My fuel tank is spewing back at me

[merrill77]

So I've encountered two issues with my 77 Wagoneer when fueling:
1) I have to turn the pump handle to the right, 60-90 degrees from normal, to fill with any speed (I haven't tried to the left). Otherwise the filler clicks off.
2) When I get it full and the filler clicks off, I get a couple spews of gas back out the filler at 2-3 second intervals. The spillage is probably in the 8 oz range.

Possbily related - it also appears I can only put in about 8 gallons when the tank is reading 1/4. I realize that could be a problem with the sending unit or gauge...so I'm considering that as a separate problem for now.

I haven't seen this symptom discussed on the forums...but hoping that someone has a clue what is going on. I see a separate vent hole in the filler - is there a separate line for venting that might be clogged?

TIA!
Chris

[merrill77]

Sorry for the double-post. I got an SQL error from the phpBB software so I re-posted. Didn't realize it had worked.

[csuengr]

Sounds like a gas tank fill vent issue. Make sure the fill vent (smaller of the two hoses going to the back of the tank) is going up hill from the tank. Any low spots will accumulate gas and the vent will no longer vent.

[fulsizjeep]

77 was a bad year for fuel filler. I installed a fuel filler from an 81 in my wife's 77. This eliminated the rubber vent hoses in the cabin inside the LR fender and also allowed for better flow when filling. The CA and AZ fuel dispensers still give us hell though.

[Cheapthrills]

Might check also to see if the fill tube has fallen and created a belly under the vehicle I've seen this on many vehicles especially trucks with a utility box

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[merrill77]

Here are pics of (1) the inner fender filler line (2) underneath where the fuel line exits the fender and (3) the line as it snakes around the shock mount to the tank. This is not what I was expecting...I was expecting a separate vent line coming from the tank to allow air to exit the tank as you fill it. Instead, the vent line goes from the filler inlet to the fender well. So this vent line appears to be to allow air to enter/exit the tank when the cap is sealed...which makes sense, both to deal with expansion/contraction of the fuel due to temp changes as well as allowing air to enter as the pump pulls fuel from the tank. But it doesn't help to vent the tank during filling. At all. The vent line is crimped...I can't tell exactly how much when the panel is installed, but I do not feel like it is enough to prevent venting. And anyways, it's not related to my fuel filling problem.

In the 3rd pic, where the line snakes around the shock mount, it does dip a bit...nearly with width of the line. However, I'm not feeling remotely confident that this is a problem. I don't see why fuel blocking the inlet here would have any different effect at 1/4 tank than it would at near-full conditions. I'm guessing that the rubber hose with clamps did not come that way from the factory...indicating that this line was (partially) replaced at one point. There appears to be a part of a clamp that looked like it would have held the line in place near the shock mount. But it looks like it was cut and not replaced.

Maybe I _am_ filling the tank completely and either the gauge or the sending unit is off. Is the sending unit the same as an 87 GW? I have a new-in-box replacement. I suppose I should test the currently installed unit. And/or the gauge.

I should also try filling with the wagon parked facing downhill to see if anything is different. I know a place where I can do that...this should allow me to completely fill the tank and then I can see what the gauge is indicating.

[Cheapthrills]

I'm not familiar with 77 model year with some of the sudel differences like this.. but I would think the vent line should go to tank like the last 80s models to give tank a place for air to escape

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[merrill77]

Air can escape the tank by going back up the filler line, up to the inlet and out through the second line attached to the inlet that goes to the filler. That's the second line going off to the right in the 1st picture. I assume this is the OEM design (?).

[Cheapthrills]

Not saying it's not oem, but it doesn't look right... As that would allow gas fumes to enter the cab

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[merrill77]

Maybe I'm missing something? Or I've not described it well enough. The line that leads off the right (1st pic) appears to vent into the rear wheel well (outside of the car). I think it clamped to a fitting there that breathes out the top of the fender well...so it vents outside in the fender well above the tire.

[Cheapthrills]

Gotcha... that could also be why they changed it in the later years because of fueling issues... such as my 87 and 90 both are vented with a smaller line from tank to filler cap

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[merrill77]

Ahh - good to know that is what is on the newer models. That's what I was expecting to find. If that was indeed the reason for the change, then I guess I'd need to do the same to fix this issue. Hmmmph.

[Cheapthrills]

I do have the newer tank if your close enough to pick it up... and the associated filler neck.

I'm in Sedalia Colorado , it's yours if you want it.

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[fulsizjeep]

The rubber vent line here does feed through the fender on steel tube then underneath where more rubber line continues to the tank vent. This hose is a bit kinked in your picture. My wife's did the same thing. It restricts venting. One her's, the rubber line was also rotten at the time and vented into the cabin. The 81 filler neck and vent tube are steel tube that run down through the bottom side by side and toward the tank. Then there is rubber line from there to the tank vent. I don't have pictures because it was something I did many years ago.

[tgreese]

There is an excellent picture of the fuel tank plumbing in the TSM for every year AFAIK. Looking at the '77 TSM, the vent hos is supposed to go straight in to the filer hose near the top, using one of the bulkhead fittings used on many years of Jeeps. The vent hose does not normally bend. There should also be a rigid vent line in the middle of the vent line's course to the tank (which I don't see anywhere). Look here at figure 4-2. http://oljeep.com/edge_77_tsm.html That hose looks suspiciously like heater hose, which would be dangerously wrong for fuel. Look for markings on the hose. I suggest you remove your speaker and give us a better look at how those hoses connect.

[merrill77]

Thanks for that link! Bookmarked. My arrangement definitely does not match the TSM.

I'll get a better pic of the fuel inlet connections. And see if I can find anything attached to where the vent line is supposed to connect to the tank.