Kubota B7800 Cranks but won't run

[Kevin Staton]

My tractor has done this twice now. It starts, runs for about a minute and then dies. Afterward, it won't run. It will crank but won't run. Had been having issues with the fuel cutoff switch (no click on key turn) so I replaced it. Started and ran fine several times after.

I went to use it this weekend and it started, ran for about a minute and then died and now it won't run. Cranks but wont run. Whiteish smoke from exhaust.

Jumpered both seat switches - same thing.
Engage HST pedal - no crank
Engage PTO - no crank
Disengage clutch - no crank

Any thoughts on other safety switches to check? Fuel pump? (filter housing is full of fuel)

 

[Ed ke6bnl]

When I first picked up my used b7800 filled with fuel and started ran about 3 minutes and turned off not start. Pulled the in hose to the filter and drain off about a cup of water reconnected and start and has run great for the last year. Now this tractor sat for 6 years next door to my place in the open air. I have since put in the stock filter, it had auto inline filter. Just a thought.

 

[Kevin Staton]

Finally found the problem!

After having it at the dealership where they cleaned the tank and replaced the fuel cutoff solenoid (twice) amoung other things, I was able to track the problem to the controller. 6C190-55510 CONTROLLER(OPC)

To replace it you have to remove the gauge cluster. Remove the tachometer cable from the holder on top of the engine first to get enough room to then remove it from the tach. Then remove the one nut holding it, unplug it then reverse the process to the install the new one.

Really hard to track down the symptoms correctly. The most obvious was that the solenoid wouldn't click when the key was turned. It would occasionally die while running and not restart. What finally pointed to the controller was leaving the ignition on after it died. Eventually you'd hear the fuel cutoff solenoid click and then you could restart it. This is caused by timer circuit in the controller. When you turn off your B7800 a circuit is activated that energizes the fuel cutoff solenoid to stop the flow of fuel to the engine. Then after a period of time the circuit is de-energized so it doesn't run down the battery.

Because the engine would die and then reset to run on its own, it pointed to this circuit.

Best of luck to whomever has this problem. I hope this helps.

PS - Any dealership that tells you to hit your fuel cutoff solenoid repeatedly to get it activate doesn't deserve your business!

 

[CH4Ohio]

Thanks for the report. Good to know where that controller is located and symptoms.
Just FYI, the fact that it was cranking indicated that the seat switch, clutch safety, PTO safety, etc. were all ok. Otherwise it wouldn't have even cranked.

I believe your report here will also apply to the older model (but same tractor) B2910.

Thanks!

 

[Henro]

I believe your report here will also apply to the older model (but same tractor) B2910.

Thanks!

I don’t think it will. My B2010 doesn’t have an OPC module.