grinchsr 591 #1 Posted March 17, 2020 My 1987 418-8 (3118K801) stays running after I turn off the key. The switch #103991 was replaced a few months ago and was working fine until yesterday. I cleaned up the contacts at the motor connector but still the same problem. Another bad switch?? Share this post Link to post Share on other sites
953 nut 51,014 #2 Posted March 17, 2020 It could be the connector going to the engine needs to be cleaned up or the wire is broken. If the PTO is on and you get out of the seat will the engine keep running? Share this post Link to post Share on other sites
grinchsr 591 #3 Posted March 17, 2020 It is only used as a trailer hauler. Seat switch is long gone and have not even touched the PTO lever since I bought it. Share this post Link to post Share on other sites
gwest_ca-(File Mod) 10,441 #4 Posted March 17, 2020 Make sure the ground wire going to the side of the ignition switch is connected and in fact is a good ground. That is the one that should be shutting the magneto ignition OFF. Garry Share this post Link to post Share on other sites
stevebo-(Moderator) 8,034 #5 Posted March 17, 2020 Ray- Sounds like a mouse ate through some wires. I have an XI that will do the same for a short period of time then cut out Share this post Link to post Share on other sites
grinchsr 591 #6 Posted March 17, 2020 Thanks Hey Steve still want to buy it now? Share this post Link to post Share on other sites
grinchsr 591 #7 Posted March 17, 2020 I will try running a wire from the switch to the battery ground and see what happens Share this post Link to post Share on other sites
biged77 107 #8 Posted March 17, 2020 I was going to recommend what you already decided to do - run a wire from the switch to battery ground. The 418-8 and the other 1987 models do not have a separate wire to ground but instead assumes the switch is grounded through contact with the panel sheet metal. Using an ohmmeter I found on my 418-8 that the instrument panel was not grounded until I cleaned the contact surfaces and even the bolt contact surfaces to the adjacent sheet metal. Installing a separate ground wire is the thing to do. Ed Share this post Link to post Share on other sites
grinchsr 591 #9 Posted March 17, 2020 (edited) I just ran the wire to battery ground and it shut off with the key. Is this telling me to replace the switch? Garry you were dead on about the white wire Edited March 17, 2020 by grinchsr Share this post Link to post Share on other sites
gwest_ca-(File Mod) 10,441 #10 Posted March 17, 2020 There is nothing wrong with the switch. The problem is the original wire on the switch ground terminal is not grounded for some reason. Could be the wire to terminal connection at the switch is corroded or it could be at the other end of the wire. The diagram shows a ground to the chassis between the ignition switch and the seat switch which is circled. Could have failed there or fallen off. Garry Share this post Link to post Share on other sites
biged77 107 #11 Posted March 17, 2020 On my 418-8 there was no wire to ground. I believe the ground symbol indicates that the switch is grounded at the panel and through sheet metal to battery ground. But I've been wrong before, maybe the ground wire was just missing on my 418-8. Ed Share this post Link to post Share on other sites
wallfish 15,769 #12 Posted March 17, 2020 Use that test wire for battery ground to the switch body, not directly to the kill wire. That will verify the switch is good. My guess is the key switch body is loosing ground through the sheet metal connections. Clean up all of those areas to re establish ground to the dash panel or install a wire directly from the switch body to a better ground point Share this post Link to post Share on other sites
grinchsr 591 #13 Posted March 17, 2020 Hey Wallfish I just came in from running your test and you were correct. I grounded the switch body to the battery and it shut off. Thank you 1 Share this post Link to post Share on other sites