Engine/Transmission (1998.5 - 2002) Fuel System Pressurizing (FASS????)

[rkressg]

I am having an issue with my fuel system pressurizing while driving. I believe there is a vent somewhere in the system to allow the fuel tank to breath, but I am not certain where it is.

2001. 5 ETH, I have a HR VP44, there are no fuel leaks that I can find (excluding what happens below).



I have replaced the Roll-Over valve on top of the tank.



I have a FASS 150 GPH, with 1/2" fuel lines (including 1/2" pickup in tank). I have a separate 3/8" return to the tank from the FASS, not using the fuel fill neck.



If I leave the gas cap on tight, fuel will begin to spray out of the fuel neck, if I leave the gas cap loose, this does not happen, but I can see vaporized fuel coming out of the fuel tank. For some reason, the fuel system (tank) appears to be pressurizing.



I know that this has been on here before as an issue, but I can not remember the resolutions.



Is there another vent on the fuel system somewhere? Possibly on the FASS???

 

[Highfinance97]

Could the fuel cap be faulty and not venting???


Michael

 

[Thomas]

Have you done an injector removal/install lately?

 

[WTBurke]

At the top of the in-tank canister (sender draw-straw unit) where your fuel delivery and return lines attach you will find a nipple (breather-vent) that is WIDE-OPEN. This allows dirt and debris to enter your tank. Most of us have added a small line with a cheap fuel filter and extended this up-hill to the fuel filler neck to prevent slosh and deep-water crossings won't allow water to enter your fuel tank. IF that nipple is clogged or blocked off perhaps this is what you're referring to. It's an easy fix and the vent-nipple shouldn't be left open to draw dirt into your tank... . why DC did this is beyond me?



William

 

[Thomas]

. . . a nipple (breather-vent) that is WIDE-OPEN. . .

This is the rollover valve which the OP states was replaced. You are correct in stating that it is normally open to the atmosphere. I doubt that "Most of us" have added anything to that vent.

The same fuel filler cap is used on all 2001 Ram trucks, regardless of fuel. The cap has vacuum/pressure operated valves (required only by the gasoline engines).

The "fuel will begin to spray out of the fuel neck" & "I can see vaporized fuel coming out of the fuel tank" suggest to me that a fair quantity of air is being pumped into the tank—likely by the engine.

 

[WTBurke]

I've had my canister out because of a modification. This nipple-vent is WIDE-OPEN and there is an old thread that covers this subject. I will re-word my statement that "many of us" have modified this vent because it does indeed allow un-wanted material to enter the fuel tank and an inexpensive plastic encapsulated fuel filter will prevent dust from entering the system.



My tank does not pressurize in my CTD however; my 1990 Gas Chevy does.



William

 

[rkressg]

Thomas,
I would venture to guess that it is coming in from the engine some how (though I have no idea how).

I replaced the roll over valve, but it made no difference. The roll-over valve worked like a 1-way check valve, which only allows air into the tank, but nothing out. Both my old and new valve worked in this fashion.
I do have a new fuel cap, but it does not vent (it appears to be sealed also).

I have not recently done any work to this truck (injector removal/reinstall). I recently pulled the tank to allow changing of the roll-over valve, but that was for this problem.

Does anybody have any idea how air could be getting pumped in from the engine?
Possibly an issue with the VP44? I have an HR VP44 with about 30,000 on it (I think I am on VP44#5 now)

Does anybody think that I could have had a washer fail under the injector? Could this possibly allow fuel to be returning and some how picking up excessive air?

Could the FASS be causing this???

Thanks,
-Rich

 

[Thomas]

There have been a few posts over the years with symptoms like yours. This one, and several others, mention an issue with the copper washer: https://www.turbodieselregister.com/forums/24-valve-engine-transmission-1998-5-2002/94613-pressurized-fuel-tank-normal-pleae-help.html. With the quantity of air you are seeing the recent injector work question seemed a good place to start.

I'm not the expert here. I just have a good memory of some of the old posts. I can't help you with the FASS. Some time spent with the site search feature may help.

Good luck.

 

[LowFly]

The one time i have had to deal with this, it was an injector sending engine compression to the tank via the return line. The copper washer on the injector was leaking.....



WHat you could do is pull the return line at the tank... and run the truck. . and see how much fuel comes out... see if you get any vapor/mist and such..... this would be a good sign of the injectors causing the issue. As easy at it is to pull them, you might as well just get the washers and reseal them.



Man... . was kinda weird to see Justin Hohn asking questions... ... . :-laf

 

[ctd8999]

I had an injector hold-down that I failed to torque properly, this caused compession to go into the fuel tank. Just my . 02. Thanks Steve B.

 

[rkressg]

I am going to pull the Injectors this weekend and replace the washers. Hopefully this resolves the issue. I will post my results.

Everyone, thanks for all the help.
-Rich

 

[rkressg]

Just so this is in the archives, I have resolved the issue.

It turns out that Injector #4 was suffering from excessive blow-by. I had an extremely difficult time pulling this injector out of the head. There was an excessive amount of Carbon built up, locking the injector into the head. I actually had to use an Injector puller, the screwdriver and valve cover bolt method would not work (I was worried I was going to break something I was pulling so hard).

I pulled out the Injector, worked out the washer (which was locked to the head under a significant amount of carbon), and removed all the carbon buildup (which took about 1/2 hr to remove).

I replaced the washers on all 6 injectors. After putting the system back together, I was no longer suffering from a pressurizing fuel tank, and the white haze/smoke coming from the fill neck is gone.

-Rich