Vacuum leak question - 2.9l

[JohnG]

I have been chasing a vacuum leak. While changing lines I noticed that there is vacuum line going from the charcoal canister to the gas tank. If the gasket that is supposed to be on the gas cap is gone would that cause a vacuum leak?

 

[Uncle Gump]

Those gas caps are vented... it's just more vented now. So I wouldn't think so.

 

[19Walt93]

Check the one way valve on the brake booster. I needed a grommet for the booster on the 86 I'm working on and I had to buy a kit with the valve included,I discovered the old valve was shot when I checked it. I had never seen one fail before.

 

[JohnG]

Thanks guys.

 

[mr_manny]

Tried out my smoke machine this morning.

Also found a vacuum leak at the charcoal canister.

Still going through my new-to-me bronco II, which seems to be running fine.
Should I be concerned?

 

[Cees Klumper]

I replaced my charcoal canister a few years ago with new, so perhaps they are still available.
I would be more concerned with vacuum leaks directly at the intake manifold or the throttle body (check underneath the thottle body, there are some vacuum line connections there).

 

[89longbed]

The line from the gas tank to the charcoal canister is just for venting the gas tank through the canister. It won't give you a vacumn leak. It can cause you to fail an E-Vap test for emissions if the system won't hold pressure when the tech pinches closed the hose at the canister. There's a short section of rubber hose (like at the canister) near the fuel filter that joins the two hard lines, and this can get old and not hold a good seal. The other hard line from the canister goes to the throttle body to draw fresh air into the canister and the gas fumes into the engine air intake. But that hose is on the outside side of the throttle plate so I don't think it could cause a vacumn leak.

 

[mr_manny]

I will be dropping the tank at some point in the future (Fill hose and Fuel gauge are having issues).
I'll make sure to check the condition of that hard line.
Thanks

 

[adventurousprime]

I have been chasing a vacuum leak. While changing lines I noticed that there is vacuum line going from the charcoal canister to the gas tank. If the gasket that is supposed to be on the gas cap is gone would that cause a vacuum leak?

That could cause you to fail a gas tank pressure test on a smog test, but shouldn't contribute to vacuum. I've been chasing down vac problems as well. Biggest help was changing the PCV/crankcase vent hoses, grommets, and valves. Also cruise control servo and transmission lines. The get cooked and cracked on the backside of the engine.