Power Loss????...it's not the fuel filter

[docmx]

I have a M4900 with 370 hrs. The last few times out, it has been losing power after running for a couple of hours. I cleaned the fuel filter and had the same problem, so I replaced the fuel filter with a brand new one and still have the same problem. It will be running just fine and then abruptly drop rpm and run rough when I try to accelerate, particularly in higher gears. I have cleaned the air filters as well. If I let it sit over night and start it the next day, it will run fine for about 2 hours then abruptly loses power. Any ideas????

 

[TripleR]

Our Massey Ferguson 375 did this and it turned out here was trash in the fuel line. The tank had to be taken off and cleaned was well as the fuel lines. Apparently we go some bad fuel.

 

[RayCo]

Does this tractor have two fuel filters?

 

[jlsmith]

Have you noticed any black slimy stuff in the fuel or filter. We had a case of black algea not to long ago and it made out tractor do exactly what yours are doing.

 

[docmx]

It has one filter set inside a clear plastic screw on container. I haven't notice in slime....someone suggested water in the fuel, but if that were the case why does it run perfectly for 2 hrs before power loss occurs. Local Kabota service department suggested it may be some trash in the fuel tank that takes a while to work its way down and clogs the fuel line. But again, why does it run fine after it sits overnight???

 

[dex3361]

Does your tractor have the bleed valve above the fuel filter on the injector pump. It has a round knob that is about 3/4" around. Make sure the valve is turned clockwise (to close). If this valve is left open it can act as you describe. This is the knob that is used to bleed the fuel system.

 

[docmx]

It does not have a bleed valve.

 

[leonz]

It has one filter set inside a clear plastic screw on container. I haven't notice in slime....someone suggested water in the fuel, but if that were the case why does it run perfectly for 2 hrs before power loss occurs. The local Kubota service department suggested it may be some trash in the fuel tank that takes a while to work its way down and clogs the fuel line. But again, why does it run fine after it sits overnight???

The junk or trash has floated to the top
or settled away from the inlet screen
and is no longer being pulled down into the
primary screen of the tank by the pressure
gradient created by the injection pump.


Any algae will collect on the interior walls
of the tank and be hard to see unless
you wash the tank out.


The water issue is always a constant problem
with surface or buried storage.


Once you start your diesel engine the excess fuel
that is not pulled into the combustion chambers is
pushed back into the fuel rail, then back to tank
and is agitating the entire tank of fuel and reheating
the cold fuel as well.


Any water settling to the bottom of the tank after
shut down or during operation simply is pulled into
the fuel system with the fuel and then either boiled
by the combustion and evaporated or pumped back
to the tank with the fuel that is not consumed.


I constantly mention the Racor 1100 Diesel
fuel filter uses the pressure gradient created by
the engines injection pump to pull the fuel through
the stationary vanes of the filter which spins the
fuel into the bowl prior to final filtration.


The vanes create a centrifigal action and
allow the water to fall away to the bottom
of the clear bowl as it spins through and
disposes of the dirt and and debris in
the same manner.


The Racor units have a manual drain valve
which allows you to drain the water and dirt
out of the filter system when you wish to do so
and the clear bottom bowl allows easy inspection
of the sediment and water level in the base.


The Racor 1100 fuel filter can be ordered with a
thermostat controled heatiing element to heat
the diesel fuel as well.


For what its worth it does not take much water
at all to ruin a diesel fuel filter; this is the greatest
benefit of the racor filter is it eliminates the water
from the fuel stream at all times.

 

[docmx]

Why would it run perfectly for 2 hrs. before power loss. If it was water in the fuel, wouldn't it run rough constantly?

 

[docmx]

After mowing for about 2 hrs. it loss power and rpm fell. I limped my way back to the trailer. Loaded up and went home. About 45 minutes. When I got home I started it and it ran fine while I was working around the home for about 1 hr. It never hesitated or loss power, but I bet if I stayed at it for another hour it would have given me fits. Should I drain the tank? If so, is that best done by disconnecting the fuel line going to the filter?