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Discussion Starter #1
Team JD,

Happy Father's Day!

The 1990 316 has been running better that she has in years. The new carb this winter definitely made a HUGE difference.

I was cutting grass yesterday and she started miss. I moved it over to the shed where I was going to check to see if it was low on gas, even though I gassed it up before I got started. I idled it down and it shut off. Now, I cannot get it to crank at all. The light on the dash goes out when I turn the key. The ignition switch has been on my list to replace for a while. The switch has had a "spot" where it would make contact and fire off. Otherwise, it had a dead spot, so I know the switch is on its last leg. Also, the starter has been finicky on occasion, like I was looking at a replacement starter project. After letting it cool down, it still would not crank over at all.

I believe that I have a problem in the electrical system, but I don't know where to start trouble shooting. I cannot imagine that a bad ignition switch or starter would cause it to miss and then cut off all together. Now, it is a lovely 28 year old lawn ornament. :(

About 5 years ago I had the stator replaced behind the flywheel. Pulling the engine was beyond my abilities.

Where should I start?

Thanks!
Chesapeake Bob
 

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Bob, Check battery voltage first. Then check for 12+ volts at solenoid, key "on", then key "start". I'm thinking probably the ignition switch. A bad stater shouldn't make it miss but a low battery of poor contact in switch will! Bob
 

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You may have a couple of different issues going on at the same time. Your description of the ignition switch problem sounds more like a starter solenoid issue than the switch. My experience with faulty switches is that they don't end up with a "sweet spot", but you can check that out with a multimeter at the switch or a jumper at the solenoid - the jumper essentially bypasses the solenoid by connecting one big solenoid lug to the other (use a #6 or better wire for this, a screwdriver works too if you don't short it to ground). Through it's life, a solenoid gets more and more of a burn on the high amp switch, eventually leading to a spotty starter rotation condition.

The other issue you described was the shutdown and your inability to re-start. The P218 has a known problem with the solid state ignition where the timing ring or ignition module fails and needs to be replaced (they recommend changing these as a set). If you're still unable to restart the engine, check for a spark (the technique is described on this site as well as elsewhere on the internet - the P218 has a Wasted Spark Ignition System where both plugs fire at the same time). If you have a spark but no start, your problem is elsewhere. With no spark and no start, I'd go to onanparts.com for a replacement kit - he has the least expensive parts I've been able to find.
 

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I forgot to mention that if your tractor restarts and then shuts down again later on, the module may be overheating - check the belly screen under the tractor to see how plugged it may be. Often the entire cooling path needs to be cleaned to clear up this condition.
 

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Discussion Starter #5
Bob, Pete, Thanks for working with me on Father's Day! LOL.

I have 12+ volts at the battery. With someone sitting on the seat, with the key turned to "on," I have almost no voltage at the starter. I tested it with a multimeter on the lug with red cable coming from the battery. When the ignition switch is turned to "start," I have 12+ volts at the lug....but it does not crank. I believe that I am testing the voltage at the correct location on the starter solenoid. What do you think? Ignition switch or starter or both? I am thinking it is a bad ignition switch on the dash. If everyone agrees, my next puzzle is how do I get to the back of the switch to replace it?

Any and all comments and suggestions are welcome!

Thanks!

Happy Father's Day!
Chesapeake Bob
 

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You need to check the voltage on the small wire (purple wire on the solenoid spade connector). That is what pulls and completes the circuit for the starter.
 

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Your checks are generally OK, but not far enough. The positive 12 volt reading should be available at the starter lug that has the heavy wire from the battery at all times (except for when your battery is disconnected) This is one end of the high amp switch. The other lug on the starter solenoid that looks like it has a wire going from it and into the starter - this is the other end of the high amp switch and when this switch is closed, the battery power can now turn the starter motor. To bypass this switch (solenoid), you use a jumper to connect these two lugs, however if you just want to check with a multimeter, see if you have 12 volts at this second lug when you turn the ignition switch to start. I you do, the solenoid switch has closed and is doing what it's supposed to and the problem is in the starter. If you don't get the 12 volts with the ignition switch turned to START, you have a solenoid problem (assuming the thinner purple wire is plugged into the connector on the solenoid.
 

