Sounds like you're right on top of it. If you have power at the plug and you tested the microswitch and it no longer hums.... (If it looks like a duck, quacks like a duck...) Mine was siezed from rust. I don't think they have a high failure rate but when the thing is 20+ years old... I'd replace the durn thing and eliminate the question. In the meantime if you REALLY don't want to do it, you can talk to Bill Robertson and he'll tell you how to "de-plumb" your engine. He knows how to get rid of all the computer junk and make the engine run well without it. I know I'll catch h&#) for even bringing it up. A lot of people disagree with his methods but I've seen his car and it runs well. I'm not doing it to mine but that's 'cause I'm a closet-historian. Rich "please don't flame me" Acuti ;) --- In dmcnews@xxxxxxxxxxxxxxx, "Jerry Harry" <jlharry@xxxx> wrote: > Well, My problem is not the vacuum its the idle speed motor. > Do these things have a failure history. Mine no longer hums when it should > or always did in the past and my idle no longer works at all. > When I start it up it will run if I give it some gas and keep it running > that way, if I let it drop back to idle it will just die, makes no attempt > to run. The idle switch is working and I have voltage on the motor plug but > the motor does not turn, nor have that little hum it had when all was > working. > John, Martin, David, what do I check next? Is it time for a new idle speed > motor? > Thanks for any input. > Jerry Harry > Vin# 4890 > PS: > John, your tank fix works great and was easy to install. Thanks again.