G1800 bogging down while mowing

[Bob01]

After mowing for a while my engine will suddenly bog down and die. After restarting it I can mow for a little while and it will die again. Sometimes just before it dies I can turn off the pto and the engine will smooth out and run again. Could this be the seat switch or is this condition pto related?

 

[zzvyb6]

Doesn't it look like a fuel filter plugged problem? When you need power you need fuel RATE. The filter or pump is limiting your fuel flow rate.

 

[jinman]

Your G1800 has two fuel filters and a fuel pump lift pump. One filter is before the pump and one is on the engine. I think folks often change the engine filter and miss the one that is behind the left rear wheel before the fuel pump. I'd change both these filters and see if the problem goes away. If not, be ready to replace the fuel pump. That's a common failure too on these older mowers. The fuel pump can be tested by removing the outlet hose and turning on the keyswitch. The pump should run and pump out diesel fuel, but the pressure is very low. If it runs and pumps, it is probably okay.

 

[Bob01]

I'm just on my second tank of diesel since the Kubota dealer serviced my fuel system. They supposedly they changed out both my fuel filters and installed a new fuel pump. The bogging down was the reason I took it to be serviced, now it has started doing it again. Today I was mowing and every once and a while when I could feel the bogging start I would disengage the pto lever and increase the speed to keep it running. It's puzzling.

 

[jinman]

I understand your frustration now. I have to believe that either air or water is getting into your system. It also could be the kill solenoid acting up. I don't mean the actual solenoid, but rather the linkage. Do you have the backup kill knob to pull? Make sure that is pushed all the way in. My kill solenoid has been removed and I only use the knob. If the linkage binds, it could be just enough out of position to cause the fuel delivery to be partially cut off. Just brainstorming here. . . .

 

[leonz]

After mowing for a while my engine will suddenly bog down and die. After restarting it I can mow for a little while and it will die again. Sometimes just before it dies I can turn off the pto and the engine will smooth out and run again. Could this be the seat switch or is this condition pto related?

The inlet screen is a likely culprit most of the time.
The injection pump creates a huge pressure gradient
which pulls the fuel in and when you stop and turn off the PTO
The fule is bouncing around and the pump works much less hard when the material is pulled off the screen by the fuel sloshing around.

 

[GPintheMitten]

Sounds like fuel filter / supply or air filter. I just replaced both because my B6200 was bogging down and it runs like a top now.

 

[Transit]

If there is a filter located in the fuel tank I would remove it and look carefully to see if the filter is clogged by diesel bugs. A filter in the tank is hard to service. Also, are the fuel lines in good shape, sometimes the inner lining collapse and blocks off the flow?

 

[Bob01]

Do you have to remove the tank to drain the fuel or can you disconnect the fuel line from the rear fuel filter and drain the tank? Or do you have to remove the body to remove the tank?

 

[leonz]

Do you have to remove the tank to drain the fuel or can you disconnect the fuel line from the rear fuel filter and drain the tank? Or do you have to remove the body to remove the tank?

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The best thing to do is empty the tank by draining it-disconnect the fuel lines
fuel line and the overflow return line and let it drain into a clean diesel can. then you can safely remove it from the tractor and disconnect the base fitting to clean the tank with a little isopropyl alcohol by pouring it into the tank, and shake the tank with the cap on pour out the alcohol let it dry then stick a vacuum wand in it to suck up any dried up junk if it does not fall out.

A second fool proof method is water and a hand full of pea gravel or alcohol and the pea gravel, I would rather see alcohol used as it will evaporate completely.

 

[Bob01]

Ok guys I have completely overhauled the entire fuel system, new lines new filters front and rear and fuel pump, drained the tank and cleaned it out, cleaned the injector pump and injectors and cleaned the fuel overflow line, checked all the safety switches and replaced, installed new air filter and installed new Interstate battery. Still have the bogging and dying problem. It's not the fuel because I use the same fuel in my other two tractors with no problems.

 

[jinman]

Wow! Have you tried running with your fuel tank cap loose enough that it will vent for sure? It would seem that you've chased through the entire fuel system and now you have to start thinking about valves and compression leakage maybe. A valve sticking could cause this or a chunk of carbon holding a valve open, but I'm grasping at staws here. You've got to be really frustrated. Mine also does it from time-to-time, but only for a few seconds and normally maybe once every 5th or 6th use of the mower.

 

[Bob01]

I get the same bogging down when I raise up off the seat when the pto is engaged, but I have replaced the seat switch. How do you wire around the seat switch??

 

[Gary Fowler]

Check the seat switch, is it normally opened or closed when pressure is on the seat. ON my old Troybuilt gasser, I just had to pull the plug. How it worked was when you took the pressure off it closed the circuit and killed the ignition by grounding it out so by unplugging the wire, it couldnt ground out. No clue to your bogging down issue. Seems like you have done everything that can be done to the fuel system, now you may want to look at the electrical for gremlins if there is any sort of electrical kill switch involved.

 

[Bob01]

I have been told by three local G1800 owners that they have experienced the same problem and now get this, all three have told me that it was a faulty fuel cap?? I don't have anything to lose so I ordered me one today. I will let you know when the cap arrives if it stops the problem.

 

[Bob01]

New fuel cap arrived Wednesday Put it on and presto, mowed leaves for three hours no bogging down,go figure...how could this be so simple? :laughing:

 

[peculiarmike]

New fuel cap arrived Wednesday Put it on and presto, mowed leaves for three hours no bogging down,go figure...how could this be so simple? :laughing:

Have the same problem with my used G1800 I bought a while back (I really like it).
Just applied a new $12.58 cap and about 20 minutes mowing later had the same problem, so the cap is not the problem on mine. It happens on level ground, on an incline, wherever.
I've serviced, maintained, repaired, rebuilt Diesels 36 years. BIG ones, in locomotives. A Diesel is a Diesel. This is a fuel problem and my next stop will be the fuel tank to see what is in there besides fuel.

 

[jinman]

You have two filters and a lift pump to consider. There is a filter before the lift pump that's located behind the left tire near the lift pump. As a minimum, I'd change both filters. I also think there may be a bad connection to the lift pump or it may not be running. When the tractor stalls, turn the ignition switch off/on and listen carefully to hear the lift pump operating or place your hand on it to make sure it's running before attempting to start the engine.

EDIT: I went back and found all the things you've done and refreshed my memory. I think there's a good chance that the ignition switch is only powering your lift pump intermittently.

 

[peculiarmike]

Not saying this is the problem. But it could be if you are not careful.
Diesel fuel will grow bacteria and fungi. It takes a bit of water, generally condensation and no more than a drop, to get it started and it goes from there. There are 27 types of bacteria that can grow in Diesel fuel. They can cause damage to steel parts and clog filters. Do a little research.
There is a range of additives out there that will keep Diesel bug from your tank. You should be using one.