Diesel pouring out of filler tube when cap removed...

[karldavidson]

Over 2 months ago, I installed a 40 gallon auxiliary diesel tank in my Ford F250. Yesterday, I noticed diesel was leaking out under my truck. I checked all connections and none of them were leaking. I remove the cap from the filler tube and Diesel started pouring out.

The original tank is 2/3 full and the auxiliary tank is full. I have taken several trips with no problem.

The ambient temperature is averaging 95 degrees. I have no idea if this could contribute to the problem.

I took the filler cap off the auxiliary tank to see if it had built up pressure. But, it did no good. When I opened the filler tube cap, diesel continued to poor out.... In fact I would say it was gushing out.

Has anyone else experienced this problem? And if so, how did you solve it? Thanks, Karl Davidson

[fj12ryder]

If you can find where he says the original tank is "full to the brim" please point it out. Or are you assuming that's what he meant?

Uhh, I did read it, several times, which is why I asked the question. At one point he said the auxiliary tank was full, he took the cap off to see if there was a pressure build-up. Quote:

"But, it did no good. When I opened the filler tube cap, diesel continued to poor out.... In fact I would say it was gushing out." Now this was after he had taken the cap off the auxiliary tank to check for pressure build-up, so he appears to be talking about the main/OEM tank. However he says: "The original tank is 2/3 full and the auxiliary tank is full." Nowhere does he say the stock/OEM tank is full to the brim. In fact here is the first couple lines:

"Yesterday, I noticed diesel was leaking out under my truck. I checked all connections and none of them were leaking. I remove the cap from the filler tube and Diesel started pouring out.

The original tank is 2/3 full and the auxiliary tank is full. I have taken several trips with no problem."

According to that the original tank is 2/3 full and he has fuel pouring out.

[Grit_dog]

fj12ryder wrote:
So was the fuel coming out of the filler tank for the OEM tank, and that was only 2/3 full?

Uhhh no. If it was 2/3 full it wouldn’t be full to the brim. Re read.
OP, time to learn how to understand the fuel system in your truck. Did you at least shut off the aux tank and go burn some fuel out of the main?

[BarneyS]

Moved to Tow Vehicle forum from 5th Wheels.

[ol_Bombero-JC]

4huskers wrote:
You'll probably have better luck getting an answer in the Tow Vehicle section. I'd ask the moderator to move it there.

Luck will prob be about the same - but possibly more replies.

~

[fj12ryder]

So was the fuel coming out of the filler tank for the OEM tank, and that was only 2/3 full?

[Chiefcpo]

The instruction/user manual says to fill the main tank and then the aux tank. if the aux is full/overfilled it will leak. At least mine did till I read instructions, and do not fill to full, need room to expand. %0 Gallon is only 48 gallon when leaving room for expansion.

[Beaker]

I have a 40 gal Transfer Flow aux/fuel tank. This has happened twice,
however, I doubt more than a cupful came out. Was installed 8 years ago and never happened before. Original installer checked it and found nothing. Hasn't done it lately. Must add neither tank was near full.

[karldavidson]

Thanks everyone for your input. I have a gut feeling it is the check valve. Will keep you abreast of my search for a solution. Thanks again, Karl

[Dennis12]

You didn't rollcyour truck over did ya ?

[B_O__Plenty]

If you use the gravity fill kit that RDS sells, it includes a check valve that shuts off the fuel flow from the aux tank when your main tank is full. If you have this kit then the check valve may be stuck. Just shut the valve off at your aux tank until the fuel level in your main tank goes down.

B.O.

[Mbiviano]

What kind of aux tank? Have not had this happen before on my RDS gravity feed tank. If the factory tank is truly 2/3 full, not sure why it would flow out the filler neck and not down to the tank.

[path1]

Fluid seeks it's own level. If shut off is elec. Not working right. If manual, left open or not all the way shut. Be may guess.

[fj12ryder]

How do you have the auxiliary tank plumbed into the main tank?

If I've read this correctly diesel is coming out of the auxiliary tank when you take off the filler cap. If that's true then you've simply overfilled the tank and the increased ambient air temperature has caused the fuel to expand and the only place for it to go is out the fill cap.

[azdryheat]

If it is a gravity feed tank there is supposed to be an automatic fuel shutoff installed where the fuel line enters the main tank fill hose. If that isn't done correctly, fuel will continue to fill up the truck's main tank fill hose and drain out as stated.