> 1) What's a likely cause for the fuel pump's running on and on instead
> of running briefly and then shutting down when the bowls are full?
Is it successfully filling the bowls and running on, or is it
having trouble filling the bowls?
If you have an air leak in the fuel line from the pump to the tank,
the pump will have trouble filling the bowls and will pump for
a long time, half air and half fuel.
Similarily, as already mentioned, the check valve failure causes
a similar problem, the pump stroke pressurizes the line to
about 4psi, but then the pressure leaks through the check valve
and then the pump detects low pressure and fires again. It is
essentially pumping the same ounce of water over and over again
and leaking it back.
Another possibility is that your float valves have stuck open
and your fuel pump is either blowing fuel out your overflow valves
or filling your carbon canister, depending on your car set up.
> 2) What's a likely cause for irregular misfiring when *not* under load
> that smoothes out under full throttle.
Stuck distributor mechanical advance is often a cause of this. To
check, use a timing light and see if the timing advances when you
rev up the engine and then returns to its original place. Sometimes
it advances and then sticks there, so the timing is horribly wrong
except at high revs where it of course works where it's supposed
to be.
If that's the case, it takes 30 minutes to strip, clean, and
reassemble the distributor. That's my "pet job" actually, it's basically
free and helps so many cars even if their symptoms aren't drastic. The
distributor bits get coated with oil that gathers dust and makes
everything
sticky and fudgy.
--
Trevor Boicey, Ottawa, Canada.
tboicey@brit.ca, http://www.brit.ca/~tboicey/
[ Seeking some miscellaneous MG parts, see the list on the web page... ]
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