[chuck_titcomb]

Hi all, I was recently given my dad's old 318, which he bought new in '86. A green family heirloom if you will... Before mom gave it to me she had her local small engine guy rebuild the bottom end so it would run good. He put new rings in and new gaskets.

It ran for a 3 hour mowing at her place before I took it home, but did surge at times. Also when I stopped mowing part way through and went to restart it wouldn't. It wouldn't even crank. I guess time and cooling down helped because we eventually got it going.

Since I got it home I mowed once and it died while mowing a level part of the lawn. It cranks but won't run. I had to push it back to the garage, not fun!

I have downloaded the TM from the site here, thank you! I've run through a bunch of the troubleshooting but wanted a second opinion:

318, P218G-I, s/n 425694

No spark unless I use a jumper from the battery to the positive terminal on the coil. I get no power during cranking to the positive side of the coil. The manual tells me that the wire or connector is bad but I've checked for short to ground and continuity and that wire's fine. I've even back probed the TDCM connector and ran a wire to the positive terminal on the coil and still nothing. I don't think I'm getting power to that pink wire at all. Which leads me to think the TDCM is toast. Is there a way to test it? When I jumpered from the battery to the coil positive terminal the TDCM started ticking and I got spark while cranking. The coil is out of spec (16.8 k ohms) but I'm trying to fix one problem at a time right now.

I'm sorry for the novel, but I'm at the end of my rope on this one and wanted to include as much info initially as I could think of.

 

[jdgreen]

Charles,
It sounds like it could be a safety switch that is not working properly. That said, it could be one of many on the tractor. Check them all (including the seat switch). It may also be a bad ground wire or the circuit breaker located under the battery tray. There is no magic bullet for this type of problem, only trial and error.
Good Luck

 

[Hammerdown-7]

Hello Charles
Welcome to the forum, member's here are very helpful. The wiring harness in these older 318's sometimes have connection issues due to their age, vibration or simply slight corrosion issues. Since the engine has been pulled recently for a lower end rebuild it tells me that the wiring harness has been disturbed which may mean a broken wire or bad electrical connection somewhere. In the past I have used di-electric grease on all of the connector's on my 1983 John Deere 318 as well as my son in law's 1991 John Deere 316 that has an Onan P-218 in it. The use of di-electric grease help's the connector's make a better solid Electrical connection. The wiring system in a 318 or a 316 has to have the Power travel twice through it before the machine can start or run as it all has to go through the TDCM which is the Brain of the electrical system in these Tractor's and all of the safety switch's have to be working correctly to allow it to start or run properly. I would start Looking closely at all of the Harness connection's and safety switch's to make sure they have Good solid connections. The Later made 318's like yours have a Ground wire that run's directly to the battery, so check that to make sure it is Grounding correctly. I would also look closely at the Fuses of the machine the later one's like your's have the large flat spade style fuses and in the case of my son in laws later made 1991 John Deere 316 I found one of the fuses not making a good contact so I had to squeeze down the female end in the connector to provide more pressure on the fuse and that fixed the no Power issue to the Tractor. Please let us know what you find we will help if we can. Regards, Kurt

 

[ryan214]

I would check the connections going into the ignition switch. My 214 would shut off and sometimes wouldn't crank or would crank but wouldn't start. The wires going to the ignition switch were loose and all I have to do is jiggle them and it will start. I also found out that the starter and coil are on separate wires hence the cranking but no spark. I don't know if the 200 and 300 series are that close but it can't hurt to look. Good luck.

 

[chuck_titcomb]

Thanks for the ideas guys! I'll start looking at the safety switches and the ignition and let you know what I find. Kurt this actually has the glass cylindrical fuses, and they are both fine.

 

[craft57]

Chuck : ….. just another thought tho ??? ….. did you check the glass fuse with a continuity tester ??? ….. Glass Fuses have been known to crack off inside the base of the end cap ….. There's no way to visually see that …… If you had done that check with a tester ….. Please ignore this Post ….. lol …. Good-luck !

 

[threeeighteen]

I'd replace the coil FIRST. Get one from "Boomer"

 

[chuck_titcomb]

Gary, I did check it and it has continuity.

Steven, I'd like to replace it, but money's tight right now and when it gets power it still works, so I'd prefer to focus on the root cause right now.

I was running through some of the troubleshooting steps this weekend and it had me checking for voltage at connections on the TDCM connector. While moving the connector around I heard ticking from the TDCM, current! So I disconnected the connector and cleaned it out real well and used dielectric grease on the connector. It started and ran pretty well yesterday afternoon (intermittent use, picking up piles of sticks and stuff with the trailer, minimal mowing), but then died again on me. I tried moving the cable connector around again and could not get the TDCM to tick unless I used a jumper from the battery to the positive terminal on the coil. The next step in the troubleshooting says to replace the TDCM. I may pull it out and pop the cover and look for anything obviously wrong, like a fried resistor or broken solder joint.

 

[jlang]

I have a similar problem I've been working on for my 316 plow day tractor. Got it to start 3 or 4 times this week but will not keep running.

This spark tester lights up when the tractor runs.

 

[Mills]

is the TDCM supposed to "click" when the key is in the run position and motor not running?

 

[chuckv]

yes...if the seat is not occupied and the ground speed lever is not in Neutral/Stop. That is the ignition kill relay opening up. If the parking brake is set, the lever in Neutral/Stop and all PTO switches are off, then just as the key is turned on that same relay pulls in. Here is the wiring excerpt that shows some of the logical internals of the TDCM (highly simplified over the actual components involved...)

Chuck

 

[Mills]

thanks Chuck. I believe mine is working correctly. however my coil has an open circuit on the secondary side. looks like it is time for a new coil.

 

[bloodrunsgreen]

Just a reminder that John Deere wants the coil moved from the holes in the tin to back on the cowl which I think would interfere with the governor linkage so I put mine on the firewall on one side leaving room for a fuel pump if needed later. Plus cover the holes when moved , also I lengthened the coil supply wires and got different spark plug wires.

The new coils are heat and vibration sensitive I guess, have one sitting here that cracked and ruptured in less than a year.

Also get a new condenser