Derek Vandivere wrote:
>
> -----Original Message-----
> From: Mark Dawson [mailto:torchbone@yahoo.com]
> Sent: Friday, 07 December, 2001 11:28
> To: dersk@usa.net
> Subject: Engine dies : 1978 MGB
>
> Hi there,
>
> Currently having a problem with the engine sputtering
> and dying while driving along - very inconvenient. So
> here's the setup: desmogged 78 B, Weber downdraft
> carb, new fuel pump, clean fuel filter, new K&N
> airfilter.
>
> Checked distributor cap, rotor, wires, plugs, all ok.
> Not sure how to check mixture on the Weber, but the
> plugs are not fouled and exhaust does not smell
> terrible. Checked the timing, it was advanced about
> 3/4 of an inch beyond timing marks. (?!) Adjusted it
> to 10 degrees BTDC, as per sticker under the bonnet.
> Idle set at 1000 RPM. This does not, however, affect
> the problem of dying.
>
> So what happens: the car will occasionally sputter and
> die while sitting at a light. This behaviour seems to
> get worse as the car warms up (coil? vapor lock?)
>
> If you push the gas pedal in when it starts to
> sputter, it will die completely. If you pump it a
> little it may catch and keep on running. If you keep
> it idling at ~1500-2000RPM it will continue running.
>
> If it dies, it acts like it's dieseling, then there is
> a terrible whirring sound coming from the Weber, then
> a puff of smoke as it dies. I'm not at all sure what
> would cause the whirring sound, but it doesn't sound
> pleasant.
>
> Any clues as to what to look for? Also, is there a
> good reason why a mechanic had set the timing so far
> advanced? (Note, changing the timing did not alter
> this behaviour one way or the other.)
I have had similar behavior with MGB, Victor MG-TF, Mini Cooper S
and Volvos.
In most cases, it was the electric fuel pump. When they get warm,
they fail more. The sound from the carby is from going lean & the
engine not firing: a roaring, sucking sound. Lean mix causes the
engine to backfire through the carb = puff of smoke.
Good way to test for this is to cut the ignition very briefly and
turn it back on quickly. This cycles the pump points and will
usually start it pumping again. Be very careful doing this while
running down the road if you have a steering lock.
"good reason why a mechanic had set the timing so far advanced?
Mechanic was a relative of "finger-tight Malcolm?" ;)
-Rock http://www.rocky-frisco.com
--
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