MF 50 gas will run, but suddenly, but won't crank..why??

Hay hay hay

Well-known Member
I hate to ask this. My old MF50 gas ran great today. Started and stopped, 20 times ran great,but suddenly after turned off... would not crank. Rolled it 10 feet downhill, popped the clutch..and started right up, and ran fine.

Parked it ...same problem...nothing, no crank, no noise.

Here is what I have done. Jumped from Pos. Batt terminal to starter...turns engine over normally. Starter OK?

If the jumper to the starter works, then the neg. terminal cable must be well grounded?

It has a new neutral safety switch, rechecked it and still works fine.

Key switch when turned on.... shows no voltage to Neutral safety switch and no lights in any position.

Battery shows 12 volts (with meter).

Tried a jumper from Batt. Pos. to solenoid...nothing.

Ideas? Key switch? Solenoid?


.
 

Key switch is an easy test with a meter. And its cheap.

From there, test voltage at the solenoid. Key to start, should have voltage on the thinner wire. My guess is solenoid as they have a large copper disk inside that becomes pitted and burnt with age.
 

First things first- check and clean battery terminals, ground and starter lug. Check and clean solenoid ends. Ignition switches go bad over time. Look for cracked wires too. My 65 is a rats nest of cracked wires and gives me the same issues.
 
Update. Turned on the key. Put a jumper between the positive battery terminal and the small wire post on the solenoid.

Eureka!!!Tractor started right up. Ran fine, only killed when I turned the key off.

So..... it is not the starter or the solenoid or the cable connections.

Any ideas? bad starter button? Blown fuse? The harness is like a rats nest of old wires and stuff.

I am at a loss.
 
With the key on, you should have power to the start button. When you push the start button, power should go to the neutral safety switch and then to the solenoid. Either your start button, or neutral safety switch is bad or you have a bad connection in the three wires that connect them all of them.

Probably my first quick test would be to pull the wires out of the safety switch and make sure I have power there when I push the start button. If yes, I would then temporary connect the wires from the safety switch together and see if it fires up. If yes, time for a new safety switch. Make doubly sure the tractor is in neutral with the safety switch bypassed, and if it is bad, don't leave it bypassed, get a new switch.

Dan
 
The whole scenerio was a little baffling. Yesterday I hit the solenoid with a jumper cable from the positive battery terminal and the tractor fired right up. Today, I tried it again and the solenoid would not send power to the starter.
Tried it several times..nothing....no luck.

So...I went out and bought a new solenoid..installed it.

Success. fired up the first time and the 20 start attempts after that.

Thanks guys for your very helpful input, which helped me isolate and fix the problem.
 

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