how do you disconnect a gas solenoid from a kubota b7800? the tractor runs fine untill you press the gas and i am trying to find out if it is a fuel delivery problem or an electrical problem and i heard if you disconnect the solenoid then you can run the tractor and if it is a bad safety switch or something you'll know because the tractor will run fine
gas solenoid
- Thread starter loganvaulter
- Start date
im sorry i forgot the most important part i said it runs fine till you press the gas. once you press the gas so far it shuts down unless you let up on the gas and it also shuts down when you engage any pto.
freewheel3
Active member
Equipment
MX5000DT LA852, BX1800D, B6000DT, B6200HSTD, B7100HSTD, L185, T1700HX, ZD1211
I don't know if a B7800 even has a fuel shut off solenoid, but regardless, it sounds like a fuel starvation issue. Lots of times a diesel engine will idle just fine but die or run rough as soon as you place any load on it (such as engaging pto) or try to increase the RPM.
When was the last time you changed the fuel filter(s)?
When was the last time you changed the fuel filter(s)?
Yes it has one. Ive pulled the wires how and dont get a click with the key. It has ti have one that is how the tractor shuts off when you turn the key.as for the filter I dont know. Its not my tractor I'm working on it for someone . It has not been kept well the seat is half falling off thats why I think a safety swich may he broken but it could be a fuel problem so befoore I go changing filters and bleeding fuel lines idw like to make sure it is a fuel problem and not a bad switch. I heard if you take off the soleniod then the it wolnt shut off if its a switch . An easy way to check if its a fuel problem or not
freewheel3
Active member
Equipment
MX5000DT LA852, BX1800D, B6000DT, B6200HSTD, B7100HSTD, L185, T1700HX, ZD1211
You can't run it without having the solenoid in place or you'll have fuel leaking as soon as you turn the key on. But you can test the operation of the solenoid simply by:
1. Shut off fuel petcock.
2. Disconnect wires to the solenoid and unscrew it from pump.
3. Reconnect wires and ground the solenoid to engine block.
4. Turn the key to "On" and see if the plunger retracts.
If it retracts then its functioning as it should. When solenoids fail, they are usually dead once and for all, not intermittent as the symptoms you've described. That's why I think its some other kind of fuel delivery issue.
i agree that is is probably fuel. but i had heard that if a safety switch on the seat goes bad it can shut off the tractor of course by activating the solenoid , i believe the solenoid its self is fine. u just wonder if it is not being triggered when its not suppose to . and also can you tell me where the second filter is. i am not 100% and dont want to take off things that aren't meant to be taken off.
freewheel3
Active member
Equipment
MX5000DT LA852, BX1800D, B6000DT, B6200HSTD, B7100HSTD, L185, T1700HX, ZD1211
OK, if you think the solenoid is fine, you can disconnect the power wire to it and then run a separate power wire from the battery to it. This will isolate it from any of the shut downs tripping it closed. Then try running the tractor and see if the problem persists. If the problem disappears then you know that it is one of the safety switches shutting it down and you will have to bypass them one at a time until you find the culprit. If the problem still persists then you know it is something else.
According to the parts diagram for a B7800 there is only one canister type fuel filter.
I would still be inclined to just change the filter first and see if that solves the problem since its quick, cheap, simple and probably wouldn't hurt since you don't know when it was last done.
When the tractor quits, does it just die same as if you shut the key off? Or does it kind of stumble and slowly die?
Just the same as if you turn off the key. Once you press the gas down so far it shuts off but if you let up in time it will stay running. Ive also been told that a fuel line may he sucking air through a pin hole. I dont know if thats possible too but thank you for the answer about the soleniod that is just the answer I needed.how to bypass the switches
and also one reason why i question weather its fuel is because in high gear i can go about 2 mph before it dies. in low i can barely get the tires moving before it dies. but it seems i press the gas the same amount. i know it is putting out more torque in low but does this really put that much more load on the engine at such a slower speed , if it was gas it would shut off under load and i may be wrong but it seems like crawling in low gear is less load then 2 mph in high
rednecklimo85
New member
Equipment
78 B6100E(brush hog, boxblade, snowplow) 85 B7200DT(loader and backhoe)
Unless there's something I'm missing on this series, if you had a bad safety switch it shouldn't run at all. A seat switch for example is either make contact or not, its not gonna care about throttle position. To me there's def a fuel problem somewere. A partially Clogged fuel filter, crap in the tank, etc. It'll support a certain amount of fuel demand and then it "leans out" and dies.
In fact IIRC another member just went thru the same symptoms and found a clogged outlet in the tank.
In fact IIRC another member just went thru the same symptoms and found a clogged outlet in the tank.
freewheel3
Active member
Equipment
MX5000DT LA852, BX1800D, B6000DT, B6200HSTD, B7100HSTD, L185, T1700HX, ZD1211
Hmm, maybe there is some kind of short or something in the solenoid circuit. When you say "press the gas" I'm assuming you mean the accelerator pedal operated by your foot. Maybe try just using the hand throttle in case the foot throttle linkage is causing some kind of electrical issue that is causing the tractor to quit. Have a good look at all your wiring to the safety switches, see if there are any bare or broken wires and make sure all connections are tight. Also check all of your ground connections.
This one is starting to baffle me. But I'm still thinking you should change the fuel filter first and eliminate that as a cause.
This one is starting to baffle me. But I'm still thinking you should change the fuel filter first and eliminate that as a cause.
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the only way to make is go it the gas pedal the hand throttle is just for rpm is is not clutch driven but that doesn't matter . i found the problem, i was messing with the solenoid trying to by pass it and it worked. come to find out somehow the seat safety switch was not being depressed by the seat. just glued a piece of wood to the bottom of seat so it makes contact and it runs like a champ. i am still replacing the filter just because it probably needs it. such a simple fix for what a pain this has been lol . redneck, the way this safety switch works is you can get up and all and you can press the accelerator down so far. i assume there is a sensor on the peddle that once it reaches a certain point , if your not on to seat, shuts the tractor down. this is really nice when your trying to hook something up and your off the tractor and have to back it up an inch. instead of getting way up on the tractor backing up and getting back down. you can just stand there and press the gas a little and your good to go. this is a life savor when your hooking and unhooking things a lot.
freewheel3
Active member
Equipment
MX5000DT LA852, BX1800D, B6000DT, B6200HSTD, B7100HSTD, L185, T1700HX, ZD1211
Glad to hear you got it figured out. By the way, the pedal you've been mentioning isn't a gas pedal, its your hydrostatic drive engagement pedal.
Ok thanks for letting me know I'm not an expert at this lol this was my first time messing with a diesel I knew the tractor had hst just dident know what that was