Hey, y'all, quick question.

I recently acquired a 1978 F250 Camper Special, 400 CID, twin tanks, and am having to fix a few things on it. Well, quite a few things on it, actually.

The rear filler hose is disconnected at the filler pipe up top, that explains why the fuel I added went onto the ground. No prob.

The mid tank filler hose is connected, but the vent hose is not. It's disconnected right where it would connect to the filler pipe (near the gas cap) but when I add fuel to that tank, it takes some in, then some gas comes out of the vent line! What would cause that, and would simply reconnecting it prevent that?

Is there some mechanical voodoo going on with the filler neck that prevents gas from escaping through the vent line? BTW, the tank is almost empty. Thanks in advance, this truck needs TLC and I'm new to all of this.

 

Either an obstruction in the tank, or collapsed filler hose. In my experience, for the rear tank at least, the hose has an easier time if it's flattened out somewhat. New hose sets have a C-clamp for this purpose. No idea why and how that translates to a midship tank, if at all.

Nope.

 

If your vent hoses are disconnected, the first things to do would be reconnect them, otherwise you're pretty much guaranteeing a fuel spill while filling and driving.

Once reconnected, you'll either have no more leaking, or will identify further hose issues, as I found with my own Camper Special. Both filler and vent lines on rear tank were so rotted they just ripped right off without undoing the clamps.

If you find you have filling problems after reconnecting the vents, then it's highly possible you have a collapsed filler or obstruction as FMC pointed out, but IMHO you gotta stop the spills first.

Both rear and side tank filler hoses have a C-shaped metal clamp dealio to flatten the hose between the frame rail and bed. See LMC catalog page (side tank shown, rear tank similar) Truck Parts and Truck Accessories

For reference, bulk fuel hose can be used, at least for the rear tank (I haven't done the front yet). Sizes are 2 1/4" dia. for fillers and 3/4" dia. for vents. At rear tank both are 15" long.

Also, be aware that the tanks must be dropped (or bed lifted off) to access the hoses.

 

Many thanks. Is fuel line measured ID or OD? I would guess it's OD since I read in another thread that someone was using furniture foot caps to cap off their fuel filler lines and said that three-quarter fit the vent line so that must be OD.

Hmm...bed or tank? Which is easier? Driveway sloped, thinking tank drop may be. Off to research more threads!

 

Totally embarrassed! In my haste, in the rain, I didn't have the gas can nozzle far enough into the filler neck. Added gas today, not a drop spilled. Still need to connect vent hose to neck, but it's too short by an inch so either patch with a larger piece of hose and clamps, or replace entire unit? Since it's only a vent, first option seems ok?

 

Since no-one answered your previous post (sorry, been busy tackling issues on my Jag), the pipe diameters are inside. Just order the sizes as quoted and you'll get the right size. Filler Neck Supply Co. sent me the required hoses for $30 total.

If the vent line isn't connected to the filler neck I'd say you're still risking leaking fuel when the tank is full, especially on right-hand turns. I suppose you could hand-knit a repair to connect it, but I'd question the overall condition of your filler and vent lines, and there no way to get at the tank-side connections with the tank in place.

If you haven't done it yet, my opinion is that dropping the tank is easiest, as it's a one-man job whereas lifting the bed will need either several sturdy friends (that will need paid off with pizza n beer later) ir some kind of lifting equipment. Use ratchet straps to lift it back into place, I can give you detailed description if you need it.