No start issue

[dmoore]

So I cut our 4 acres today with my 2006 B7800. Shut it down for an hour for lunch. Went to start it again to wash out the deck and nothing. Fuel solenoid clicks but no starter engagement. First time in 16 years this has ever happened. So I am thinking one of the safety switches must be the problem or blown starter fuse at the starter. Fuse checked out good. I grab a test lead with alligator clips and jump out the starter solenoid while pushing in on the clutch and key in the run position. Nothing. I then tie the seat down as to depress both seat switches. I jump the solenoid again and it starts. As soon as I untie the seat and 2 seconds later it shuts down. The PTO is disengaged if your wondering. So I jump out both seat switches and still the same thing. I am now wondering if the clutch safety switch is the culprit. It seems to be closing the switch externally. Tough to get to the boot to pull it up far enough and jump it out. This is where I stopped for now. At least I got it back in the barn. The PTO safety switch could also be the issue. I looked down in that area and there are two. Thoughts?

 

[mikester]

Dead battery. Corroded contacts. Bad ground.

 

[GreensvilleJay]

Without the wiring diagram it's near impossible to say exactly what is causing the 'no start' condition.
old tractor...could have a 'frayed or chewed' wire finally gave out, crap in some switch,loose connection,??

 

[dmoore]

Dead battery. Corroded contacts. Bad ground.

Battery is perfectly fine, I can bypass the starter solenoid and it cranks fast. Tractor is immaculate and is stored in my climate controlled building since I bought it new.

 

[dmoore]

Without the wiring diagram it's near impossible to say exactly what is causing the 'no start' condition.
old tractor...could have a 'frayed or chewed' wire finally gave out, crap in some switch,loose connection,??

Are there wiring diagrams posted here?

 

[Henro]

Are there wiring diagrams posted here?

You can download the workshop manual from kubotabooks.com. The B7800 is a supplement to the B2710/2910 WSM, in the back. A wiring diagram/schematic is found there.

 

[dmoore]

Thank you for that information will do!

 

[mikester]

Battery is perfectly fine, I can bypass the starter solenoid and it cranks fast. Tractor is immaculate and is stored in my climate controlled building since I bought it new.

Now that you've ruled out typical problems using logic you should simply start buying new parts for your immaculate tractor stored in the climate controlled building. Use the following order:
1. replace starter solenoid
2. replace key switch
3. replace starter
4. replace fuses

 

[GreensvilleJay]

jumper +12 to control tab of starter solenoid, if it spins, solenoid/starter is fine.
follow 'control wire' back to where ever it goes(some safety switch ?),test there.

 

[woodman55]

So I cut our 4 acres today with my 2006 B7800. Shut it down for an hour for lunch. Went to start it again to wash out the deck and nothing. Fuel solenoid clicks but no starter engagement. First time in 16 years this has ever happened. So I am thinking one of the safety switches must be the problem or blown starter fuse at the starter. Fuse checked out good. I grab a test lead with alligator clips and jump out the starter solenoid while pushing in on the clutch and key in the run position. Nothing. I then tie the seat down as to depress both seat switches. I jump the solenoid again and it starts. As soon as I untie the seat and 2 seconds later it shuts down. The PTO is disengaged if your wondering. So I jump out both seat switches and still the same thing. I am now wondering if the clutch safety switch is the culprit. It seems to be closing the switch externally. Tough to get to the boot to pull it up far enough and jump it out. This is where I stopped for now. At least I got it back in the barn. The PTO safety switch could also be the issue. I looked down in that area and there are two. Thoughts?

I am leaning towards the pto switches, I am thinking the tractor thinks the pto is engaged. Does your tractor have a indicator light in the dash ? That could be one switch and the other for the start circuit. A test light would be very useful.

 

[GreensvilleJay]

I grabbed the wsm, there's 3 safety switches ( clutch,pto, hst) that all have to be closed to ground the starter relay. you should be able to jumper to bypass the 3 switches. if it starts yo KNOW it's one of the 3 switches and/or their wiring.
if the 'preheat' lamp comes on ,then the main switch is supplying +12 to the starter relay

 

[woodman55]

Thank you for that information will do!

Lots of great info in the service manuals, well worth the money.

