B7800 stopped running

[Kart17]

All,

Was working with my B7800 when it suddenly shuts off. Checked fuel, replaced fuel filter, bleed system, nothing comming out at injector supply tubes. Fuel is getting pumped everwhere but to the injectors (overflow lines). My thought is fuel stop solenoid. Fuse is ok, will check seat switches for opens in the morning. Anyone have any other possible items I should check? Anyone know how to bybass the run loop on this solenoid? Anyone have a part number for the solenoid.

Thanks in advance,

Steve

 

[ChuckinNH]

There are safety switches on the seat, pto, and possibly the clutch. It sure sounds like one of them isn't functioning. Make sure your pto lever didn't get bumped off just a bit.

 

[Kart17]

Thanks for the reply!

Checked emergency switch on PTO, Clutch, HST and had my big posterior in the seat. Not sure if the seat switch is ok but when I moved the PTO to 兎ngaged no crank, clutch not engaged, no crank, HST peddle up or back, no crank

 

[JOHNTHOMAS]

Had a B7800. I know you said you checked HST but sit on seat one more time and rock HST pedal while trying to start it. That's the common problem with the B7800. If that doesn't work then I don't know but guess you have to start checking electrical path to starter from switch.

 

[pdowling1]

Note that the OP said it stopped running, not that it won't start. That eliminates the safety switches, except the seat switch. He may be on the right track to look iat the fuel cutoff solenoid.

 

[kevinj]

Note that the OP said it stopped running, not that it won't start. That eliminates the safety switches, except the seat switch. He may be on the right track to look iat the fuel cutoff solenoid.

He has also said that it will not crank.

 

[pdowling1]

Look again, he said no fuel to the injectors, that implies it is cranking, not starting.

Oops, I just reread his second post. Now I am confused!

 

[kevinj]

Look again, he said no fuel to the injectors, that implies it is cranking, not starting.

Oops, I just reread his second post. Now I am confused!

It is probably in the safety system somewhere as it has stopped and will not crank. On some machines that can be just a fuse. It certainly needs some proper troubleshooting applied.

 

[Kart17]

Sorry for confusing everyone with my second reply. It will crank, just won't start. Soooo here has been my attempts to this point:

1. Drained tank, replaced fuel filter.

2. Bypassed ALMOST ALL safety switch items EXCEPT the clutch pedal. This included, both PTO switches, seat switches, HST switch. It would crank but not start and no fuel to the injectors however, fuel pumped through overflow back into tank just fine. Checked all switches for resistance with multimeter.

3. Wired (soldered) a lead from the fuse protected side of the fuel cutoff solenoid directly to the largest of the 2 white wires feeding the connector to the fuel cutoff solenoid. Did not cut the wire, just stripped insulation, wrapped new wire around exposed wire and soldered to exposed wire. Installed fuse heard the solenoid click and she fired right up!!!!!

4. Pulled 30amp fuel cutoff solenoid fuse, removed all the safety bypasses,
I installed a quick disconnect for my "creative" fuel solenoid power solution reinstalled fuse, fired right up! Also rigged up a pull wire from the manual fuel shutoff on injector pump to kill the motor just like the good ole tractors.


Ran the tractor for about 1 hour, no issues, but not really doing anything.

With the tractor still not having been shut off, went to get some hay and straw. Had the tractor in "H" going over to get the hay, loaded 4 bales into bucket and started backing up and she died! Looked around, blew the 30 amp fuse. Replaced the fuse, it started right up, drove to the truck to get bale of straw, loaded straw, tried to backup, it died again. You guessed it, fuse again.

Replaced fuse, tried to start, heard a click, no lights anywhere, not instrument cluster, head lights, emergency flashers. Check 30amp by alternator(dynamo),and it had blown, pulled fuel cutoff solenoid fuse, replaced main battery fuse, reinstalled fuel cutoff solenoid fuse. Started it backup.

Decided to put it on the trailer in case I can't get it fixed I can haul it to a dealer. While backing up, was in 2 wheel drive and it was raining, tires spun on wet trailer deck and it died. Yep, fuel cutoff solenoid fuse popped again. Replaced fuse, started backup, put in 4 wheel, turned around and drove nose first onto trailer.


This is where I am at, I believe I have one of two issues:

1. Bad fuel cutoff solenoid.
2. Electrical short in a wire or safety switch somewhere or some other **** safety item.

Any help at all would be appreciated! I am at a loss from this point if it is not item 1 above. Does anyone have an electrical schematic for a B7800??

Thanks again to everyone!

Steve

 

[Fjord]

You've probably thought of this, but is there any chance that there's a wire rubbing on your pedal or linkage that only rubs when you go to back up? Or something like a stick in the linkage that pokes the wiring which is nowhere near the linkage when you back up. It just seems like your problem always occurs when you back up. I also have a B7800 so I'm interested in the outcome in case the same thing ever happens to mine. Keep us posted.