Odd thing happens when putting in gas at the station

[CJ7JEEP1979]

I have a 1979 CJ7 with a AMC 304 and 4 speed manual. Whenever I get gas, at any station in town and I put the nozzle in and start pumping, the trigger immediately clicks as if it is full. The only way I can pump gas is to barely squeeze the trigger which takes forever to fill up. I have never had this happen with any vehicle including a CJ7 I had years ago. I have pushed the nozzle in as far as it could go and I have pulled it out as far as I dare, nothing makes a difference. Anyone else have this problem and know what is going on?

 

[Scout1067]

Does it have a new fuel filler neck? I replaced my fuel tank a few months ago and the same thing happened until I put my old filler neck back. Just a thought.

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[JeeperChris]

Mine does it and i'm pretty sure all the parts are stock. I can usually find an angle that works but it takes some searching.

 

[Basod]

The newer pumps are sensitive to back pressure to prevent overfilling.
Check the vent line to charcoal canister isn’t blocked or collapsed (if equipped). Charcoal canister could be saturated or vapor pressure from hot engine back to canister is causing the tank to vent.


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[Lumpy Grits]

Turn the fill handle horizontal, and try that.
I've had to do that since day one with mine...
LG

 

[RiverandSand]

Turn the fill handle horizontal, and try that.
I've had to do that since day one with mine...
LG

X2 what LG said, angle the nozzle toward the fill hose into the tank.

 

[Steve Neul]

Mine does that on the rear main tank because the filler hose makes a bend too close to where the nozzle goes in. It causes gas to back up at the nozzle.

 

[GTOgoat]

The newer pumps are sensitive to back pressure to prevent overfilling.
Check the vent line to charcoal canister isn’t blocked or collapsed (if equipped). Charcoal canister could be saturated or vapor pressure from hot engine back to canister is causing the tank to vent.


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Check vent line for kinks, had this happen to my F550 work truck and BAM worked like a champ after!!!

 

[cglax6]

All good advice here. There's a pretty good bend in that filler hose, and pump handles these days are really sensitive to vapor and backflow. I have to turn mine ('76) just right to get a good angle. At most places, I'm able to lock the pump handle in on the first position.

It wouldn't hurt to check your vent lines up to the engine compartment if they're not capped off. If they are capped, it might do you some good to replace everything. Mine were capped off and I recently outfitted my vent system with a rollover/check valve, new lines, and charcoal canister. Not too spendy or hard of a job.

 

[CJ7JEEP1979]

Thank you for everyone's help! I greatly appreciate it and will try it out next time I get gas. I still have a lot of work to do to it before it can be my daily driver.

 

[Hurricane4]

All good suggestions here.

You probably have the 15 gallon tank unless someone swapped in a larger tank. I don't think a larger fuel tank was an option in '79 on the CJ models.

Maybe try to get fuel when the gas gauge reads between the quarter mark and half mark.