7800 has no power and won't run!

iamhistory

New member
Ok fellas......I need a hand if you wouldn't mind.

I have a 4 year old B7800 with about 350 hours on it. It has been a great machine and I have taken care of it. Yesterday I started it up, it ran for about 15 minutes just like normal. I was trying to scoop some dirt to put in a raised garden bed and the power started to go away, the idle went way down and I couldn't even make it back to the garage.

Previous to yesterday, it ran fine with no problems or even a hint of this behavior. Today it would hardly start up. I cleaned the fuel filter, checked the lines, cleaned the air cleaner, etc. and again it ran fine for about 15 minutes, good power just like everyday normal running. I actually dug in the dirt, got a scoop and dumped it. Went back for a second and the engine started conking out again. There is no power, it idles high and low, high and low but not enough power to run the tractor and eventually it stalls out. It is hard to start and if it does start and the engine builds up any sort of idle, it is rough and puts out a lot of white smoke.

I don't expect my fuel to be bad, it is not old and I have power diesel added to it. Unless someone tampered with it (odds are small) or there is something else like a injector nozzle problem I wouldn't know what else it could be.......I don't have the expertise to narrow it down. Can you guys help me out?

I took two videos of the engine running in case anyone would like to see them to hear the engine and see the smoke.
 

OhioTC18

Well-known member
Gold Site Supporter
Check your fuel tank and see if it's collapsing from a vacuum form a poorly vented cap. Also check the interior of the tank with a flashlight for settled debris clogging the fuel outlet.
 

Kanook

Active member
Sounds like fuel delivery..agree with TC18..loosen your fuel cap..Also you say you cleaned your fuel filter, if it's the same as on my B1700 , the paper element slides over a tube mesh strainer...I'd look for non venting, clogged tank outlet, clogged filter etc and replace the paper element..Good luck and let us know the result.
 

iamhistory

New member
Was about to put a new air filter on anyway.......so I'll just replace both. Am gonna empty the tank also and take a look.

We'll see what happens then.

Thanks for the input guys. I started with the simple stuff and figured it would be something small. I was afraid it wasn't but you have put my mind at ease.

I'll let you know how it goes.
 

drummer

New member
power loss

My B7800 had a similar problem. The cap of the fuel filter cartridge has a flapper in it that stops fuel flow when you remove the plastic filter container. That valve was sticking. I drilled it out. Now when I change the filter, I put a vise grip on the fuel line.
 

EastTexFrank

Senior Member
Gold Site Supporter
Check your fuel tank and see if it's collapsing from a vacuum form a poorly vented cap. Also check the interior of the tank with a flashlight for settled debris clogging the fuel outlet.

That would be a good place to start.

When I had a problem like that it was caused by a small leaf that has somehow fallen in to the fuel tank. Took me ages to figure out what it was and get it out of there.

I also read on one of the tractor boards that someone had a similar problem caused when he had left the cap off and a bee or a wasp had flown in to his tank, died and would occasionally lodge in the outlet line from the fuel tank, starving the engine.
 

iamhistory

New member
Update FYI:

I installed a new air cleaner and new fuel filter. I checked the lines for blockages and didn't find any that were apparent. I drained the tank to try and get a look for debris. I couldn't see anything but it was pretty hard trying to look inside with a light. I blew out the air dam in case it was blocked...it wasn't.

Still not fixed. I ran the tractor today first thing and it ran like brand new. I used the belly mower a little, moved dirt, etc. After about ten minutes.....as has been the case, it starts acting up and I have to limp it back to the garage. Then it barely starts and will pretty much only idle. No power at all. It does the same thing with the cap on tight, loose or off. The tank doesn't appear to be collapsing. When I drained the tank the fuel flowed very well out of the line.

I only have 347.9 hours on this thing and this just happened out of nowhere. I'm puzzled.
 

drummer

New member
My B7800 non-starting problem was a broken wire between the key and the starter. Local mechanic ran a wire direct from key to starter. Works fine! All safety switches still work. Cost me about 1/4 of what the Kubota dealer would charge.

happy again!
 

Kanook

Active member
I've had almost identical problems with 2 gasoline engines in the past. After engine warm up to operating temperature, a loss of power would develope. Allowing them to cool down and they would resume satisfactory operation until back up to operating temperature. Both engines needed valve jobs. I am in no way a diesel engine mechanic so I present this only as info as to my experience with gas engines that develope a los of compression once at operating temperature. I seriously doubt a Kubota diesel would have such a condition with so few hours.

I own 3 Kubota diesel machines and am keenly interested in the source of your problem. ( I may run into the same someday)

Still sounds like a fuel delivery issue ....wish I could be more helpful.

Good luck and keep us informed.
 

SpudHauler

Active member
Site Supporter
You might try running a new piece of fuel line direct from the tank to the fuel injector pump as a test. Or if you have a gas (fuel) tank you could use as a test with it's line direct to the pump and by-pass your whole system.

Bypassing the filter assembly with a straight piece of pipe and join the two hose ends.

I had a 90 degree kink in a fuel line that acted like your explanation.

Although it would stop and then restart okay.

But after 10 min or less would run out of power each time.

Perhaps by-passing the filter will reveal the problem.
 

iamhistory

New member
I finally got it running. I emptied the tank, again, blew out the lines, again, bled the injectors and changed the fuel.

Started up and ran like a champ.

I had done all of the things I've been posting (new filters, checked for debris, etc.) and trying posters' suggestions to no avail. I bled the injectors and the tractor ran better but not correctly at all. I dumped out the fuel I was using which was fairly fresh and got new.

I started her up and she's been running fine since.

Thanks for all the input.
 

Doc

Admin
Staff member
Gold Site Supporter
Glad you got her fixed ....just wish there was a more obvious solution to the problem. At this point you are not sure what fixed it are you? Do you suspect it was a fuel issue and the fresh fuel did the trick? :confused:
 
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