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I will continue to trouble shoot this tomorrow after work. Any suggestions how to get my multi tester probes or alligator clips back to solenoid? It's tight back in there and it is all I can do just to reach the lug with the red battery cable.
 

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I will continue to trouble shoot this tomorrow after work. Any suggestions how to get my multi tester probes or alligator clips back to solenoid? It's tight back in there and it is all I can do just to reach the lug with the red battery cable.
Yes that will be tough without lifting the engine and I can't remember if you can see both lugs from underneath, but with that style starter/solenoid configuration, if you know that 12 volts is getting to the solenoid, you now need to check the low amperage side of the solenoid - that's the thin purple wire that is the positive side of the high amp switch engagement coil. When the ignition switch is in the START position, you should read approximately +12 on that wire and it's pushed onto the solenoid with a spade connector, just pull it off and test the voltage, you can put it back with a set of long needlenose pliers. If you do get the +12 showing, you know that the inputs to the starter/solenoid unit are good and the unit needs to be removed for replacement or repair (a starter/alternator rebuild shop should be able to help you), If you want to go further once the unit is removed, you can connect the second lug to +12 and the starter case to ground and the starter should run if it's working - this would narrow the fault to the solenoid.
 

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Discussion Starter #10
I am beginning to think that in addition to possibly needing to change my starter, I am going to need to replace the ignition switch as well. The switch has been acting up for a while. This I believe is in addition to the starter issue. How in the devil do I get back behind the ignition switch (on the dash) to disconnect it, remove the old and replace with the new? I took off the side panel but there was no way I was going to be able access the back of the switch.

Thanks!

Chesapeake Bob
 

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Pull out battery and battery pan, then unscrew nut holding key switch (on front of pedestal) then grab the harness and plug, wiggle and push switch back out out hole, retrieve the whole thing with it still plugged into connector(s). Clean inspect for damage connector(s) (heat damage from high current flow). Clean the connector(s) and put dielectric grease on new switch tabs, put new switch back on connector(s) then feed the whole assembly back into the hole.
 

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Discussion Starter #12
The problem was found! I spent at least an hour and a half last evening looking for the problem as to why my 316 would not crank. The headlights would come on and the dash lights would as well. That was it. A couple of years back, I put a Facet electric fuel pump on. The see-through fuel filter was dry. Even the fuel pump was not getting juice! I looked for an easy way to test the voltage on the back of the ignition switch. I was stumped so I went on and checked the fuses by removing them and checking for continuity. The fuses checked out OK. I was then going to check the small wire on the starter solenoid. My leads were not going to stretch so I decided to make a jumper cable for the black ground wire of the multi tester. I went to attach the alligator clip onto the lifting ring on the port side (right hand side for any non boaters). The lifting ring was loose. "Hmmm! Well, that's OK because I am NOT pulling the engine out tonight anyway." Then I clipped to the black lug that attaches under the lifting ring. That was loose too. That one bolt that attaches to the engine block was the ground wire for the negative black battery cable and the fuel pump. I jiggled the wire and the fuel pump kicked in! The loose ground at the engine was the culprit.


Thank you everyone for helping me to trouble shoot this one! At some point I will need to replace the ignition switch and the starter, but I'll burn that bridge when I come to it. Thanks guys!

Chesapeake Bob
 

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Check the threads on the lifting ring bolt holes, I've noticed on a couple of Onan engines that the threads are all but gone needing to be fixed with a heli-coil or retapped for a larger size bolt. I'd suspect that between the engine vibration, bolt removal for things like fin cleaning etc., and the "natural" over-tightening of a steel bolt in an aluminum head eventually stresses these threads to the point of stripping. I've changed my attachment point for the ground on my 318s - I've added a longer ground cable from the battery with a heavy duty 4 gauge lug and attached this to one of the front engine mounting bolts. This way it all comes apart whenever I need to remove the engine without any extra stress on the engine.
 
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