B26 stalls under any acceleration.

[MikeHarpursville]

i am new to tractors and diesel. I bought a B26 with 960 hours at an auction. Sadly I am starting with issues. The engine stalls out whenever I give it much gas above idle. I can godrive it as long it is just above idle. Any more gas than that and it konks out. I tried adding power service diesel clean, I replaced the fuel filter. It was very gunky. The fuel seems to be running clean from the tank but I still get stalling. I assume I have to clean the rest of the fuel system out but cannot find any good videos on the B26. Or maybe someone has a different idea about what is happening...... Thanks.

 

[85Hokie]

Check you seat switch - I bet it thinks you are not in the seat and any movement will kill the engine.

 

[North Idaho Wolfman]

Lets clarify something, when you say "give it gas" are you talking about stepping on the HST pedal, or are we talking about the throttle lever on the right side? (bottom pic)

If it's the HST pedal Sounds like you have either a seat switch issue or an HST switch issue.

If it's the throttle lever on the right side won't raise the Engine RPM's then you have a fuel issue.

 

[MikeHarpursville]

Thank you for the quick answers! I am glad I signed up on here! I have heard of the seat switch issue. I disconnected and reconnected it. I am thinking it is not that because it is not killing the engine it is a slow death and if I stop moving it will recover. An additional fact I found yesterday is that as I was testing it, it was stalling on the steeper parts without me pressing on the HST any more. I had to stop and let it recover to keep from stalling out. If it is the seat is there a way for me to isolate the issue to see if that is it? Also how do I remedy that issue? The throttle increases the RPMs just fine. I have even tried driving under different throttle settings to see if that made any difference.

If its it the HST - That is out of my knowledge base and I also fear I got sold a lemon... arg. I paid 20k for this because I can't afford the new price. I knew it was possible to et stuck with an undisclosed problem. I hope it's not expensive. On the bright side - this is a good way to learn about the machine quickly.....

Do you have any advice on how to trouble shoot the HST switch? I will try to read up more on that in the meantime. Thank you again for your help.

 

[MOOTS]

Thank you for the quick answers! I am glad I signed up on here! I have heard of the seat switch issue. I disconnected and reconnected it. I am thinking it is not that because it is not killing the engine it is a slow death and if I stop moving it will recover. An additional fact I found yesterday is that as I was testing it, it was stalling on the steeper parts without me pressing on the HST any more. I had to stop and let it recover to keep from stalling out. If it is the seat is there a way for me to isolate the issue to see if that is it? Also how do I remedy that issue? The throttle increases the RPMs just fine. I have even tried driving under different throttle settings to see if that made any difference.

If its it the HST - That is out of my knowledge base and I also fear I got sold a lemon... arg. I paid 20k for this because I can't afford the new price. I knew it was possible to et stuck with an undisclosed problem. I hope it's not expensive. On the bright side - this is a good way to learn about the machine quickly.....

Do you have any advice on how to trouble shoot the HST switch? I will try to read up more on that in the meantime. Thank you again for your help.

Seat and HST switch is like you turned key off. Sounds fuel related to me. Check all fuel lines for good flow, filter elbow is known to collect trash. Electric lift pump working and giving good pulses?

 

[Russell King]

You can try to find a Work Shop Manual (WSM) at this link or on eBay

www.kubotabooks.com

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You might be able to use one from a similar tractor to get an idea of how to troubleshoot the switches. They may be simple open and close switches or more complicated double switches.

Anyway the easy way is to figure out how the switch operates and test it with a continuity meter to see if it is working correctly. You may also be able to bypass the switch with a wire jumper to eliminate the switch from the circuit. I would start by cleaning the switches with some type of spray contact cleaner after you remove the dirt and grass junk that is probably caked up around them.

Good luck

 

[85Hokie]

So you said " The throttle increases the RPMs just fine. "

thus the engine is getting fuel! If it runs up the rpms range to WOT then the problem is not a fuel problem - it is a switch problem.

Different tractor but same problem - in my BX25D when I bought it - I would slide forward in the seat to look over the FEL .... and the engine would cut out. I needed to be IN the seat well to place pressure on the occupant seat switch.

What range are you moving in? you have 3 ranges...... any uphill should be in LOW gear - and HIGH should be used when moving on flat ground.

 

[chim]

What 85Hokie said, especially the last paragraph. If you are new to HST's the "Go" pedal isn't like an accelerator pedal. It functions more like a seamless gearshift. As you increase pressure on the pedal it behaves like a manual transmission trying to start up a hill in fourth gear.

Range selection is important. The HST's I've used don't like hills in high gear.

 

[Russell King]

I am not 100% sure it is NOT a switch but the description of a slow death does sound like it is fuel.

But the switches do activate some type of fuel shutoff solenoid (as far as I know) to shut the tractor down, same as the key switch. So I am thinking two things might be possible, the solenoid is not holding closed well and is letting the engine die slowly, or the switch is sending intermittent stop signals.

I think one thing that could be tried is to figure out how the solenoid shuts the tractor down and then hold the fuel on and see if that keeps the tractor running. Then, if so, figure out what is failing, switch or solenoid.

 

[whitetiger]

A simple test: remove the fuel shut-off solenoid from the injection pump and plug/tape over the hole. Run the tractor and see if it stalls or continues to run.
If it still stalls, it is a fuel delivery issue; if it runs well, it is electrical.

 

[MOOTS]

So you said " The throttle increases the RPMs just fine. "

thus the engine is getting fuel! If it runs up the rpms range to WOT then the problem is not a fuel problem - it is a switch problem.

Not necessarily. Had a mower at work, would run fine at any RPM sitting still. Slow death once started moving. The electric lift pump was clicking and clacking, but not pumping. Replaced it, all was well.

 

[Scm]

I disconnected and reconnected it.

Someone will correct me if I'm wrong, but I don't believe you can just disconnect it and the tractor will continue to work. I think the system notices the switch is missing. I super glued mine in the down (seated) position and all my problems disappeared.

 

[Garvini]

it Sounds like the HST switch to me…I had the same problem…the switch is under the floor connected to the pedal linkage…it sits in a “U” shape bracket held in by a lock nut
mine had come loose and came out of the bracket
all I had to do is put it into position and tighten the lock nut

 

[North Idaho Wolfman]

Someone will correct me if I'm wrong, but I don't believe you can just disconnect it and the tractor will continue to work. I think the system notices the switch is missing. I super glued mine in the down (seated) position and all my problems disappeared.

You can, if you short the wires together.