B7800 won’t start

[Gto19]

My B7800 had a problem with the fuel cut off switch. You can hear it 'click' (energizing the switch) when you turn the key to the start position. If that doesn't make contact it won't 'click' and cuts off the fuel to the engine and it'll turn over but not start. This switch cost about $150 and is located by the key switch under the RPM indicator. And yes, everything else had power.
It may not be your problem though as you were able to start it by jumping it. Just make sure you hear that 'click' when you turn the key.

Yes I get the single click

 

[Jaygyver]

Well, how about a simple check, the lights only need voltage but the starter needs amps.

If you have lights and the solenoid makes noise then sometimes the battery cables at the battery can get just enough gunk to not let it pass enough amps thru to the starter.
I've had it happen on a newer car when "someone" left the lights on for a week and was in a hurry so just thru a new battery in it and off we go. Until about a week later the nothing, lights but no start, cleaned the battery cables up and never had a problem since.

Just thought I'd throw that in, good luck....

 

[AnotherBueller]

Well, how about a simple check, the lights only need voltage but the starter needs amps.

If you have lights and the solenoid makes noise then sometimes the battery cables at the battery can get just enough gunk to not let it pass enough amps thru to the starter.
I've had it happen on a newer car when "someone" left the lights on for a week and was in a hurry so just thru a new battery in it and off we go. Until about a week later the nothing, lights but no start, cleaned the battery cables up and never had a problem since.

Just thought I'd throw that in, good luck....

My guess is to check the cables for corrosion and tightness.
There is a thread about this very issue somewhere. I have difficulty finding them.

 

[bgr]

On my Kubota, The small spade terminal on the wire from the ignition switch to the small terminal in the starter solenoid gets a bit of corrosion on it and I get a no start/no sound when I turn the key. I just take that wire off the terminal and put it back and wiggle it to make a clean contact. I have done that for 20 years and never had to do anything else. Something easy for you to try before you do more diagnosis.. My starter is Hitachi, I believe the same brand as yours. Problem usually happens after the tractor has not run for a month or two. If you put a test light on the wire at that terminal and the light lights when you turn the key, try cleaning the spade terminal. if the starter works when you jump a direct source of 12v. to the terminal, you can put on a booster solenoid for about $15. I have not had to do that yet.

 

[Gto19]

Fixed guys !
Bad voltage regulator underneath the dash . 50 dollar part on eBay. 10 minuteto fix , but took me two weeks to figure out ..at least I didn’t pay someone to fix it !

 

[SPYDERLK]

Hey guys
I have a 150 hour b7800 tractor that is a garage queen . I mainly use it to mow my field. I turned it off and now it won’t crank . Lights all come on though . I checked all the safety switches except the clutch safety switch because I don’t know how to get to it . I see the white connector though . I can easily start the tractor with a long jumper wire I made to go to the positive side of the battery to the starter .It will turn off with the key . Any help before I call a mechanic?


I’ve also tried rocking the forward reverse pedal to its sweet spot with no luck

Fixed guys !
Bad voltage regulator underneath the dash . 50 dollar part on eBay. 10 minuteto fix , but took me two weeks to figure out ..at least I didn’t pay someone to fix it !

So the battery was dead??!

 

[Gto19]

So the battery was dead??!

Nope ! Battery was fine . I did notice the battery indicator light on the dash was not coming on like it used to when I turned the key to the on position.

 

[SPYDERLK]

Normally a voltage regulator governs battery charging. I wonder what the component you replaced actually does.

 

[Gto19]

Normally a voltage regulator governs battery charging. I wonder what the component you replaced actually does.

 

[Gto19]

Voltage regulator

 

[SPYDERLK]

Voltage regulator

Yeah, that governs charging ... and must interface some other way that that affects the "start" circuitry.

 

[Gto19]

Normally a voltage regulator governs battery charging. I wonder what the component you replaced actually does.

Maybe it has some safety deal built into it

Yeah, that governs charging ... and must interface some other way that that affects the "start" circuitry.

yes your exactly right . Someone on the Kubota face book page had the exact problem I did so I gave it a shot and bought the part . And if that didn’t fix it I was going to buy a new ignition switch .

 

[SPYDERLK]

Maybe it has some safety deal built into it

yes your exactly right . Someone on the Kubota face book page had the exact problem I did so I gave it a shot and bought the part . And if that didn’t fix it I was going to buy a new ignition switch .

Six leads! At least 2 more than necessary for a simple regulation function. ... Interesting sleeper problem!

 

[CH4Ohio]

Maybe it has some safety deal built into it

yes your exactly right . Someone on the Kubota face book page had the exact problem I did so I gave it a shot and bought the part . And if that didn’t fix it I was going to buy a new ignition switch .

Glad you figured it out.

Keep an eye on that new part. Mine wasn't charging so I ordered a voltage regulator off Amazon. Looked perfect. Identical. Modular plug and wires were identical. Mine got hot and went up in smoke while I was pulling a disc about a month later. Good thing it put out enough smoke and smell that I noticed it -- and good thing I was close enough to the garage to grab a screwdriver and pop the dash off enough to splash some water in there. It was just starting to melt down when I got to it and unplugged it and doused it.

Ended up buying an OEM Kubota part and it's still working fine after about 6 years. Maybe I just got a bad one, but if you notice a funny smell . . . don't ignore it.

By the way, my battery light stayed on all the time and the battery wouldn't charge using the on-board dynamo. Seems my symptoms were different than what you experienced.