Uh-oh. Mf12 Not Starting!
Posted June 05, 2012 - 08:42 PM
With these issues in mind where should I begin to trouble shoot the ignition? I see that many have completed the SSI Coil modification but I'd like to start with some simpler fixes before I finally bite the bullet and tear down the tractor. I am an electrician by trade so I DO have meters and know how to operate them and the SSI fix shouldn't be too bad for me but I'd like to exercise any other options first, mostly because this is the worst possible time for this to happen as I'm swamped at work for the next few weeks and can't really dump hours into sitting in the garage tinkering.
In the meantime I'm going to read Ed Stollers webpages and see what I can get out of them as to my next move in getting enough spark to get me through the next couple weeks of mowing, until I get the chance to really get under the hood on a nice Saturday.
Thanks in advance for the help everyone, the tractor is a 1974 MF 12, with the H120. Which ignition type is on this model of engine in particular? I'm a total dork when it comes to fixing this tractor because until now I haven't had to really do much with it, it's been a garage queen for awhile.
Posted June 05, 2012 - 08:48 PM
Gonna go check your pics now................................
Ok, you said it was a 74 so it is probably electronic ignition. I'd check the pins and make sure they are free from rust and that the outside of the flywheel is clean also. I don't remember what the gap is supposed to be between the pins and the coil sensor. I'd also check the electrical connections there at the coil and make sure they are rust free. I think that is a ground wire on the spade terminal, so don't expect to find voltage, nor should you try to jump voltage to it, as that will certainly fry the coil sensor. Check and see if that ground wire is shorting to ground. Try a new plug, I've had them go bad.
Edited by HowardsMF155, June 05, 2012 - 08:56 PM.
Posted June 05, 2012 - 08:58 PM
First, find the wire that comes down from the ignition switch which would be a short to ground with the key off. This is your engine kill and you need to isolate and disconnect it from the system. Try to start the tractor. Be ready with a screwdriver to short out the spark plug to ground as the key will not shut it off. Hopefully this is what happens and you just need a new switch. Probably not.
Next is a little less pleasant, but for a guy who's probably felt voltage before, it won't be bad. Take your pinky and hold it to the frame, take the wire that you disconnected from the one that goes on over to the engine (not the switch end) and grip it or an extension wire with your thumb and finger and have someone turn the engine over. You should feel a slight tingle. Ed refers to this as the "tickle" test. You are feeling the pulse from the pickup that charges the CDI.
That's enough for a first step, let us know what you find.
Posted June 05, 2012 - 08:59 PM
Posted June 05, 2012 - 09:31 PM
Posted June 06, 2012 - 12:06 AM
If using Champion, it hould be J8 , which is now J8C.
Edited by IamSherwood, June 06, 2012 - 12:21 AM.
Posted June 06, 2012 - 06:11 PM
Sorry for the stream of questions, I'm just a little bummed out.
Posted June 06, 2012 - 08:01 PM
Useing a feeler gauge, you can check the gap. It should be between .006" and .010".
You adjust the gap, by moving the coil.
Posted June 06, 2012 - 10:53 PM