MG4EVR@aol.com wrote:
> I have a 73 Midget, no pollution stuff, a very mild cam , electronic
> ignition, and a weber carb. Ever since moving to CO from MN I cannot make
>this car
> run. I have tried almost everything. It idles smooth at 1000 rpm but as soon
> as I put a load on it over 1500 RPM the tach starts jumping all over and the
> engine misses and struggles to gain power. Any ideas?
If there is a backfire through the carburetor when you try to rev it, it
may be a lean mix/ not getting enough fuel.
I tend to suspect high-voltage breakdown is the problem, though. This
might be a cracked rotor or distributor cap or a bad coil, but is more
likely to be a fault in the 12v+ going to the primary ignition circuit.
You might try to bypass the 12v+ supply to the coil by using a wire from
the battery positive to the positive terminal of the coil. If it runs
okay with that in place, check the ignition switch and all of the
connectors between the battery and switch and between the switch and the
coil. If the bypass wire doesn't help, run the engine at idle after dark
and see if you can see any arcing anywhere (like from the plug wires,
distributor, etc.).
One other common failure point is the wee braided ground wire in the
distributor, that grounds the rotary plate. This may or may not be the
problem, depending on the condition of the wire and what sort of
electronic ignition you have.
This symptom is sometimes caused by an oily dust and dirt coating on the
plug wires, plug porcelain or coil nose which allows moisture to build
up on these insulating surfaces and short them to ground, but this
usually only happens when the weather is cold and damp.
-Rock http://www.rocky-frisco.com
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