Fuel Cut Solenoid

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Oct 12, 2005
Flatwater, NC
I have been diagnosing a rough idle condition on my new project 60 using the FSM. It wants to idle/run like %#&* below 1,200 rpm. I have all the vac lines in the right places, dizzy, plugs, carb rebuilt.

Just looking for more causes. I have noticed that the fuel cut solenoid on the deceleration system on the carb has two wires that run to the wiring connector. I found a third wire in kind of bad shape which had been taped up lower on the wiring to the harness by the PO. Is this supposed to be a ground? I think the emissions FSM shows a ground. If this wire is a ground, where was it grounded, the fender ?

This idle problem is driving me crazy...Hope I found something ?

Thanks for the help...
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This extra wire was not connected to anything...Just taped up. Where was the original ground position ?
Is the ground wire for your carburetor cooling fan attached to the manifold?
Do not see it/one. Where does it connect to the IM ? There is a wire taped up running along the wires for the fuel cut solenoid. Connected to nothing but tape.

Have not seen/noticed the cooling fan come on yet IIRC. Just looked at the harness and looks like the ground to both devices may be shared ?

The PO defnitely limped this thing along. The ps pump has the cooler bypassed, and the oil cooler has been bypassed (likely due to leaks in both). I have ordered the OEM oil cooler and an aftermarket PS cooler to take care of these.
I did a bunch of searching and could not find anything. So to answer the question, this must be a common ground in the fuel cut solenoid circuit then ?
I did a bunch of searching and could not find anything. So to answer the question, this must be a common ground in the fuel cut solenoid circuit then ?

There are only two wires to the FCS. The wires go through the ECU. The FCS is switched by the ECU by closing the ground.

What some people do, when they have a ground issue with the FCS is to just directly ground (i.e. bolt it to the block/frame, etc) the ground wire for the FCS. I don't recall which wire of the two is the ground.

I think you may be skinning up the wrong tree. You said it runs poor at speeds below 1200 rpm, that dosen't sound like the idle circuit is closed to me.

A lean condition would be my guess, if nothing else has been altered. The sources of lean condition are numerous, but vacuum leaks are prolly number 1, followed by shee-ite in the carb idle passages.

Have you tried spritzing carb cleaner into and around the carb at idle to see if you can obtain a smooth idle?

Also, if you have access to a gas analyzer, you will see the effects of a lean mixture in the exhaust gasses.

Please keep us informed of your discoveries and remedies.


i have the same idle issue and have literally five minutes ago found that wire you're talking about is the carb fan ground. without seeing pictures im sure we are looking at the same thing. mine was cut and taped because when i grounded it the carb fan ran continuously. that wire is not the source of your problems... in fact regrounding may only let you realize the carb fan wont switch.


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