Christopher G. Moog writes:
> To get a backfire three things are necessary fuel, oxygen and ignition
> source. These occur several ways:
> running lean (doubtful from your description)
How, if the motor is running lean and burning all of the available fuel,
do you get fuel into the exhaust system? This is a genuine question;
one that I've been pondering for quite some time, as I've experienced
lean backfire before, and can't quite figure it out.
> You should check the gulp valve, if this is OK check for exhaust leaks
> and the ignition system. The gulp valve is the most likely cause. The
> valve is suppose to stop the outlet of the air pump from going to the
> exhaust when decelerating.
No, it's not. The gulp valve is designed to let fresh air, taken from
the air pump, into the intake manifold on very high vacuum conditions.
This is supposed to compensate for the S.U carburetters' natural
tendency to run rich under high manifold vacuum. The air pump still
dumps air into the exhaust under all conditions.
--
Todd Mullins
Todd.Mullins@nrlssc.navy.mil On the lovely Mississippi (USA) Coast
'74 MGB Tourer with air pump and gulp valve - in a box on the shelf!
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