# Laboring engine Bobcat CT120



## hoho223 (Jul 1, 2016)

Bobcat CT120, 255 hrs, Kioti 3 cyl diesel, front loader. Previous repair: Replaced fuel shutoff solenoid (electrical problem)
After previous repair the tractor was used and worked but began laboring to the point of shutdown when under load. The unit would rev back up after relieving it of the load which in the main case was just moving forward. Unit was returned to bobcat and the following was done: replace fuel filter, flush fuel line, check fluid levels, readjust fuel shutoff solenoid linkage, replace fuel shutoff mechanism as much as is accessible from outside the engine and a visit from the factory rep. The diagnosis was the fuel shutoff was not allowing the full flow of fuel to go to the fuel pump. The tractor was tested and judged repaired and I brought it home.
After using it today for awhile the same situation started to occur..laboring under load to the point of shutdown. 

The engine is acting as if fuel starved. Could there be a hydraulic problem or is it strictly a fuel problem?
Thank you for your advice and knowledge.


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## catfishjohn (Jun 11, 2016)

Sounds like the fuel system has been gone over perity good,, but the fuel shut off may be still the problem or your hyd. filter may need to be changed. Even though the soleniod was replaced don't mean
it can't be bad. Check the wire to it for loose connection. You Can make a hot jump wire and see if the soleniod makes a clickin sound it is good'. Keep us posted what you find, that lets us all learn a little more. and welcome to the forum. Chaddar71 had the same problem and found a faulty (intermettent ignition switch).


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## hoho223 (Jul 1, 2016)

Fuel shutoff solenoid is good. Functions appropriately. I will try the filter change.
Regarding comment on another owners problem....sounds like his was a shutoff problem. Mine is a dogging engine problem, in particular under load.


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## hoho223 (Jul 1, 2016)

Also appreciate the viewings of this thread but please throw in your 2 cents. All thoughts appreciated.


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## sixbales (May 18, 2011)

Hey HoHo,

A "bogging" diesel is either having a fuel supply issue, OR it may be an unknown load entering the picture. 

Try this first: With the engine running, crack open the injector connections at the injectors one at a time, allow any trapped air to bleed out, and then tighten and go to the next injector. I have to do this to my neighbor's tractor periodically...it gets into a funk....loses power.
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A Bobcat probably has a fuel lift pump as opposed to gravity flow?? Can you check that it provides ample fuel to the filters. There may be plugged fuel screens in the system. My Ford tractor has a fuel screen in the tank, a fuel screen in top of the sediment bowl, a fuel screen in the lift pump inlet, and it also has a very small fuel filter in the inlet of the injection pump. 

Have you changed the fuel filters lately? 
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Regarding an unknown load, does it pull in one direction, requiring maneuvering in the opposite direction to keep it going straight?


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## hoho223 (Jul 1, 2016)

Will check these things on Tuesday.


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## pogobill (Jan 31, 2012)

Hopefully it's not a hydraulic problem. Maybe a sticky valve causing the hydraulics to overload and bog the engine down!?! When it bogs down, have you tried working all the hydraulics to see if something relieves your problem?


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## hoho223 (Jul 1, 2016)

Regarding maneuvering and pulling. Nothing unusual happens when I turn except that this is when the engine bogs down as it does when I'm going up an incline or if I try to use the bucket in a working way. If I am on level ground it will also bog down when I try to move forward at max speed. 
I have not purposely tried to raise the bucket when moving or turning. I will on Tuesday


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## hoho223 (Jul 1, 2016)

!. Bleeding injectors no help.
2. Operating bucket does not provide relief and in fact provides more load causing engine to labor more.
3. I don't have spare filters for hydrostatic or hydraulic change-out.
4. As mentioned there is no pulling to one side or the other when maneuvering


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## hoho223 (Jul 1, 2016)

Also regarding fuel flow. This tractor has a fuel pump on engine which I assume is gravity fed from tank which is elevated behind tractor seat. It also has a fuel return line which I assume is standard on these diesel engines.


