Engine starts cutting out after engaging mower deck

[Marko]

Hey folks,

I have a strange one here. I have a 1999 White (MTD) LT15 lawn tractor. I am having issues when lower / engaging the mower deck and having the engine start cutting out. If I raise the deck lever all the way (which stops the blades) the engine runs fine. I had the snowblower attachment in it this winter and did not have this issue when using the engagement lever to engage the auger. Tractor starts and runs great however the only issue is no matter what deck height I set the deck to , once I start engaging it the engines starts to quit. It first sounding like the deck safety switch was bad , so I replaced it with a new one. still no luck. I sprayed all electrical connections with electrical cleaner , still nothing. Though it might be a bade ground however outside of the battery ground could not find an other grounds. Why is this happening with the mower deck and not with the snowblower attachment. I am trying to bag my leaves and can not get the tractor to run with the mower deck engaged.

Help ! I do not want to rake

Mark

 

[rus_geek]

Do all of your blades rotate freely? If one of your spindles is sticking, it would create excess load on the engine and cause it to die. Will the engine run at lower RPMs and/or with partial choke?

It's a lot of work, but you could also try switching back to the snowblower to see if it fails under load with that attachment, now, too. You don't indicate whether it worked at all with the mower deck on this summer.

You could also try disconnecting the kill wire from the coil. If that fixes it, you have a bad ground somewhere. Please note that disconnecting that wire means the key will *NOT* stop your engine when you turn it off, so have another means of stopping it (fuel shutoff works eventually).

-rus-

 

[Marko]

Hey Rus ,

Yes both blades spin freely , the mower deck did this same thing last summer also however thought it was related to the safety switch. Snowblower attachment worked great all winter with no issues. Wouldn't a bad ground cause the same behavior with the snowblower attachment ? The tractor does not have a fuel shutoff , so If I test the kill wire option I'll have to install a fuel shutoff.

Mark

 

[jhwentworth]

Does your tractor normally kill the engine when you put it in reverse with the PTO engaged? If so, check the reverse engagement switch that should be near the base of the shift lever.

There should be a wire that kills the ignition, and another that powers the fuel shutoff solenoid if your engine has one. If you can locate the ignition kill wire try disconnecting it to test, you can always reconnect it to stop the engine.

 

[Marko]

Yes , the tractor has the reverse with the PTO / mower deck engaged safety switch. There is also a solenoid on the bottom of the carb.

So is the test disconnecting the kill wire on the coil. If the behavior goes away this would suggest a bad ground somewhere. If so is there a common place on these tractors for the ground ?

Mark

 

[jhwentworth]

Why would you think it's a bad ground? The ground seems to be working quite nicely to kill the engine. Look closely at the reverse switch, they can be pretty beat up. Same with the seat switch. I know you replaced your seat switch, but I'll bet your problem is somewhere between the reverse switch and the seat switch.

 

[Marko]

Both reverse and seat switches are clean and working correctly as when the mower deck is NOT engaged and the tractor is running fine , putting the tractor in reverse kills the engine and getting off the seat does the same thing. If these switches were the issue , I would think the same behavior would happen when using the engagement lever to engage the auger with the snowblower attachment , however this is not the case. The snowblower attachment works just fine. What is different between when the mower deck is engaged and the snowblower attachment ? What I have noticed is that this behavior will sometimes go away if I adjust the mower deck with the engagement lever and completely clears itself up with the lever is fully disengaged. This is very strange. I checked the clutch safety switch as well and that is working just fine. Tested this by leaving the tractor in gear without depressing the clutch petal. Tractor would not start and the light on the dash showing the foot brake lights up.

 

[dqdave1]

check clutch wiring for short; bare wires, etc. that might be causing problem. wiggle wires to see if you can get it to act up.
Check all linkages that mower attaches to tractor, looking for interference with wires.\
How is relay for pto clutch? mower may cause more amp load on relay than blower.

 

[Marko]

This tractor does not have an electric PTO , it has a manual engagement lever that engages the belt. So no electric relay involved here.

