mx5000 wont start

[Tim131]

I have a MX5000 not sure of the year
It will not start as long as the key is in start position but will sometimes take off as you release it back to run position and sometimes you have to crank and release several times before it will start Any ideas or hopefully quick fixes?

 

[Tim131]

I just tested the power going to fuel pump solenoid and it looses power when cranking but still don't know why

 

[Dave_eng]

What is confusing is that the available free WSM for the MX5000 do not even show a stop solenoid in the wiring diagram nor in the electrical section. One shows in the parts illustrations.

Tractordata.com says the MX5100 is the next series of tractor and its WSM wiring diagram includes a stop solenoid.

I am not certain how related the two tractors actually are.

The 5100 seems to have more technical safety system which includes an OPC or operator presence controller. This system includes a relay to power the stop solenoid.

I suggest you first look for a relay for the stop solenoid. If there is one swap it for another identical relay.

The solenoid should be powered when the key is both in ON and in START. Is there anything else on the tractor which stops working when the key is in START.

If so the key switch would be suspect.

Dave

 

[whitetiger]

Here is the starting schematic for a MX5000 w OPC

 

[whitetiger]

Here is the wiring diagram for M5000 with OPC

 

[Dave_eng]

Tim
The info provided by Whitetiger is most helpful.

It confirms there are two independent coils inside the stop solenoid.
The coils need to be tested following the procedure below.
Each terminal on the electrical connector needs to have its resistance to the solenoid case measured.
The coils have significantly different resistance values.
I know you said there is no power in the start position but it is important we verify that both coils within the solenoid are OK.

The power for the solenoid, which I have marked with a blue line, comes from the battery with no fuse.
The solenoid power first flows to a relay shown as #11.
The relay trigger control is marked with a red line.
The key switch #2 has a number of circles within boxes.
This is telling you which terminals of the switch are connected at different switch positions.
The relay trigger wire is connected to the AC or ON position of the switch so the engine stop relay should be powered with the key ON.
The same trigger wire becomes connected to the power in the switch in the start position.

If as you have stated the power supply to the solenoid disappears in the key START position then the key switch becomes suspect.

However, please check the solenoid coils first.

I have attached WSM pages dealing with checking the key switch.

Dave