Slow Fuel Filling

Steve777 · **Joined:** Fri Oct 16, 2015 11:31 pm **Posts:** 279

This is a problem which has gradually been getting worse over say the last 6 months. Basically, when at a "gas station" if I try filling the tank at high flow rates, the fuel builds up in the neck and the pump shutoff kicks in. Wait a bit of time and the fuel goes down into the tank and then the cycle can repeat. At first I was fine leaving the nozzle on the first or second auto fill de-dent and it would work. But lately even the slowest auto fill setting is too fast. If I trickle the fuel in its OK. I am assuming this problem is due to either some blockage in the filler neck, or a plugged vent line to the tank.

I did take a look at the FSM, and the plumbing associated with the fuel tank, but I suspect those diagrams are for the gasser version (did they use the same tank and vapor capture system on the CRD?). The only small vent-like lines that I saw was one that comes up to the fill cap and one that comes part way up to the filler cap and appears to go a filter (sure would be nice is they labelled all these numbered things in their diagrams), that is if our diesels have them.

Since AFAIK no junk was made it into the fuel tank, it seems unlikely that there is something blocking the filler neck, but I suppose I could run a plastic hose down it a few times to clean it out. I also would have thought that with the cap off when you are filling the tank, the filler tube would provide a good enough vent at least until the tank got full enough to cover the inlet tube (I see this slow behavior even when the tank is < 1/2 full).

Did not see anything on this when I searched the forums. Lots on the rollover valve leaking but not this problem.

Thoughts on what might be going on here, and what is clogged?

GordnadoCRD · **Posted:** Fri Jan 11, 2019 7:42 am

Your vent is plugged.

I believe you will have to drop the tank to find/fix it properly. Wait until it's as empty as you dare without running completely out, or use a transfer pump (lift pump if you have one) to drain the tank before dropping.
IIRC all the vent stuff is in the rear driver side corner up on top.

SargeIndustries · **Posted:** Fri Jan 11, 2019 4:35 pm

Mine would not take fuel usually in the winter time. Once I dropped the tank and knocked the rollover valve out the problem went away.

Steve777 · **Joined:** Fri Oct 16, 2015 11:31 pm **Posts:** 279

Thanks Sarge and Gord.

Yeah, I was thinking that a non-functioning vent system was the most likely. Also was hoping that I could fix this without resorting to dropping the tank, but whatever (it will have to wait for better weather though).

Anyone try applying vacuum/pressure at the vent line on the side of the filler tube that goes back to that vent/rollover valve? Have not looked for it yet, but it seems that might be worth a try and could save some time in dropping the tank.

Steve777 · **Joined:** Fri Oct 16, 2015 11:31 pm **Posts:** 279

Finally had a warm dry day, so found that vent line that runs up by the fill tube, unclipped it, and took the plug out of the end. Then I tried blowing air into it with the "gas cap" off. No problem. Heard the air coming into the tank, it even got some fuel splashed out of the filler when I went too fast on the air (tank was still pretty full).

So the tube and vent valve does let air back into the tank just fine. Not necessarily the same thing as letting air out when you are filling the tank but I will see next time I have to fill it up. If not, then I will rig up some adapters to let me plug the miti-vac into then end of that vent tube and see it it can draw air out of the tank (when it is not very full).

Still hoping to get out of dropping the tank to fix this...

Slow Fuel Filling

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