay... .



I have read of a couple of people having problems with there overflow return valve...



could a stuck open overflow valve cause me to build no fuel pressure during driving and hardly any when idling?

 

[Bob4x4]

Last night on the way home my fuel pressure went to crap... .



I have a brand new VP44 and a filterless FASS system... the fuel filter is newer as well... and the FP gauge is tapped in before the filter housing...



I can hear the FASS cycle when I turn the key but I'm not sure if it's running when the truck is started... the truck will start and run but the fuel pressure will build a little and then drop back down... . never goes to the 15 psi or so where it use to stay... .



I have read of a couple of people having problems with there overflow return valve...



could a stuck open overflow valve cause me to build no fuel pressure during driving and hardly any when idling?

I would look at the FASS first,I have yet to have any issues with the overflow valve on a vp-44. I have changed 100's of vp's



Bob

 

[steved]

Or a faulty guage...



steved

 

[dieselluver]

I ran into the same thing on a friend's pickup. The filter was fairly new, but I changed it out anyway, and it solved the problem. He must have gotten into some bad fuel. I'd try another filter if I were you.



p. s. -take a testlight and check power right at the FASS while it's running.

 

[willysrule]

I figured it out... . and I can't believe what it was... .



First I removed the line going to the fuel filter housing and blocked it off with a plug fitting…then hot wired the FASS pump, it kicked on and built pressure…. so it wasn't the pump itself…that let back to the overflow valve being stuck open…. but I started tracing wires for the FASS before I touched the overflow valve…. Using a test light I had power everywhere and the pump was running, but wasn't running very well, seemed sluggish…so I started checking everything with a meter, the wires coming off of the battery were reading only 2 volts, even with the truck running…I knew that couldn't be right…so I pulled the batteries and took them to a friends garage to have them tested…turns out that the battery the FASS wires were hook to had a dead cell inside, so I wasn't getting a good current or full power to the FASS system…I replaced both batteries and it runs like a charm and doesn't drop below 13 psi at WOT… With all the fueling problems that these trucks have I would have never thought to check the batteries first!



Thanks for the input thou…

 

[p-Bar]

Good trouble shooting