I just went ot put gas in my 82 XJ6. When I opened up the left side gas cap, gas just shot out like it was being pumped out. I am sure the pressure in the tank was causing this but why? I opened up the right side and it let out air but no gas (not sure there is any in the tank anyway).

So what is causing this?

Thanks

BOB

 

those stupid crossover valves, are stickin or leakin back

easy and cheap way, is get them out of system, and put simple TEEs in place , both inlet and return lines.

and only fill tanks to around 3/4 way full, it works out good.

and put two fuel filters in system, one from each tank feed(the 1/2" lines), leaky valves says rust is gettin into system.

 

Ok, where exactly are the crossover valves - I assume underneath the car between the tanks but you know what they say about assuming

 

The blow back from the tank is poor ventilation. Nothing to do with return or crossover valving.

Easy way to fix all of that....

 

In the right front wheel well you'll see the vent hoses going to the fuel vapor canister and probably also see two check valves. On the hose that runs fore-and-aft, disconnect the hose from the aft end of the check valve.

Report back if the problem goes away...or not.

Cheers
DD

 

Actually the problem went away before I did that. I went later to check it and it didn't do it this time. The car had been sitting in the sun in 100 degree weather when it happened. I later moved it to the shade and it didn't do it later so now I can't confirm anything other than it happened.

 

It will do it with heat. It should not do it at all. Something is wrong. When you are driving down the road it is happening you just do not know it & your tanks are imploding.
You need to fix it. Do what Doug said or you risk tank leakage & replacement.

 

Can I take out all the connections in the right front wheel well where the charcoal canister is and just leave the hoses hanging there? I took out the plat sic valves that were broken and don't have replacements so can I just leave the hoses not connected

 

Yes you can leave them disconnected, but I would advise installing a filter like a fuel filter or breather filter on the hose that used to attach to the plastic one way valve, since this is where air is breathed in for the tanks so they don't collapse due to lack of ventilation. If mud packs the end of the hose closed, there will be inadequate ventilation. So either use a filter or extend that hose and secure it somewhere where it won't get splashed. You don't really want water getting in there and freezing or affecting your gas.

Also, inside the filler necks there is a very small hole on the forward side. It needs to be clear in order for ventilation to work well. Stick a paper clip or pin in there and clear that hole.

By leaving them disconnected, your car will no longer be emissions compliant. The vented fumes from the gas tank will not be absorbed by the charcoal canister and vented into the engine to be burned. The car may also smell more like gas fumes.

Did you remove more than one plastic valve?

 

what would happen if i just connected both of the hose's together without a charcoal canister there...i am asking for trouble or would this just vent the fumes into the engine?