• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

MGB 77MGB gas tank vent

Share this page

kyreb1862

kyreb1862

Jedi Knight
Offline
How is the tank vent on a 77 MGB constructed? My vent is stopped up. I unscrewed the end in the trunk from the tank and tried to run a stiff piece of wire into the tank through the vent with no luck. Is there a screen or some sort of resistrictor over the end of the vent. I need to unclog this because it is pressurizing the tank. Any suggestions on how to clear this would be appreciated.

Regards John
 
No clue but someone does. Put a vented cap on meanwhile.
 
You may have a stopped up charcoal cannister up under the hood or the cannister in the rear fender might be stopped up.
 
tony barnhill said:
You may have a stopped up charcoal cannister up under the hood or the cannister in the rear fender might be stopped up.
Click to expand...

I rebuilt the cannister so I know its good and I can blow back through the cannister mounted inside the left rear fender but I can't force air through the vent that comes out of the tank. I unscrewed the fitting from the tank and it is clear but I can't blow air into the tank its self. I tried running a stiff wire down though the opening but it will only go so far and just stops. I'm thinking of shooting carb cleaner into the hole to see if it will soak through and open it up. If you have any more thoughts on this please let me know.

Regards John
 
Unless you need to vent that way for smogging, I think just using a vented gas cap is the way to go. I had a similar problem and the vented cap fixed it for me.

Guinn
 
You can get a piece of thin music wire or safety wire and clean it out that way too.
 
There might be a roll over valve or restictor to prevent fuel from getting into the vapor line. But I thought that was the function of the silver looking tin can on the right rear of the trunk.

Have you tried compressed air.. Just a little.

Venting the tank to atmosphere when you have a fully functioning carbon canister system is just plain silly. If you park you car in a garage there are benifits to such a system.

The rubber vent hose on mine cracked and I would get wiffs of fuel all the time while driving.
 
Ok, update on the stopped up gas tank vent, I have successfdully used an old hood release cable and a can of carb cleaner and opened up the vent. I sprayed in the carb cleaner and let it set for a day or so and then i really went aftyer it with the old piece of hood release cable and now I don't have a pressurized gas tank any more!

Regards John
 
And, and, and. The car runs great???????????
 
hmmmm... how is it to refill the car?
 
Nunyas said:
hmmmm... how is it to refill the car?
Click to expand...

No problem refilling the car but, now I am pulling the fumes from the tank and she is wanting to run rich. I'm going to have to go through thr whole carb adjustment thing again!

Regards John
 
Back
Top