# 20hp rider stalls



## mevslawn (May 7, 2012)

I have searched all over for an answer but found nothing....my riding mower will ride fine but once I engaged the blade it will die.....however, in neutral, the engine runs fine even if the blades are engaged....I would move the gear to forward and once I let the clutch go, the engine will die....

Basically, if in forward with clutch released and blade engaged, the engine will shut off....any thoughts.....thanks


john


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## Bill Kapaun (May 8, 2007)

Probably a bad/misadjusted/disconnected seat switch.


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## mevslawn (May 7, 2012)

thanks....I didnt know the switch was dependent on both the "moving" forward and engaging blade....I thought it was either or....I will look into it maybe tomorrow.....its not my mower, just helping a retired person out with his mower....

any other thoughts.....thanks


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## mevslawn (May 7, 2012)

looks like you're right....the panel by the seat has a lever for neutral, forward and reverse....if that lever touches the metal hook underneath the panel, the engine shuts off....when I put the mower in forward with the blade engaged, the lever touches the hook and everything shuts off....

I disconnect the yellow wire that connects to the hook and everything works great....I recall openning the panel to look at how the cables are wired and I thought I put everything back to normal, now I'm not so sure....

I have attached a sketch of the panel (top view and side view)....what is this design for....is the hook suppose to touch the lever when in forward mode.....


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## Bill Kapaun (May 8, 2007)

I'm sure it's part of the kill circuit to make sure you are in the seat when moving with the blades engaged.

I have absolutely no idea of what model tractor you have to see if there is a schematic available.

Your symptoms are typical of the solutions mentioned in my first post however.


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## jhngardner367 (Apr 5, 2011)

Bill,....is it possible he got the "hook" on backwards? That would cause it to kill in forward,instead of reverse,as it's supposed to.


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## Bill Kapaun (May 8, 2007)

jhngardner367 said:


> Bill,....is it possible he got the "hook" on backwards? That would cause it to kill in forward,instead of reverse,as it's supposed to.


I'd suggest asking the poster.


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## Country Boy (Mar 18, 2010)

The metal tab you mention is the safety switch for the reverse mowing system. They don't want you to mow in reverse, so they have that tab there that makes contact with the shift lever when you put it in reverse. If the deck is on, and the shift lever hits that tab, the engine will shut off. The tab should only touch the lever in the reverse position, so if it is making contact in the forward position, then it is either bent or installed wrong. If you are the only one using the machine, you can disconnect that wire and zip tie it up out of the way and the mower will work fine. The only thing that won't function is the kill switch for when you try to mow in reverse. Newer tractors have systems that allow you to bypass the safety system by either turning a second key switch, or by pushing a button with the key in a certain position. Its basically so you don't back over your kids or pets when backing up and mowing.


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## mevslawn (May 7, 2012)

thanks everyone for the informative replies....I was confident I put everything back to normal when I lifted the panel to debug something else....I guess I didnt....for now, I have the wire disconnected and my friend said it works fine other than battery looks like its not charging.....thats another subject when I have time to investigate why.....again, thanks.....

btw, asked my friend if he wanted to redo the hook to kill the engine in reverse. he doesnt, he wants option to mow in reverse.....


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## dangeroustoys56 (Jul 26, 2010)

If the tractor doesnt have a voltage regulator , most likely its a bad diode inline from the stator or a bad stator . The diode is a 'one way' switch - if its bad, the battery wont charge , but actually discharge.

When i bot my 92 white brand new - it had that saftey - no mowing in reverse. After being irratated many times - i unhooked it , i didnt have any small kids or pets around to worry about - i suppose its at your own discretion on unhooking them.


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## Bill Kapaun (May 8, 2007)

dangeroustoys56 said:


> If the tractor doesnt have a voltage regulator , most likely its a bad diode inline from the stator or a bad stator . The diode is a 'one way' switch - if its bad, the battery wont charge , but actually discharge.
> 
> When i bot my 92 white brand new - it had that saftey - no mowing in reverse. After being irratated many times - i unhooked it , i didnt have any small kids or pets around to worry about - i suppose its at your own discretion on unhooking them.


The diode can be better described as a "Check Valve". It allows current flow in one direction, but not the reverse.
The alternator puts out an AC voltage. The diode allows the "positive" pulse of the sine wave to "flow", but not the "negative" part.

A bad diode "might" allow current to flow in reverse (even good ones allow a negligible amount to flow) but it may do absolutely nothing if it's "blown. There's different ways a diode can be "bad".


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## dangeroustoys56 (Jul 26, 2010)

You can get new diodes at radio shack - theyre super cheep , just make sure its for 12volt .


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## Bill Kapaun (May 8, 2007)

dangeroustoys56 said:


> You can get new diodes at radio shack - theyre super cheep , just make sure its for 12volt .


So you're not going to worry about current carrying capacity, PIV etc.

Bad information is worse than no information.
'


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## dangeroustoys56 (Jul 26, 2010)

Then whats your fix?


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## Bill Kapaun (May 8, 2007)

Maybe actually trst the alternator would be the FIRST step.

Just because a diode is 12v doesn't mean it'll work. 
RS does have a diode or 2 that might work if it's only a 3 AMP charge system. They have a LOT more that won't.

Since the OP still hasn't even said what this tractor is and that the charging problem was for a later time, it's pretty much a MOOT POINT!


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## mevslawn (May 7, 2012)

thanks everyone for the proactive response.....

finally had some time to look at the charging issue....measured the voltage before starting mower....its roughly 12.7V....after starting up the mower, there is no increase....it still 12.7V....

There is a red/white cable which I think is the connection to the "alternator"...is this correct....I have attached two pics showing the wiring....

On pic wiring1, I disconnected the wire and measure the voltage there...with the mower on, I'm measuring 25VAC and ~20VDC....is this normal....not sure if the DC measure is correct.....

Where is the diode or voltage regulator located base on the pics...thanks


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## Mickey (Aug 14, 2010)

I'm pretty much in agreement with Bill.

As for 12V rating for a diode, asking for trouble here. The voltage rating is typ the max voltage the devise can safely handle. I'd want something in the 30-45V rating as AC voltage from the alt is more like 25V. What is important is the current capacity. Like with the voltage rating, the capacity rating is nom max. Current rating need to exceed the current rating of the alt by about 2x.

Not sure of other components in the charging circuit but voltage at the battery should rise above the 12.7V seen on the battery when at rest. If it doesn't, something is amiss. Oh, 12.7V on the battery is typ what a 12V nom LA battery is when fully charged and has been resting for a few hrs.


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