Problem 1993 Holiday Rambler 34 Gas Tank Fill Issue

[Megaro76]

Hello
My new to me HR AlumaLite 34 class A 460 gasser on Ford F53 chassis has the issue I have heard of where the gas pump clicks off even at the slowest fill rate

After looking underneath and following the fill tube from fuel door on the driver side to the tank, it appears the fill tube is original with a noticeable dip before entering the gas tank. Does anyone know if this is correct? I’m going to take some pics to help show what I’m working with. Hoping to get resolved for upcoming trip
Thank you all in advance

 

[Kevin D Pem]

It's common,not normal. Get rid of the "P" trap and the fuel will flow.

 

[Megaro76]

See pics. Most of the fill tube is steel with I’m guessing some type of undercoating/sound insulation sprayed over it with the exception off the 8-10” shown with the hose clamps. @Kevin D Pem Thank you for your reply about getting rid of the p trap. I have tried pushing up and that section and it is pretty well fixed in place to the point I started to rip the screws holding the fill tube entry part behind the fuel door. So strange. I’m hoping some can offer tips to try in getting fuel flowing. I have not had much look at local rv services saying it just is what it is unless I want them to pull tank and make something custom.

 

[TEO]

Maybe it's just the picture but the tank vent line looks kinked, that could cause your issue if the pressure can't get out as you fill.

 

[T’sOVR&Explore]

Teo is exactly correct. That sharp fold in the smaller vent hose, visible just inside the back of the fuel door's location, is the defect. Eliminate that fold, so that the tank can vent air as the liquid enters the tank thru the big fill tube.

That small hose connects to the top of the tank, a connection which also has a short downward projecting tube inside the tank top, to stop the fill and create a slight residual air space, the "spit back tube".

This is proper design practice, so that the cool fuel in a service station's in-ground tank does not dribble on the ground at the customer's home in hot weather after filling up a very short distance before getting home. Thermal expansion as the fuel warms toward the ambient air temperature "grows" the volume in the vehicle tank, but you won't notice the expansion effect on a normally functioning tank fill/vent implementation because the residual space preserved by the spitback design is doing it's job.

In liquid fuel rocket work, that residual volume maintained for expansion at the top of tanks (In one G locations) is called "Ullage Space".

 

[Kevin D Pem]

Give us a measurement where your tape is and at the filler.

 

[Megaro76]

Thank you guys very much! I took another pic of the breather tube bend going into the fill tube near the fuel door. This angle shows it better. Still look pinched or is that normal bend for tight angle? I’m going to measure the other dimension next asked by @Kevin D Pem

 

[Megaro76]

I took three measurements to try and provide more details of what my gas tank fill tube is doing. All of these measurements are from the ground up. There is a p trap element going on but I’m not sure if it is typical from HR and/or the cause of my issue. Thanks for any info!!
Pic 1 Fuel Inlet
Pic 2Fuel pipe enters tank
Pic 3 Rigid fuel pipe lowest dip in between fuel inlet and where pipe enters gas tank

 

[Megaro76]

More info…. As I mentioned before, my initial thought was to just try and raise the low hanging section to get rid of p trap effect to get fuel flowing BUT it had nearly zero wiggle. Just now I thought if it loosened the three screws attaching the fuel tube opening to the fuel door compartment that might give some wiggle to pivot the opening while pushing up on the p trap area?? Well that gave me 3-4” of movement up on the p trap. I could also hear fuel trickling back into the fuel tank. So I’m wondering if I can find some way to strap up that section of the fill tube and then try refueling to see if that helps my issue with gas station pumps clicking off?

 

[T’sOVR&Explore]

My apologies, the better photo shows no kink up near the top of the spit back vent line.
Perhaps disconnect the vent hose at the hose clamped connection and blow thru it (connect a temporary hose to extend the reach to where you can blow thru) and make sure the vent path is not blocked.

 

[eZAK]

You can try wedging a piece of pvc pipe between the fill tube lip and pan.
If it works then move on to a more permanent solution, such as plumbing strapping material or something similar

 

[Kevin D Pem]

Let me regurgitate.

Your last picture showing fill and vent union is oriented properly?
Vent tube union is at what?31 inches just short of the filler door.

No kinks!

Piece are connected via hose. That makes things modifiable. Hoses can be shortened, right?

Your measurements indicate what? A three inch valley.

Silicone hose that is fuel safe I have purchased at napa.

In My opinion the p trap is your problem, and if you find someone that is not afraid of his job. The job is less than an hour to fix. That makes the job worth the effort even if you still fight filling up. At least you will be able to.

The vent can still be a problem, and this is why. If you over fill the tank, gas can fill the low spot in the vent tube removing the purpose it is designed for. Both of those hoses should have the valleys removed.

If I had a guess. Someone replaced a fuel pump, and did a bad job of it.