72 MFI idles but no power. Cycles between idle & 3000rpm

[72t4tom]

Any ideas as to what would cause this. I was driving, 3rd gear @ 5K and the engine stuttered. I drove several more miles and then I lost power. I pushed in the clutch & expected to see that the engine had stalled, but it was still running at idle. Raising the revs past 1400 & the engine cycles between idle & 3k, but no power. I can put it in gear & drive slowly at idle, but anything more & the engine balks

Thanks
Tom

[50/50]

Had a similar problem and went through a few shops with various diagnosis. The third shop figured out that it was the fuel
shutoff solenoid that was functioning sporadically. Found a replacement and problem solved.

[Flieger]

The cycling rpm sounds like the speed switch doing its job, but that means that the microswitch on the throttle crossbar is stuck in the closed position- that is, depressed. I haven't heard of that happening before but I suppose it is possible, or that there is a short. It also means that the speed switch is getting a signal that the engine is above 2500rpm or whatever the high cutoff speed is. If the engine is going above that then the signal to the rpm transducer is messed up. I think that comes from the wire going to the tach, though, and it sounds like that is working.

Have you checked the throttle linkage to make sure it isn't bent or broken anywhere?

[72t4tom]

Fuel pump rebuilt last year. tank removed & cleaned & new fuel lines & filter.

Microswitch snaps when pushed, but I will remove a wire. Linkage not touching switch

Checked under the dist cap. dry & clean

Where the RPM transducers & how do I check them?

???
Thanks for the help
Tom

[RSTarga]

As per the CMA:
Microswitch
a) Connect a hot wire to one terminal of the
microswitch.
b) Ground the other terminal with a test
lamp.
c) Turn on the ignition and actuate the
microswitch. When pressed down, the
test lamp must light. When released the
test lamp must go out.

RPM Transducer
a) Connect the test lamp with terminal 30 b
on the microswitch.
b) Start engine and slowly accelerate, at
approx. 1,500 rpm the test lamp must
light up.
c) Release the pedal, at approx, 1,300 rpm,
the test lamp must go out.

[72t4tom]

I went to start checking on your suggestions. I started the engine & it ran fine???. So I am still at a lose as to what happened. Thanks to everyone who helped! Maybe you chased it away with your mind powers

Tom