[mreilly]

Mornin'
1991 MTD LT12.5-38 [mod. 131-662F118]. This tractor cuts out while mowing as if the key was shut off momentarily then recovers in a couple seconds or so. Gets worse the longer you mow with it. Eventually just stops, but starts right back up usually. Replaced the ignition switch and have ruled out the fuel system. Mowed yesterday with a timing light hooked up [took MUCH longer to act up with the timing light hooked up]. But when it did cut out the timing light went dead so it is definitely is a "no spark" condition. Any ideas? Is there one common spot at the engine to easily disconnect all the safety interlocks at the same time to rule them out?
Many thanks guys,
Mike

 

[D-Dogg]

I think you are on the right track suspecting an interlock. Does it tend to occur when you bounce over something? Have a look at each of the switches and see if the plungers on any of them move freely or are sticky.

 

[LLigetfa]

Is there one common spot at the engine to easily disconnect all the safety interlocks at the same time to rule them out?

Don't know about the MTD in particular but in general the safety interlock all conspire to ground out the ignition coil. If you remove the grounding wire at the engine, it will disable the safety interlocks but it will also prevent you from shutting the engine off with the key.

Beyond that, forum rules forbid us from advising how to disable safety interlocks.

 

[walter g]

Reach down and clean the pto safety switch. Then push it in and out by hand 6 or 8 times. I have a 1991 669 and I had problems with mine. I hope you don't have to replace it, it's hard to get to the bolts.


Walter

 

[mreilly]

Thank you all for your quick replies and great info. I'll get back out there in a couple days and see what I can find. I'll let you know.
Thanks again,
Mike

 

[mreilly]

Hi all,
Just reporting back. Yes, it was an interlock problem. After disconnecting the coil ground wire, I could mow all day. I recalled doing a hurried "bypass" number out of frustration back in '92 when the tractor was a year old. I suspect one of my many splices loosened up somewhere. At any rate this decision was easy [a dash mounted kill button wired directly to the "you know what"].
Thank you. You've all been a great help.
I appreciate it.
Mike