b7800 will not turn over with the switch.

[steve broken]

I am working on my b7800 it has 85 hours on it.it will not turn over with the key switch,but with key on you can jump the starter and it will turn over and start. I felt it was a starter problem,replaced the starter ,still the same.have checked all the safty switches ,seat pto, not in gear,clutch pushed in. I did check the lead to the siliond and there is no power for the switch.starts everytime you jump the starter no problem with no one in the seat or with out the clutch being pushed in.just out of gear? anybody got a clue??thanks

 

[RjCorazza]

If there is no switched power from the key switch you will have to trace that wire and see why it's not getting 12v. My diesel mowers had similar symptom starting issues, but there was switched power to the solenoid. I ended up wiring in a relay at the solenoid so the key switch activates the relay, which in turn provides 12v power to the solenoid straight off the battery.

 

[Henro]

Like RJC said, there are a number of safety interlock contacts between the key switch and the terminal on the starter solenoid.

You either need to find the one that is bad, or need to install a relay between the string of contacts and the starter solenoid. An interposing relay takes much less power to energize than the starter solenoid. You use a contact of the new relay to apply battery voltage to the starter solenoid.

Simple and durable fix. Did this on my smaller tractor and starting issues were soon forgotten.

Edit: If in fact one of the permissive switches actually failed totally, then you will need to replace it and an interposing really will not help you.

I had the problem that required an interposing relay on my BX 2200, but never had the problem on my B 2910, which is essentially the same tractor as your B7800.

Bill

 

[JOHNTHOMAS]

The B7800 had an issue. I went thru several "fixes" till I accidently moved the foot pedal on mine and it started. Try centering the foot pedal. Several B7800 owners in the past ran into this issue.

 

[Spanner]

I am working on my b7800 it has 85 hours on it.it will not turn over with the key switch,but with key on you can jump the starter and it will turn over and start. I felt it was a starter problem,replaced the starter ,still the same.have checked all the safty switches ,seat pto, not in gear,clutch pushed in. I did check the lead to the siliond and there is no power for the switch.starts everytime you jump the starter no problem with no one in the seat or with out the clutch being pushed in.just out of gear? anybody got a clue??thanks

The relevant points from your post are:

it will not turn over with the key switch,but with key on you can jump the starter and it will turn over and start.

I felt it was a starter problem,replaced the starter ,still the same.

I did check the lead to the siliond (sic.) and there is no power for the switch

Search the forum for the multitude of other threads like this where people replace components at random with no real logical diagnostics.

Start at the battery and trace your wiring as RJC suggests. Battery voltage at key switch? Out of key switch to interlocks?? Test each interlock switch???

etc...

 

[newbury]

A B7800 (last manufactured in 2008) could be 8 to 13 years old.
How old is the battery?
I realize that checking the battery itself can be a pain, but have you had the battery load tested?
The battery on my M4700 died and would engage the solenoid but not enough. The battery would charge and reported about 14 volts. I took the battery to NAPA and they load tested and it failed, I bought a new battery, problem solved.

 

[CalG]

A B7800 (last manufactured in 2008) could be 8 to 13 years old.
How old is the battery?
I realize that checking the battery itself can be a pain, but have you had the battery load tested?
The battery on my M4700 died and would engage the solenoid but not enough. The battery would charge and reported about 14 volts. I took the battery to NAPA and they load tested and it failed, I bought a new battery, problem solved.

If the starter motors well when the terminals are jumped, the battery is likely "good enough".
There may be issues with connections etc. My guess is there is a winkey interlock switch "somewhere" that is messing up the circuit to the starter solenoid.

 

[kthompson]

I think you will find issue with a safety switch also and possibly an adjust issue. First try holding the key in the start position and carefully move the pto lever or levers to see if they are out of adjustment(that was my issue), clutch pedal and since you are in the seat to hold the key and work the clutch would assume you are testing that switch. If you do not find it that way then you have to follow the power as has been said. You would need a good helper to hold the key for you.

 

[Leejohn]

I have the seat switch bypassed. The clutch switch has always worked, but the pto one has now and then acted up. The hst. peddle gets a stick in it sometime and after it is removed has always worked. I would look more at the pto.