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## pogobill (Jan 31, 2012)

Yes, a return line is standard on a diesel. If your tractor bogs down when operating the bucket, it seems that there in lies some of your problem.
Steer it left, then right, raise the boom and then lower it. Roll the bucket up and then dump it down... all to their limits. try to determine what function is causing it to bog down. Almost sounds like a relief in the hydraulic system is not working as it should. Should have your dealer check hydraulic pressures to rule out any problems hydraulic system. Perhaps they already did this when they were trouble shooting your problem in the first place.
Addition to my comment:
I had a stuck control lever for the rotation on my snowblower chute and the tractor was bogging right down. Couldn't figure it out til I operated the bottomed out lever and all was well. Also could the tractor be in second gear and in high range? That'll knock the heck out of your performance. Just throwing things out there!


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## hoho223 (Jul 1, 2016)

Returned to dealer again. Leaning more towards a fuel starvation problem because when pushing up throttle from idle it does not rev up properly. Slow response. 
To throw a little monkey wrench into the process, when turning (hydraulic load) going forward the engine labors. While going in reverse and turning, it doesn't.
Re: gears and high range. It is a hydrostatic drive....forward and reverse.


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## pogobill (Jan 31, 2012)

hoho223 said:


> Returned to dealer again. Leaning more towards a fuel starvation problem because when pushing up throttle from idle it does not rev up properly. Slow response.
> To throw a little monkey wrench into the process, when turning (hydraulic load) going forward the engine labors. While going in reverse and turning, it doesn't.
> Re: gears and high range. It is a hydrostatic drive....forward and reverse.


Well, I sure hope the dealer finds the problem. Maybe it's sucking air at the injector pump or the like.
My tractor is a hydro-static drive as well. 2 speeds with high and low range in each speed so basically 4 speeds in forward and reverse.
Let us know if you get it sorted!
Cheers


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## gaspump (May 12, 2013)

*Bobcat engine laboring*

IfI may jump in here, sounds like you have been around the mulberry bush with this problem! I have found that rather than guess what is happening, one needs to put a good pressure gauge in fuel line, after fuel filter and lift pump but before injection pump and "T-d" in line. Put an inches of water gauge after air cleaner but before engine, next put pressure guage( high pressure, about 5000 psi) after each hyd pump, but before any valves. Start engine, and at idle fuel pressure must be high side of specs, air gauge must be almost "0", hyd gauge should be around 500 psi or lower.
Rev engine to high idle, fuel pressure has to be high side of specs, air should be very low, hyd still should be under 500 psi. Start putting load on, raise boom and stall, or move machine, one has to be very careful and remember safety doing this, no one else around unit is best. Fuel pressure under load must be near high side of specs, air should be under 7 in water, hyd will be near relief valve setting. (Remember one pump, one gauge, two pumps two gauges etc)
Record each gauge reading at each test point, idle, full rpm and full load.
This will tell where problem is. I am surprised your dealer didn't do this.
Hope this helps, let us know results, pls


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## gaspump (May 12, 2013)

*Bob cat engine labouring*

Forgot to mention, fuel pressure should be around 35 psi, but check specs.:


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## hoho223 (Jul 1, 2016)

Gaspump:

District service manager now involved. I will make sure he sees this. Do not know if they have done it or not.


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## gaspump (May 12, 2013)

*Bogging engine*

Hi, ---they probably haven't done this or they would be able to tell you where problem is and have it repaired by now. Thinking ahead, if they haven't done this yet, they need to put someone on this repair that understands what the gauges are telling them.


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## hoho223 (Jul 1, 2016)

Returned to dealer 7/6....calling dealer for update today seeing as they haven't called me. Will post results later.


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## hoho223 (Jul 1, 2016)

Call to dealer:
The governor is the presumed problem and the unit should be ready this PM after testing.


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## gaspump (May 12, 2013)

How did you make out at the dealer?


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## hoho223 (Jul 1, 2016)

Sorry for the delay. Picked up tractor and they said they repaired the governor. I don't know where they are on any engine but this one is internal. So far working like its old self.


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## hoho223 (Jul 1, 2016)

Sorry for the delay. Picked up the unit and hey said they repaired the governor. Don't know where a governor is on any engine but this,one is internal. Performs lie its old self again.


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