• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)

Backfire on deceleration

Share this page

H

Harleyman

Freshman Member
Offline
Ok folks. Just bought 71 mgb and it backfires on deceleration . I've been told it's an exhaust leak somewhere. Any suggestions on where to look first or tips for finding the leak?
Thanks
Jim
 
One thing to check first- the "gulp valve" could be defective.
That is the big "gold" can on top of the manifold. First try disconnecting it from the right-angle fitting on the manifold, plug the hole and see what happens, odds are your car won't backfire now.
BillM
 
And welcome to the BCF, Jim! This is the place for excellent assistance and camaraderie with the obsession we all have for Little British Cars.

:cheers:
Mickey
 
I agree with Bill on the gulp valve vacuum leak, in which the valve could be bad, but it could extend to other areas. Check all vacuum hoses for cracks and loose connections. Make sure the carbs are not sucking air from the manifold gasket. A shot of WD40, with the engine running, at the connections will tell, (the engine will change pitch). Moss has the valves if needed. PJ

Vacuum leak possibilities,



 
Thanks Micky. The knowledge base is immeasurable on sites like this. I am an accountant who likes to tinker with these cars and I learn so much just browsing.
Jim
 
mgb 77 with su carbs backfires on acceleration both carbs any ideas fixed floats and new fuel pump so far
 
danbateman said:
mgb 77 with su carbs backfires on acceleration both carbs any ideas fixed floats and new fuel pump so far
Click to expand...

If it "backfires" in the carbs, you are running too lean.
 
Back
Top