JD 420 Cranks, won't start

[Westonium]

So yesterday I did some mowing, and pulling a wagon up the hill with some firewood, and on the last task & firewood trip I turned the key and just heard the starter motor whirring away, but not engaged whatsoever. It's a new battery, and the machine was running just fine moments before. I left it overnight, on a battery tender just in case, and tried again after work. Today I tested voltage at 12.3-ish. Turned the key, same sound. Starter motor spinning strong, but not cranking the engine. It was running just fine 10-15 minutes prior.

So, I had this brilliant-terrible idea! I had the side covers off, so maybe just hotwire it and see how it goes! Well instantly, no more whirring! The starter gear engaged, and it started cranking the engine - YAY! But... it doesn't fire. It will crank away, but no hint of sparking. You can see vaporized gas pumping out the exhaust as it cranks.

Any tips on what I fried with my attempt? My JD 4310 is sitting in the shop the last 2 weeks. I need SOMETHING to work. I can't afford to pay the shop to fix both - I already had an entirely different issue with a wayward screw going into the engine, that I just paid for about 10 days ago. Hopefully this is something I can order a part for and fix myself.

 

[Kish318420]

If it just cranks, then you now need to check for spark at the plugs. If no spark, check coil and condensor according to the TM1590 (Technical Manual) and/or CTM2 (Onan Engine Manual). If those check out then look at the points or the electronic ignition module.

 

[Richard001]

Hopefully, you didn't fry anything. It could be that when you hot wired it, there wasn't a path for voltage to get back to the ignition system, so it couldn't start.

It sounds a little like the starter problem might be something that was common with those vintage of machines. Read the following link and the other links that it refers to to get an understanding of what is happening.

https://www.tractorbynet.com/forums...problem-my-850-a-post2161177.html#post2161177

K7LN - That link goes to a problem with a diesel engine. I don't see how anything from that link will help this guys problem.

Richard

 

[Richard001]

So yesterday I did some mowing, and pulling a wagon up the hill with some firewood, and on the last task & firewood trip I turned the key and just heard the starter motor whirring away, but not engaged whatsoever. It's a new battery, and the machine was running just fine moments before. I left it overnight, on a battery tender just in case, and tried again after work. Today I tested voltage at 12.3-ish. Turned the key, same sound. Starter motor spinning strong, but not cranking the engine. It was running just fine 10-15 minutes prior.

Well you either have a poorly calibrated meter or your battery is not charged. See below:

A fully charged cell at 80 degrees F would show a specific gravity of 1.265. If all six cells are fully charged, an accurate digital voltmeter reading of battery voltage would show 12.68 volts.

Specific gravity for a 50 percent discharged cell would drop to 1.19 and battery voltage would fall to 12.24.

When specific gravity reaches 1.12, the cell is fully discharged and battery voltage falls to 11.89 volts, assuming the specific gravity is the same in all six cells.

Because specific gravity is affected by temperature, subtract .004 per 10 degree drop below 80 degrees F.

So, I had this brilliant-terrible idea! I had the side covers off, so maybe just hotwire it and see how it goes! Well instantly, no more whirring! The starter gear engaged, and it started cranking the engine - YAY! But... it doesn't fire. It will crank away, but no hint of sparking. You can see vaporized gas pumping out the exhaust as it cranks.

You don't say what battery you used to jumper to the starter. Was it the battery in the tractor or a different one?

Richard

 

[bruceatlam]

The key will need to be in the "Run" position for it to start.

 

[beenthere]

Also thinking battery is problem.


But also google "Starter Onan P220 engage issue" and learn more about the starter with some video's

 

[Westonium]

The battery was installed new in the shop 3 weeks ago. Just to convince myself it wasn't battery-related, I used heavy-gauge jumper cables to the larger marine-rv deep-cycle battery that's on my camper (also parked at barn) that is connected to a trickle-charger.

With and without the jumper cables, before I tried bridging the gap where the wire from the battery comes down and is attached to a nut, and the wire to the starter is attached. The solenoid worked, and the engine was cranking with no problem. I can test for spark tonight, but I will need a helper to do that I think (Not enough arms and hands)

As for voltage specifics - It was maybe 45 degrees out. I am not at all convinced that the battery is bad yet.

I will check out the Onan P220 engage issues via Google.

Also, I will get AM107421. My first goal is to just get the thing to fire up so I can drive it back up a hill and ~1000 feet of travel to where I keep the tools. Hard to find time to work on this. ****, I have to steal time just to post my questions here!

I appreciate the feedback. I will do my solid best to post whatever gets me sorted out.

 

[Richard001]

Keep in mind that most ignition systems don't like it when there is no discharge path thru the plug. So if you are going to test for spark, make sure that you have the spark plugs connected to the plug wires and that the body of the plug is grounded.

I use a large alligator clamp to connect to the plug and then a wire with a smaller alligator clamp on the other end. Clip that to the the engine some place. The use of the clamps prevents the plug from becoming dislodged from it's resting place as you crank the engine.

Richard

 

[Westonium]

Keep in mind that most ignition systems don't like it when there is no discharge path thru the plug. So if you are going to test for spark, make sure that you have the spark plugs connected to the plug wires and that the body of the plug is grounded.

I use a large alligator clamp to connect to the plug and then a wire with a smaller alligator clamp on the other end. Clip that to the the engine some place. The use of the clamps prevents the plug from becoming dislodged from it's resting place as you crank the engine.

Richard

Okay, the issue is temporarily resolved. I do need to replace the part referred above, but the engine fired up. I think that since I didn't have it set to "run" , I just super flooded the engine, and that if I had just turned it over a bit with the fuel off it would have started. I say this because it started up with no real change yesterday. The first few cycles weren't great but once it fired it was running the same as when I bought it.

I am going to try to show the machine some love this summer in terms of maintenance, upkeep, etc.

Thanks for the help everyone!

 

[Richard001]

Thanks for letting us know what the result was. Good luck.