Steven C. Zabel wrote:
> I have no idea if the momentary engine failures are due to
> missing, to a clogged fuel line / dirty tank, or if it's all wrapped up
> into one big mess.
Here's a few odd little things that can cause similar symptoms, in case
one might help:
1) Broken wire in distributor. Little braided wire in most Lucas dizzys,
spotwelded to rotary plate or base-plate. The spotweld can let go or the
wire break, generally causing spotty ignition and unpredictable
misfiring. Check all the other connections and make sure they aren't
hanging by a few strands of wire.
2) Bad fuelpump or rotted fuel hoses. You can usually feel that rotting
hoses are bad just by squeezing them. They will either be rock-hard or
squungy. Rock-hard hoses are ready to split, so should be replaced;
soft, spongy hoses may clog themselves with frayed bits inside even if
they look good on the outside. A fuelpump can continue to work in some
circumstances but deliver less fuel than what's needed. This will cause
a lean mix and might harm the engine if you get P.O.d and continue to
floor it.
3) Slightly too-rich mixture, caused by bad float needle-valve or too
high fuel-pump pressure. This can effectively limit the acceleration of
the engine to a certain rpm, where it starts to get rough. If this is
the case, petrol will be running out of the top of the guilty carb's
floatbowl. SU floats don't need more than a pound or so of pressure.
They require a good flow, but not at high pressure. If you're using an
aftermarket pump like a Facet, etc. you might need an inline
fuel-pressure regulator. Most hot-rod and speed shops sell them for
about US$15. Best set at around 1.5 pounds.
4) Bad coil or coil-related connection. The higher the load, the more
hi-voltage needed at the plugs to fire the mix. Some bad coils will idle
an engine, but stumble as soon as you try to drive it. Others will run
fine if driven by a little old lady, but stumble the first time you
floor it. If the power fails under-load only, this is an area to check.
A bad connection anywhere between the battery and the coil can produce
these same intermittant symptoms, whether it's in the ignition switch or
a terminal somewhere. Bad high-voltage components can cause similar
problems, diz cap, plug wires, even oil-and-dust-dirty porcelain on
plugs in humid weather.
-Rock
--
Rocky, JJ Cale Band & Pratchett Books: http://www.rocky-frisco.com
Rocky's Mini Cooper Page: http://www.geocities.com/MotorCity/6437/
Mini Books: http://www.geocities.com/MotorCity/6437/rockboox.html
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