2nd Gen Non-Engine/Transmission fuel leaking out hose on filler neck

[JDKammin]

I am working on a guy's 94 2wd dually. It came in for a new oil pressure switch, thermostat and fuel gauge sender. He stated that when trying to fill tank completely up, he will leak fuel out under the truck. Upon pulling the fuel tank, I notice a small hose that goes from the top of the fuel module and tie strapped in a couple of spots along the filler neck hose. At the end of the hose is a plastic 90 degree vacuum fitting, which is about a foot down from the top of the filler neck. The plastic hose barb that the hose fits on top of the fuel module is on the opposite side of the plastic push lock hoses. This truck has a convertor, so I am thinking this may be a California truck and this hose could be emissions related. I am trying to figure out where this hose should be routed to prevent fuel from leaking. Any ideas would be appreciated. Thanks.

 

[charlessmith]

On my '96 and my '97, there is a tank vent line that connects to the front side of the fuel filler pipe, about 4" down from the outer cap. I don't know what it connects to on the tank.

When filling the tanks really full, I see air/bubbles coming out of this opening on the front side of the fuel filler pipe.

 

[GAmes]

By small do you mean 1/8th inch id or 1 inch id? The smaller one is a vent line. The larger one connects to the filler neck and activates the automatic shut off of a fuel nozzle.



12 valve cat converters are not limited to CA emissions, BTW. Mine had one, and IIRC they were installed on all 12 valves since '94.

 

[JDKammin]

I did a little research today, using my 94 service manual. The hose is attatched to the pressure relief/rollover protection valve. I can blow air from outside to inside, but not inside to outside the valve. So, the valve appears to be working correctly. I also found out the guy is trying to get every drop that he can, into the fuel tank and filler neck. I told him to stop filling the tank, when the auto nozzle quits. I am thinking since he is trying to fill it so full, he is creating excess pressure and is opening the pressure relief on the tank.

 

[LandShark]

I've also had leaks from the filler neck. The fix was to tighten the hose clamps in one case. The other time it took tightening the big clamping ring on the top of the tank.

I've never had leaks just from filling it all the way to the top of the fill hose.

 

[GAmes]

.

I've never had leaks just from filling it all the way to the top of the fill hose.

Me either.