B7800 will not start

[bshenanigan]

I bought my first tractor, a B7800, about a month ago. I have not been able to get it started.

I have checked
* Fuel is half full
* Oil is full
* Battery is ok
* Seat safety switch resistance changes when switch is flipped

What should I check next? As I am lost, I am planning on finding all the other safety switches and shorting them one by one to see if that is the problem.

I have noticed that when I flip the seat safety switch a relay(?) clicks towards the front of the tractor.

Symptoms are:
* Battery and oil pressure lights come on with first turn of the key
* Glow plug light turns on with second turn of the key
* Nothing changes when key is turned all the way to the right but there is no sound.
* Lights and indicators are working

 

[GreensvilleJay]

so... did it start and run when you bought it ?
you need to get the WSM or at least the wiring diagram !
as a quick test... take a jumper and connect starter solenoid control stud( little one) to the +12 big stud and see IF the starter spins.
If it does then 'something ' between ignition switch and the starter solenoid is 'open' (aka not connected ).
possible 'somethings' include blown fuses, chewed wires, faulty safety switches,corroded connections

 

[85Hokie]

You say the battery is "ok" - did you load test it? Take it too a local autoparts store to check?

Either you have cables from battery to start are weak or the safety switch is at fault.

Cables - remove, clean and place back - see if any difference, it does not take much to cause the amps needed to not flow well enough to crank.

IS there a clutch on tractor? IF so - is that safety switch working? ( I had one on a B7100 that would cause a no start issue)

 

[Henro]

so... did it start and run when you bought it ?
you need to get the WSM or at least the wiring diagram !
as a quick test... take a jumper and connect starter solenoid control stud( little one) to the +12 big stud and see IF the starter spins.
If it does then 'something ' between ignition switch and the starter solenoid is 'open' (aka not connected ).
possible 'somethings' include blown fuses, chewed wires, faulty safety switches,corroded connections

You can download a copy of the workshop manual from kabotabooks.com. It’s the same tractor as the B2710/2910. The 7800 is covered in the back of the workshop manual as an appendix. Electrically it’s different since it has an OPC module. The electrical diagram for the B7800 is in the appendix as well.

Jay’s suggestion is a good start. Make sure you put the range selector in neutral for extra safety. Not likely a concern with a HST but you never know.

edit: There is a clutch and it does need to be depressed for the starter to turn. good point.

 

[D2Cat]

Begin with the simple stuff, just like 85Hokie suggested. Have battery load tested at nearby auto parts store. Purchase new or at least clean existing battery cables to a shine. Clean both ends, and at the ground to the frame clean it also to a shine. Then tell us what happens when trying to start.

Any history of how long it's been setting without running, service in the past, etc makes it easier to give advise that may apply.

 

[Edke6bnl]

What I do on my b7800 on occasion when no start. I push clutch down, wiggle forward reverse, check pto off, wiggle in seat. If nothing, others have offered good ideas, load test battery, jump starter Relay, if OK need to check all the switches, seat, pto, forward reverse peddle, clutch. Good luck.

 

[Henro]

What I do on my b7800 on occasion when no start. I push clutch down, wiggle forward reverse, check pto off, wiggle in seat. If nothing, others have offered good ideas, load test battery, jump starter Relay, if OK need to check all the switches, seat, pto, forward reverse peddle, clutch. Good luck.

Good advice.

One thing that the simple test that GreensvilleJay suggested does, is it eliminates issues with the power circuit to the starter, IF the starter turns over at what seems to be a normal speed.

And if the starter does not turn over, this points to the starter and the power circuit components as being the issue. Provided of course that 12 volts is at the power lug on the starter to begin with. So a way to measure voltage at the starter lug is imperative, if the starter does not turn when a jumper is placed between the main power lug and the solenoid terminal.

I would do what Jay suggested first. Simple to accomplish. Takes almost no time, other than finding a jumper...one logical step at a time to narrow down the problem.

 

[number two]

Perhaps the travel pedal isn't centered?
Rock it back and forth gently while holding the key in the crank position.
Good Luck!

 

[jaxs]

Use your vom to check things over good.

 

[mendonsy]

Also check that the PTO lever is in the fully off position.

 

[drewzee87t]

Check - clutch switch, clutch in while starting
Put in neutral range. I don't think this model has a safety there but many kubotas do
Try to start while wiggling the treadle pedal, it has a "centered" safety
Make sure the PTO is off. My PTO safety switch gets dirt and sticks in it and has to be wiggled most of the time to get it started. I just put it to PTO, then off and hold it while starting.
I don't have a seat switch but you can jumper that to test.
After that it's battery and wiring/ground at machine frame

 

[Russell King]

And since you have just gotten a tractor please explain how you are trying to get the tractor started in several steps please. You don’t tell enough about your procedure for us to know if you are trying to start the tractor correctly. Please don’t think that I doubt your procedure but just want to know for sure what you are doing to ensure you are not missing something important.

Like this
I get onto the tractor and sit down in the seat.
I press the clutch pedal fully down.
I set the throttle to half throttle.
I turn the key on and the dash lights up.
I turn switch to glow plug position and…happens.
I turn switch to the start position and it makes no noise at all/cranks slowly/clicks and then nothing…

Have you measured the voltage on the starter solenoid wire with the key in the crank position? If not remove the (probably black with white stripe) wire from the solenoid and measure between the end of the wire and the battery ground termina when the key is on the cranking position.

 

[bshenanigan]

Thanks for all the advice.

i have had the battery tested and it is fine.

i will take a look at the solenoid just as soon as I work out what it looks like