 

[Henro]

Battery is perfectly fine, I can bypass the starter solenoid and it cranks fast. Tractor is immaculate and is stored in my climate controlled building since I bought it new.

Curious, how did you bypass the starter solenoid?

 

[B2710HSD]

So I cut our 4 acres today with my 2006 B7800. Shut it down for an hour for lunch. Went to start it again to wash out the deck and nothing. Fuel solenoid clicks but no starter engagement. First time in 16 years this has ever happened. So I am thinking one of the safety switches must be the problem or blown starter fuse at the starter. Fuse checked out good. I grab a test lead with alligator clips and jump out the starter solenoid while pushing in on the clutch and key in the run position. Nothing. I then tie the seat down as to depress both seat switches. I jump the solenoid again and it starts. As soon as I untie the seat and 2 seconds later it shuts down. The PTO is disengaged if your wondering. So I jump out both seat switches and still the same thing. I am now wondering if the clutch safety switch is the culprit. It seems to be closing the switch externally. Tough to get to the boot to pull it up far enough and jump it out. This is where I stopped for now. At least I got it back in the barn. The PTO safety switch could also be the issue. I looked down in that area and there are two. Thoughts?

sounds similar to a couple of problems I had on my b2710 with the hst pedal switch. firstly the switch actuation mechanism was worn so would not activate the switch in the "pedal neutral" position. secondly the switch adjustment screw came loose and allowed the switch to move out of alignment with the actuation mechanism. lying on my back under the hst pedal side allowed me to see the operation of the switch to work out what was happening. Also the "pedal neutral" position on mine was in such a small envelope of operation that sometimes it was necessary to turn the key to the start position and slowly move the hst pedal to find the neutral start position.

 

[GreensvilleJay]

re bypass
he may mean bypass the starter relay. from the wiring I saw, power from ign sw goes to one end of a 'starter relay' and the 3 safety switches are in series from the relay to ground. You can 'bypass' them simply by jumping +12 on starter to the starter solenoid contact...

 

[Henro]

In case the WSM was not found, as I just had difficulty finding, although I downloaded it previously, the link follows. The B7800 section is at the back of the manual.

http://kubotabooks.com/AutoIndex/index.php?dir=Tractor%20Owners%20Manuals/&file=B2410_%20B2710_%20B2910_%20B7800_9Y011-13031%5B1%5D%20WSM.pdf

 

[Henro]

re bypass
he may mean bypass the starter relay. from the wiring I saw, power from ign sw goes to one end of a 'starter relay' and the 3 safety switches are in series from the relay to ground. You can 'bypass' them simply by jumping +12 on starter to the starter solenoid contact...

That is probably what the OP meant. Looks like there is no start relay on the B7800, just an output from the OPC to the starter solenoid, via a switch on the clutch pedal. Did not look further to see if there are other permissive inputs to the OPC. Certainly might be, as I believe the B7800 has a operator presence switch on the seat.

 

[dmoore]

re bypass
he may mean bypass the starter relay. from the wiring I saw, power from ign sw goes to one end of a 'starter relay' and the 3 safety switches are in series from the relay to ground. You can 'bypass' them simply by jumping +12 on starter to the starter solenoid contact...

precisely

 

[dmoore]

That is probably what the OP meant. Looks like there is no start relay on the B7800, just an output from the OPC to the starter solenoid, via a switch on the clutch pedal. Did not look further to see if there are other permissive inputs to the OPC. Certainly might be, as I believe the B7800 has a operator presence switch on the seat.

Correct, a run switch & a start switch. Both jumped out they are not the issue. I have not had time to jump out the hydro & PTO switches just yet. I am thinking one of them is the problem. Thank you for the responses. I am ordering a FSM tomorrow. After 16 years I guess I will need one.

 

[Mark_BX25D]

Now that you've ruled out typical problems using logic you should simply start buying new parts for your immaculate tractor stored in the climate controlled building. Use the following order:
1. replace starter solenoid
2. replace key switch
3. replace starter
4. replace fuses

No. This is just firing the parts cannon. It's the most expensive and frustrating way to fix a problem, and usually takes the longest.

There is a lot more troubleshooting to be done. Getting those wiring diagrams is the first step.