855 starts rough sometimes

[TractorGuy]

My 855 starts and goes rump rump rump and won't smooth out or accelerate sometimes. When it starts and runs bad you can't turn the key off and get it to shut down without pulling the throttle to rest. Usually I can shut it off and restart and it starts and runs okay. Today it did this 4 times in a row so I let it sit a while and restarted and it was okay then. When it is running normal you can pull the throttle to rest and it idles down and keeps running smooth until you turn the key off as it should. The filters are clean and recent and no signs of water or trash in the fuel.

Any ideas?

 

[texasranger556]

Sounds like a fuel problem. Is the shut off solenoid opening and closing all the way?

 

[TractorGuy]

That is a good thought. Could be the shut off solenoid sticking part way open. When it starts up running rough, turning the switch off doesn't kill it. I have to pull the throttle back to get it shut down. Pulling the throttle back will shut it down with key on or off though.

When it starts and runs as it should which is 99% of the time it shuts off normal but I always idle it down before turning the switch off.

 

[Rara Avis]

Well..here is the following check lists to run down...

If engine will not start or starts hard...
1. Check fuel quality.
2. Test fuel transfer pump output.
3. Check fuel shutoff solenoid for binding and adjust, if necessary.
4. Test cold start aid controller.
5. Test engine compression.
6. Check and adjust valve clearance.
7. Imprper air restriction indicator installed.
8. Test injection nozzles.
9. Check injectionpump timing and check if plunger is stuck.
10. Remove fuel injection pump and have it tested.
11. Check cranking speed.
12. Check for proper oil viscosity.
13. Air heater control functioning improperly.
14. Improper cylinder head torque, gasket leaking or head warped...

If the engine is missing...
1. Check fuel quality.
2. Replace fuel filter and air cleaner.
3. Test fuel transfer pump.
4. Bleed fuel system.
5. Check injection nozzle return line for restriction.
6. Test injection nozzles.
7. Check injection pump timing.
8 Check thermostat.
9. Test engine compression.
10. Check and adjust valve clearance.

Good luck...

PS get yourself a copy of the Tech Manual TM1360

 

[jd110]

My first thought is sticking injection pump. How fresh is the fuel? Have you tried any fuel additives? I would drain fuel if not fresh and then add fresh fuel along with a good fuel conditioner/algae killer such as Stabil Diesel Biocide.

 

[TractorGuy]

Fuel is fresh and clean. I run off road diesel and treat it with Killum Biocide and Stanadyne lubricity additives. I go through 100 gallons every 3 or 4 months. I check for water and sludge every month when I do my generator tests. So far I have never had any water or sludge accumulation. I did find some black stuff in the bottom of the 855 tank before setting up the storage drums but it was obviously below the pickup tube. There was no black stuff in the filter. When I cleaned that out I changed the fuel filter on the tractor and added a small engine filter in the supply line up top so I can see the fuel easily without removing the side panel.

My thoughts are it must be something sticking since it is very intermittent. It has never failed to eventually start and run correctly. Yesterday was the first time I ever had to shut it down and restart more than twice to get it back to proper operation. It will run properly as long as you need it when it starts and runs proper. I ran it a half day straight after getting past the initial start up yesterday. This is just an intermittent startup problem.

My plan it to locate the fuel shut off solenoid and be prepared to bang on it the next time it messes up. I might go ahead and check voltage to it on start up to make sure there isn't a voltage drop.

 

[pmsmechanic]

Is there a leak in the fuel line from the tank to the lift pump?

 

[thepumpguysc]

If the engine shuts down w/ the key switch, it has an electric solenoid on it.
If it shuts down w/ a pull cable it doesn't..
The solenoid is normally located to the left or right if the injection pump.
To diagnose the problem, just remove the shut down solenoid completely from the system.
That'll tell you REAL QUICK if the sol. is sticking & preventing the first start of the day.
Normally all they are is a plunger, spring & a magnet.. take the plunger out & clean it & the bore, in the magnet.
IF it turns out to be the pump & or the injectors, I can help w/ that.. Good luck..

 

[texasranger556]

The 55 series have an electronic solenoid for fuel shutoff.

 

[larboc]

The 55 series have an electronic solenoid for fuel shutoff.

And it's tied into the starter, any chance you have scuffed wires in there?