Back fire ?

[burt]

Hi yet again
Was out in the van today and the engine started to back fire it's happend before but today was the worst ever
It's seems to happen when I'm coming off the throttle more than when I accelerate
Do I need to just change plugs leads ect
Or could there be a bigger problem
Thanks in advance

 

[monkeyvanwestybike]

Air Leak on inlet ?

 

[StuF]

Recently had a similar issue on my bus coming back from SPA
Popping, banging and running poorly on load
Turned out that one of the Dizzy vac pipes had come off the RH carb and it was pulling too much air through the exposed port
Check all your pipes and as above check for an airleak around the manifolds

 

[TeamBrian]

Or a leak on the exhaust system. I had the same problem on deceleration and it turned out to be a leak on the 4 into 1 manifold....gummed it up and has never done it since.

 

[burt]

Thanks folks will take a look when I get home

 

[Earl Bay]

Could be (leaking) heat exchangers. I used to have massive backfiring, loud bangs when coming of the throttle at high rpm's And couldn't find the cause.
But when the exhaust fumes in the bus were undeniable even with open windows I decided to get new heat exchangers and the problem was gone.
But since you say you also have it when accelerating that's probably not it.

After the change I just had this nice brabbling and spitting noise going of the throttle, sounds like a 356 porsche I'm running a VS exhaust on a stock 1600 B engine.
Now it's getting a bit worse with a bit more popping and I have the feeling it's now running too rich (got the feeling the engine gets too hot too), because also I can't touch the dipstick even when it's only 26°C outside after driving in hilly terrain. And my bumper is a bit too black for my feeling.

So If this doesn't help you, maybe it'll help somebody else

 

[burt]

Right had it running yesterday and there is a lot of smoke cumming from the right exhaust pipe plus a blue flame when you Rev then take your foot off

 

[burt]

Ps I don't have any heat exchangers on at the moment
One of many jobs still to do
Thanks

 

[Bigbear]

I had a similar problem with backfiring, turned out to be the spark plug cap on number 1 had broken up and was giving irregular spark when warm or under load.