BX 23, sputtering and hard/won't start

safar · Apr 16, 2023

So, more progress on this and also explains the hard starting issue;

This is my understanding on how the solenoid appears to work (don't have a WSM - I wish I did and might try and look for one).

The plunger is normally in the in/retracted position.
When you turn on the tractor it should stay in/retracted and get no power.
When you turn off the tractor there is 12v that goes to the solenoid that pushes the solenoid plunger out, which cut off the fuel and shuts the engine down, there is a relay somewhere that keeps the 12v of power for 6 seconds and then the plunger retracts back in.

Connector voltage:
If the above is correct, the solenoid should not get any power to it when starting / cranking and only get the 12v power for 6 seconds when you turn the key off.

Here's what's happening with mine.
When you turn the key just before you crank, the solenoid is getting 12v of power that pushes the plunger out and it stays out for 6 seconds and then retracts.

That explains the hard starting as the plunger is getting pushed out, cutting off fuel and if you keep cranking for 6 seconds, the plunger retracts and the engine starts.

Sometimes once it gets started and you let go of the key, it gets 12v of power, pushing the plunger out, explaining why letting go of the key sometimes switches off the engine.
Other times it seems to get the power for a fraction of a second and pushed the plunger out again and back in quickly.

If it doesn't push back out the engine stays on.

If it pushes out and in quickly, that sputters the engine, but it stays on.

If it keeps pushing in / out (which it seems to do for a few seconds on occasion), the engine sputters and either stays on or turns off based on what the plunger eventually does.

Since I now have 2 solenoids I was able to test this with one outside and just connected to the wiring harness, and the other screwed in place to prevent fuel shooting out.

--
So, the solenoids are fine, the issue is either at the key switch or somewhere in the wiring, but I don't know enough to know how to start understanding.

I'll try and get a key switch replacement, but wondering what your thoughts are on possibility of a wire shorting somewhere and if so, how do I go about diagnosing this?

This winter we had a lot of rain and with the tractor outside, that might be part of what caused this.

I know it's a bit of a lengthy explanation, but just wanted to try and be as clear as I could.
Thank you all - appreciate any thoughts.

JWR · Apr 16, 2023

Boy, I think you have now figured out more about the sequence of events with the fuel shutoff solenoid than the rest of us knew ! Certainly more than I. I would not go changing out the key switch just yet. Sounds like a sequence is out of whack and that is probably a relay rather than the key switch.

K5lwq · Apr 17, 2023

safar said:
So, more progress on this and also explains the hard starting issue;

This is my understanding on how the solenoid appears to work (don't have a WSM - I wish I did and might try and look for one).

The plunger is normally in the in/retracted position.
When you turn on the tractor it should stay in/retracted and get no power.
When you turn off the tractor there is 12v that goes to the solenoid that pushes the solenoid plunger out, which cut off the fuel and shuts the engine down, there is a relay somewhere that keeps the 12v of power for 6 seconds and then the plunger retracts back in.

Connector voltage:
If the above is correct, the solenoid should not get any power to it when starting / cranking and only get the 12v power for 6 seconds when you turn the key off.

Here's what's happening with mine.
When you turn the key just before you crank, the solenoid is getting 12v of power that pushes the plunger out and it stays out for 6 seconds and then retracts.

That explains the hard starting as the plunger is getting pushed out, cutting off fuel and if you keep cranking for 6 seconds, the plunger retracts and the engine starts.

Sometimes once it gets started and you let go of the key, it gets 12v of power, pushing the plunger out, explaining why letting go of the key sometimes switches off the engine.
Other times it seems to get the power for a fraction of a second and pushed the plunger out again and back in quickly.

If it doesn't push back out the engine stays on.

If it pushes out and in quickly, that sputters the engine, but it stays on.

If it keeps pushing in / out (which it seems to do for a few seconds on occasion), the engine sputters and either stays on or turns off based on what the plunger eventually does.

Since I now have 2 solenoids I was able to test this with one outside and just connected to the wiring harness, and the other screwed in place to prevent fuel shooting out.

--
So, the solenoids are fine, the issue is either at the key switch or somewhere in the wiring, but I don't know enough to know how to start understanding.

I'll try and get a key switch replacement, but wondering what your thoughts are on possibility of a wire shorting somewhere and if so, how do I go about diagnosing this?

This winter we had a lot of rain and with the tractor outside, that might be part of what caused this.

I know it's a bit of a lengthy explanation, but just wanted to try and be as clear as I could.
Thank you all - appreciate any thoughts.

This is what I was thinking was happening. The reset for the relay is 12v supply on the signal wire. When the switch is turned to off it knows to fire for 6 seconds. If the supply wire is not making good connection then it would do as you are experiencing.

I would look closely at connectors for corrosion that could be a bad connection. A faulty timer relay could be to blame as well.

Very good job tracking down the problem. You are getting close now.

dodge man · Apr 17, 2023

If it’s in the wiring about all you can do is trace the wires. Easier said then done as you may have to take a lot of things apart to get at them. It could be a mouse chewed threw or water or corrosion in a connector. I hate wiring problems.

dodge man · Apr 17, 2023

Another thought just completely disconnect the factory wiring and run a new wire with a manual button to turn it off and on.

safar · Apr 17, 2023

Boy, I think you have now figured out more about the sequence of events with the fuel shutoff solenoid than the rest of us knew !

Thank you - you guys gave me a direction to work toward, which I really appreciate about the forum. I'm always willing to put in the work, but the experience of others helps point you in the right direction.

I've never liked when someone just comes and ask a question and expects others to solve it for them. You are all so generous with your time and I really want to convey how much it's appreciated.

I would look closely at connectors for corrosion that could be a bad connection. A faulty timer relay could be to blame as well.

I'm really thinking that's what it likely is - but just have to work through this one step at a time. I don't have pins, clips, connectors, wires etc - so need to purchase some parts and work on this later this week - but i'll be sure to update once I have more info.

Another thought just completely disconnect the factory wiring and run a new wire with a manual button to turn it off and on.

It's a good thought but after how much this problem has stressed me out, I really want to get it fixed right. Plus I think I would make it difficult for anyone else in the family wanting to use the BX.

I also worry i'll snag the switch some how and turn off the tractor at the most importune time, like while mowing or using the backhoe.

I tend to put gloves, hats, sunglasses on the dash and i'm sure I'll often mess it up.
Then I also worry, i'll use the button to turn off the engine, but forget to turn the key back and drain the battery. Better to just do this right.

safar · Apr 17, 2023

Oh - One more question.
If you were to plan new wiring, where would you buy wires, connectors, clips etc?
I have none of these (apart from fuses) and want to buy some quality products - Amazon is so inconsistent on quality and didn't know if there was places you might recommend.
I'll probably buy quite a bit extra parts as a lot of the lights on the BX don't work and other places the wires look like they could need replacing.

dodge man · Apr 17, 2023

An auto parts store has some of that stuff. A lot of the connectors are going to unique to your tractor. A lot of times if it is a connector you can take it apart and clean it. If seen connectors that were an obvious problem where they were turning green.

/pine · Apr 17, 2023

Know this has the symptoms of a fuel related issue...but on the outside chance...you might also check for possible corrosion or shorting on one of the safety switches...