Andy,
Oh no! Don't resort to the additives. Most of these will do nothing but
gum up the system and possibly mask any real problem.
If the car runs rough at idle, we can pretty well eliminate lack of
fuel. Dirty filters could still be a problem, and should be checked, but
are unlikely to be the only problem.
Some of the weirder problems that have bitten me in 20 years of TD
ownership that fit this description include:
1) Bad or failing condenser in the distributor - usually only
causes a problem between 3000 and 4000 rpm.
2) If you have an original air cleaner, check that the domed cover
isn't crushed down so as to cut off or reduce the amount of air being
drawn into the air manifold. Repeated tightening of the wing nut has
caused many an air filter to close down the already-small opening.
3) Bad gas is a definite possibility. I remember in 1993 being
visited by Harry and Dierdre Pyle who arrived with much the same
symptoms as you describe. They had gotten a bad tank full, but it was so
bad that there was mud settling out.
4) Make sure the fuel line from the tank to the fuel pump is clear.
This can suck up all kinds of crud from the tank. With an air hose, blow
air back into the line from the fuel pump end (before the fuel filter).
Then retest. If there is fuel in the filter, but no crud, this is
unlikely to be the problem. If, on the other hand, there is a dose of
water in the gas, a can of Heet should cure most of it. Otherwise, you
can drain the tank from the plug at the bottom of the tank, or by
siphoning.
5) Make sure the fuel tank cap vent is open and that the tank isn't
pulling a vacuum. But again, if it runs rough at idle, especially after
you just start it up, this is unlikely.
6) Make sure your distributor bushings are good and that there is
no wobble in the shaft. This could (and has on my car) caused an uneven
spark. A simple test with a dwell meter will turn up this problem
quickly. The dwell meter should give a rock-steady reading.
Those are just a few of the things I've seen. But my bet is on #1 or #2.
Regards,
Lew Palmer
-----Original Message-----
From: owner-mg-t@autox.team.net [mailto:owner-mg-t@autox.team.net] On
Behalf Of Dr. Moyce
Sent: Tuesday, December 04, 2001 2:59 PM
To: mg-t@autox.team.net
Subject: Still not running well
I've let cold weather, holidays and general discouragement move the TD
to
the back of the garage where it gets an occasional scowl as I walk by.
Readers may recall my recent odyssey into relplacing noisy tappets and
pushrods, which was followed (though maybe preceeded also) by
intermittent
bad performance. It always starts, but will run rough, and seems to
alternate between three and four cylinders firing under acceleration.
Since last posting we had isolated the ignition system, with widly
varying
resistance among the spark plug wires.
I replaced them, the rotor and the distributor cap, and reset the valves
to
.013 cold. Test drive was disappointing, with moments of restored
greatness, but mostly hesitation and mild sputtering. Lucas Sport coil,
Pertronix ignition and new plugs compete the ignition system, so it must
be
somewhere else.
Carbs performed normally in Colortune testing. Could I have gotten a
bad
tank of gas (water contamination or worse?) I've got a fuel filter in
the
system, which is clear. I'm getting desperate enough to start trying
fuel
additives.
Andy Moyce
52 TD
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