Ignition coil drops to 0 volts when starter engages ???

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BishopsBowyer
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Joined: Sun Dec 19, 2021 12:59 pm
Zip Code: 75765

Ignition coil drops to 0 volts when starter engages ???

Postby BishopsBowyer » Sun Dec 19, 2021 1:47 pm

Hello,
I am new to this site. I recently purchased a 1974 Lo Boy 154. I need it for hauling wood for our home heating and to rig up a plow for trenching. I did some swapping for it cause funds are tight with my wife and I both being disabled. (Just a note -- I am not a lazy man, I was forced into disability by the rulers that be. But my wife has been disabled since we were picked up and tossed around by an F4 tornado.)
The previous owner sold it because it was so hard to start. It looks like they re-wired the entire tractor. They did not replace the ignition switch, but the starter solenoid looks new. They removed the sediment bulb and ran the fuel line directly to the carb.

It is extremely hard to start. I can try starting it 100 times without so much as a sputter, then suddenly it starts right up.

I installed an inline fuel filter and rebuilt the Zenith carb. I also upgraded the distributor to 'electronic ignition' and put a new ignition coil from Hamiltonbobs. After that it fired right up. I started it for 4 days in a row, started each time within 3 or 4 tries. I wasn't going to put it to work until I changed that nasty black oil thats in it so I had to wait 3 weeks to get money for oil and filter. Then I went to start it to warm up the oil for draining, but it wouldn't even sputter - even with starting fluid. It was dripping gas from the carb so I immediately thought (incorrectly) that it was flooding every time I tried to start it. So I pulled the carb and checked the float adjustment which is at specs (1 5/32").
I then pulled the plugs and cleaned and re-gapped them (.023") , they were fowled black with carbon. Stilkl no start. I then checked for spark, but no spark (grabbing the top of a plug without a rubber boot - NO SHOC. I've always checked for voltage from the distributor that way. Then one time I did get a shock and the tractor fired right up, ran for 5 seconds and died like I shut the key off. I get voltage to the + side of coil when the key is in the on position, but the voltage drops to 0 when I turn the key to the start position.

Does anyone out there have the wiring diagram, specifically the ignition system wiring diagram? I have one I found on line, but it is bad quality and some things are just blank.

When it runs - I love it.
Thanks for your time
God bless.

BishopsBowyer
Posts: 3
Joined: Sun Dec 19, 2021 12:59 pm
Zip Code: 75765

Re: Ignition coil drops to 0 volts when starter engages ???

Postby BishopsBowyer » Sun Dec 19, 2021 6:39 pm

Update: I found a wiring diagram online and after studying it a bit, I found that I could run a jumper wire directly from the battery positive to the ignition coil positive , temporarily of course, while starting. So I did. She started right up. I guess I just need a new starter switch????

I know I need to do a little (or a lot) of clutch work cause she likes to grind. Also I need to troubleshoot why the hydraulics aren't working.
I will try to stay up to date with this site.
I also found a 64 Cub for sale, just wish they would barter for the $1000.
Thanks and God bless.

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Dale Finch
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Tractors Owned: '51 Cub #140966 "Bruno" with Woods 59 mower
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Re: Ignition coil drops to 0 volts when starter engages ???

Postby Dale Finch » Sun Dec 19, 2021 7:20 pm

Hydraulics...first check the fluid level up to the fill plug (with arms in rear/piston retracted position). If they aren't there, just leave the fill plug out when testing, to keep from over pressurizing, allowing excess to run out.
Dale Finch
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Eugene
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Re: Ignition coil drops to 0 volts when starter engages ???

Postby Eugene » Sun Dec 19, 2021 8:33 pm

Remove the tunnel cover located between the operators knees to get to the clutch.

There are two pucks located on the back side of the pressure plate. The pucks stop the pressure plate from turning when the clutch is depressed. Easy to adjust, inexpensive, and easy to replace.
I have an excuse. CRS.

jensenracing77
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Re: Ignition coil drops to 0 volts when starter engages ???

Postby jensenracing77 » Sun Dec 19, 2021 9:08 pm

For no volts at the coil during cranking I suspect the wires on the ignition switch are hooked up wrong. Be sure the wire from the coil is hooked to the ignition terminal and not the Batt terminal. The Batt terminal will power things when the key is on but not while it is cranking. This allows all the amperage they can get to go to the starter. There is another terminal that will power the ignition and has power even when cranking. It is possible it is a bad ignition switch but I am betting the wire was put on in the wrong place.

Eugene
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Qu

Postby Eugene » Sun Dec 19, 2021 10:03 pm

I'm going with faulty ignition switch. Original poster said that he had the tractor previously running.

BishopBowyer. Now that you have 2 posts you can access the free, down loadable, manuals. Top left of page, Quick links.
I have an excuse. CRS.

Gary Dotson
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Re: Ignition coil drops to 0 volts when starter engages ???

Postby Gary Dotson » Mon Dec 20, 2021 8:29 am

It sounds like a bad switch to me, as well, because it pops right off, sometimes, most times not.

jensenracing77
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Re: Ignition coil drops to 0 volts when starter engages ???

Postby jensenracing77 » Mon Dec 20, 2021 9:18 pm

When the ignition is hooked to the wrong terminal it will rarely start but will now and then. When you let off the key at just the right time, you will get spark right when it was needed and allow it to start. I had this same problem on a fork truck one time. The guy on the other shift put a new switch in it and I didn't know it. Took me a couple hours to figure it out. A couple years later I did the same thing myself on an old car. Not saying that is the problem 100% but it is something to check before buying a switch.

Just take the switch out and ohm each position to make sure. If you have continuity on the ignition terminal when you turn the key to start position and the on position then the switch is good.

Shovelhead
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Re: Ignition coil drops to 0 volts when starter engages ???

Postby Shovelhead » Tue Dec 28, 2021 11:44 pm

My 154 was the same way, replaced the ignition switch and had the same problem.Checked my wiring and the 12v coil wire went to the switch “on” position, starter solenoid to the “start” position. I ended up changing the starter solenoid to a 4 wire type and ran a second wire between the coil 12+ terminal to the solenoid “ign” terminal. Works fine now.
Shovelhead

‘72 IH Cub Lo-Boy 154
‘81 IH 284 Diesel
‘86 Wheel Horse 416-8


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