Z-737 Stalling When Handles Pulled Back

[DeputyDawg]

I have a John Deere Z-737 mower. Lately when I use it and I am going forward and pull back on the handles it wants to and sometimes dies on me. I thought maybe it is fuel starvation and changed the fuel filter which didn't help. Now its to the point of shutting off so often I cannot mow with it. All the fluid levels are good and the air cleaner is good. Suggestions?

 

[Deleted member 97405]

I have a John Deere Z-737 mower. Lately when I use it and I am going forward and pull back on the handles it wants to and sometimes dies on me. I thought maybe it is fuel starvation and changed the fuel filter which didn't help. Now its to the point of shutting off so often I cannot mow with it. All the fluid levels are good and the air cleaner is good. Suggestions?

How does the power seem otherwise?
If you mess with the choke when the engine wants to die, does it make any difference?
Is it sputtering, then die, or does it shut off as if you turned the key off?

*These machines were notorious for debris getting stuck in the cylinder heads, which would overheat the heads and seize the valves up. The engine would then only run on one cylinder.

Can you give me anymore finer details on what happens when the engine dies?
If you can post a video of it shutting off, that would be awesome!
I am happy to help.
Thanks!

 

[DeputyDawg]

When it starts to die I sometimes can move the handles outward and inward to keep it from shutting off but that is temporary and it still shuts off. The engine does not pop or backfire. I noticed yesterday that when pulling back on the handles and it start to die that the Orange light for the battery flickers. Would a bad battery make it do this? The battery is not that old. I have no problem starting it and it fires right up. I tried to choke it as it died to see if it just needed more fuel but that didn't make a different. When I do the choke it sputters and then dies. My impression at first was that it was fuel starvation and that is why I replaced the fuel filter. When running I can turn it off with the key and it shuts off normal.

 

[Deleted member 97405]

When it starts to die I sometimes can move the handles outward and inward to keep it from shutting off but that is temporary and it still shuts off. The engine does not pop or backfire. I noticed yesterday that when pulling back on the handles and it start to die that the Orange light for the battery flickers. Would a bad battery make it do this? The battery is not that old. I have no problem starting it and it fires right up. I tried to choke it as it died to see if it just needed more fuel but that didn't make a different. When I do the choke it sputters and then dies. My impression at first was that it was fuel starvation and that is why I replaced the fuel filter. When running I can turn it off with the key and it shuts off normal.

Thanks for the info. I'm going to say your issue is electrical. If it were a fuel issue, the choke would have helped rather than killing the engine.
Some of the issues I have found over the years have been anything from a broken wire losing connection, a bad keyswitch, a PTO switch going bad, the switches at the control sticks going bad.
Any of the above could create an intermittent issue as you are describing.
Unfortunately, the only way to find it is to get a wiring diagram and start testing switches and inspecting all wire harness plugs, and ground connections.
As with electrical issues, the problem is probably a simple fix, but finding it can be aggravating.

A bad battery can do weird things, especially if your charging system is weak.
But usually, if the battery causes the engine to shut off, you wont be able to crank it right back up because the battery would be dead at that point.
So I'm going to rule the battery out at this point. Make sure your battery cables are tight and free of corrosion.
If it were at my shop, I would start by checking all your ground connections, and unplug and replug all harness and switch connections in hopes that it is just a dirty connection somewhere. If no change, then the electrical system will need diagnosed.
I can supply you with a wire harness schematic. The tech book has serial number breaks depending on which mower deck you have. If you could post your serial number and size of mower deck, then I can get you the right schematic.

Will

 

[bertsmobile1]

I have found the easiest way to find electrical problems is to pull the plugs at the switches then jump the socket with some patch cords.
If the problem persist with all of the switches bypassed then you have a short in the wires.

 

[Deleted member 97405]

I have found the easiest way to find electrical problems is to pull the plugs at the switches then jump the socket with some patch cords.
If the problem persist with all of the switches bypassed then you have a short in the wires.

Jumping safety switches is always something I would approach with caution.
You can easily send current to the wrong places if you don't know what you're doing, or worse yet someone could get seriously hurt with the safety system bypassed.
There are relays and diodes in this system as well.
I usually don't recommend a customer to do it unless they really know what they're doing.

 

[bertsmobile1]

Jumping safety switches is always something I would approach with caution.
You can easily send current to the wrong places if you don't know what you're doing, or worse yet someone could get seriously hurt with the safety system bypassed.
There are relays and diodes in this system as well.
I usually don't recommend a customer to do it unless they really know what they're doing.

Good point well taken
Keep forgetting that I know how to do it & others might not.
So for the benefit of DD
The switches make connections flat to flat not edge to edge.
The flats continue into the switch and get either joined together or disconnected by the plunger.
It is always prudent to remove the kill wire from the magneto and check it for voltage to ground.
'If you see voltage then you have crossed the wrong wires
and of course this is a diagnostic tool only .
If you are unsure get the JD manual.
While they are not inexpensive they are the best manual by a long shot and require zero skills or mechanical knowledge to use.
In fact they are more informative & better written than a lot of text books that apprentices are forced to read.
When it comes to the electrics, the manual tells you where all the parts are, how to st the controls to do the test where to test & what the results of each test mean.

 

[DeputyDawg]

Thanks for the feedback.

I had a suggestion from another forum that it may be the Seat Switch. So I unplug it and jumped it and that corrected the problem. I ordered a new switch.

Again, thanks for the replies.

ddawg