[Mgs] Gulp valve: how would I know that it has failed?

[PaulHunt73]

Backfiring occurs because when you shut the throttle on the overrun the 
mixture becomes rich.  Normally not much of a problem, but with the exhaust 
air injection the rich mixture (without a gulp valve) combusts in the 
exhaust.

Certainly when open the gulp valve does inject air into the inlet.  Normally 
this is only when the throttle is closed i.e. high manifold vacuum.  If it 
were stuck open all the time I think you would know about it from very poor 
running, even if you had maladjusted the mixture in an attempt to compensate 
for it.

Normally they stick closed, and cause backfiring.

PaulH.

----- Original Message ----- 

>I was wondering if there is a failure mode in which the gulp valve
> always allows air through, so making the engine run lean all the time.
>