MGB while driving engine cuts out if I let off or push more throttle it comes right back on

[BillyBob601]

1977 MGB engine cuts off while driving press gas or let off and engine returns to normal
any thoughts?

 

[bobhustead]

Not too much to go on from your description (does it happen at all RPMs, does it ever backfire). Although I was out of the trade (BMC line mech) in '73, so I haven't seen these cars, your car has a ridiculous smog system. Without expressing a firm opinion and just suggesting a place to look, the "gulp valve" has a big diaphragm with a small hole in it that is designed to make it move quickly when pressure differences are present in the chambers on either side of the diaphragm, which affects the amount of air going into the intake manifold. Maybe plug the hose from gulp to manifold and from air pump to check valve to see if the problem stops.
When Dr. Entropy shows up, he will probably have the answer.
Bob

 

[LarryK]

Check oil in carb damper, wires at coil for loose, fuel filter, heavy fob on keys.

 

[DrEntropy]

When Dr. Entropy shows up, he will probably have the answer.

Not sure if that's sarcasm or faith in my crystal ball.

With as lean as the description is, and the number of "extra" things that were hung on a '77 (and may or may not still be there), it's just as likely to be that gulp valve as the possibility of stale fuel having sat in the bowl, or failing Luminition system. Too many variables.

Did it run correctly last week? Or has it sat for months. Is there a fuel filter? When was it last changed. Does this happen when engine is at operating temp? Is the choke mechanism intact and working?

 

[BillyBob601]

Thanks will check those out.
there is no smog equipment on car when I bought it.

 

[Bob Branson]

My only experience with an engine cutting out as you describe was eventually traced to a condenser wire inside the distributor, that had insulation worn through and would short out against the point-carrier plate when the vacuum advance moved it to a particular spot. Never heard of it before or since, but it's easy to look.