Engine/Transmission (1998.5 - 2002) Pressurized Fuel System After FASS Installation

[JDriscoll]

I installed a FASS HPFP on my truck this weekend after the old lift pump started heading south. Along with the pump, I put in a draw straw and new lines. Everything is running fine, but now my tank is pressurized. I drove from my house to work this morning (about 6 miles), and when I shut the truck off I could hear a hissing sound comming from the tank. I opened the fuel cap and the pressure almost blew it out of my hand. It seems like it is way more pressure than the pump is capable of. I should also mention that this morning is the first time I filled the truck since I installed the pump.



I did a search for old posts, and found quite a few. It seems like replacing the copper washers on the injectors fixed the problem. My question is where can I get a set of washers, and how hard is it to replace them. Does anyone have any other ideas as to what could be causing this?



Thanks,

John

 

[aircop]

Can someone tell me how changing injectors copper washers would help this problem.

 

[Arkansas Traveler]

Well, no one else is answering so I gonna guess that compression could be leaking past the copper o-rings and entering the fuel drain from the head back to the return to the fuel tank. I dunno. . anybody else?

 

[GarrettPetersen]

I believe that the roll over protection valve is not funcitioning correctly so now the tank aint venting properly. Its creating a vaccume inside the tank.

 

[JLandry]

John,



So this problem only started with the installation of the FASS HPFP... right?



Probably a long shot but...



Could the FASS be sucking in air somehow and then that air is working its way back to the tank through the fuel return line?



Could the internal vent in your fuel cap be stuck? Maybe try installing a new fuel cap first before doing anything more drastic.



Good luck,



John L.

 

[JDriscoll]

This problem did start with the FASS install, and the tank is under pressure, not vaccum. Just the amount of pressure that built up in such a short time makes me think it is comming from engine compression. I cleaned the roll-over valve and checked the vent for kinks, anyone one else have any ideas?



Diesel-Dan have you heard of this before?

 

[JLandry]

I cleaned the roll-over valve and checked the vent for kinks

The roll over valve lets air in and isn't supposed to let air out... right? Excessive pressure in the tank is relieved through a check-valve in the fuel tank cap. The cap can be disassembled (well, at least aftermarket ones can - not sure about the OEM cap) and the spring for the check valve removed which causes the cap to be freely vented.



John L.

 

[JDriscoll]

Problem solved! I replaced the copper washers on the injectors and everything is running great. I give FASS customer service high marks on this one. Thanks again for all of the advice.

 

[LowFly]

Cool... . didn't I talk to you on the phone about this? Them copper washers can cause some issues... and i have seen it more and more these days... glad you got your issue figured out.

 

[JDriscoll]

Yes that was me on the phone, and I wish I would have swapped out for some better injectors at the same time. Everything is working great. I really appreciate the help on this.





John