 

[GT2]

What about the possibility of something engine related? Poor gas, needs new plugs, water in the fuel bowl, engine needs tune up, partially plugged fuel jet etc.?

 

[Marko]

Thought of that , however used the tractor all winter for snow blowing and had no issues with this behavior. Changed plugs , fuel filter , air filter and cleaned carb. Tractor ran great all winter. Seems that something is happen when the mower deck is engaged that does not take place when the auger is engaged with the same lever.

 

[jhwentworth]

Marko, I wouldn't get hung up on why it worked with the snowblower. It isn't working with the mower, and that's what you want to fix. To eliminate enine issues try putting it in high gear and running up a steep grade; if it runs fine then it's a safety switch causing your problem. Locate the kill wire by following the wire from the reverse switch, and disconnect it.

Do you have a meter? Do you know the model number of your machine? Speculation on why it worked with the snow blower may not be that useful.

 

[Marko]

Tied a steep grade and tractor runs fine. I'll follow the wire from the either the seat switch or reverse switch back to the coil and disconnect it ? Yes I have a meter and the model number is 686 or 13A1686G190

Mark

 

[jhwentworth]

I've located a wiring diagram at Parts and Diagrams for White Outdoor 13A1686G190 LT-15 (1997) .
Looks like the ground path is yellow/black wire from reverse switch to deck switch (connects with another yellow/black wire from seat switch), out on yellow wire to ignition switch. A yellow wire connects the engine magneto to the ignition switch via a connection at the clutch switch. The engine kill function works by various combinations of the clutch, PTO, reverse, and seat switches grounding the magneto. Other combinations will prevent the starter from engaging.

I'd print a copy of the wiring diagram and use a meter to diagnose the problem. Look at the wiring at the PTO(deck) switch. There are two inputs at the upper leg: the seat switch and the reverse switch. Here the where the decision is made that if the seat is empty or reverse gear is selected, and the deck is engaged, the magneto is killed. Since the engine runs until the deck is engaged I'd say the problem is from the PTO (deck) switch back to the reverse or seat switches. Try disconnecting the yellow/black wires at the PTO (deck) switch.

 

[General Lee]

I had a similar problem. Ended up being low voltage on the battery.

 

[Marko]

jhwentworth - I check the continuity between the seat and reverse switches to the deck switch over yellow / black wire and all is Ok. Found no broken wires or an damage of the wire looms etc. Did notice that the battery is not 100% even though it started right up wonder if the low battery voltage condition that General Lee posted is the issue. I get a new battery and test again. Just out of curiosity , once the engine starts I though that the mag took over providing spark to the plug and not off the battery ?

 

[jhwentworth]

Low battery voltage doesn't seem like a viable issue here. Look at the wiring diagram; does it seem that the battery is the source for the ignition? Kill the mag, kill the ignition.

Disconnect the yellow wire at the deck switch.

 

[Marko]

The yellow / black wire is part of the wiring harness that plugs into the deck switch. So I'll have to get creative on how I disconnect this.

 

[Marko]

Wouldn't disconnecting the seat switch and reverse switch at their respective places solve the same things as disconnecting them at the deck switch. I'll give both a try but have a hard time believing that if I have full continuity on this is the problem. The seat and reverse switches are simple contact ones so testing them and seeing of there are issues with this is fairly easy.

I have to get a new battery anyway as having on the trickle charger for the afternoon did not yield anything.

 

[Sonny580]

I am fighting the same problem with a Dixon 4421, B&S 13 hp motor, electric clutch mower engagement ! I too wanted to bag leaves! LOL!---as soon as deck engage switch is flipped, motor dies!---Runs uphill full speed, full rpm, just dont turn mower deck on!---Got me stumped too ---NEVER had one do this before!---has new F&F battery fresh otta the store just put on it!---still got the problem!
Didnt mean to hijack your thread, but I am getting desperate here as good weather is not going to last much longer and I have a lot of yard to clean! thanks; sonny 580