Changed out fuel filter and now tractor won't start

[Csawy31]

I was having some intermittent power loss lately where the engine would just rev down and stumble along for a few seconds and then regain power.
I changed out the fuel filter and cleaned the fuel strainer.
Pumped up the filter till it was hard to push the pump, filled the fuel strainer and then started it.
It ran for a minute, then began to stumble. I was able to keep it running and started to drive it back to the shed when it stumbled again and then quit.
I have not been able to restart it since.
It will crank fine but no start.
I opened the fuel cap in case that was the issue but no go.
I am stumped [being relatively diesel ignorant].
This is a real problem with a winter storm on the horizon.
Any help is greatly appreciated

I was having some intermittent power loss lately where the engine would just rev down and stumble along for a few seconds and then regain power.
I changed out the fuel filter and cleaned the fuel strainer.
Pumped up the filter till it was hard to push the pump, filled the fuel strainer and then started it.
It ran for a minute, then began to stumble. I was able to keep it running and started to drive it back to the shed when it stumbled again and then quit.
I have not been able to restart it since.
It will crank fine but no start.
I opened the fuel cap in case that was the issue but no go.
I am stumped [being relatively diesel ignorant].
This is a real problem with a winter storm on the horizon.
Any help is greatly appreciated

I had a similar problem (intermittent power loss/stumble) with my kubota bx2350. Like you I suspected fuel filters and changed them out. Unfortunately that didn’t resolve the issue. After a lot of head scratching and research I finally figured out it was the seat safety switch. Not my first suspect! I jumpered it as a test and then replaced it as the permanent cure. If you are stumped, you might check all of your safety switches starting with the seat switch. A volt meter works, as will a jumper wire or just tape the two leads together.

 

[Tx Jim]

After checking to be positive that my M7040 hyd shuttle lever & trans control lever are both in neutral position I've started engine while standing on the ground so I think seat switch isn't keeping his tractor engine from operating.

 

[Russ5160]

I was having some intermittent power loss lately where the engine would just rev down and stumble along for a few seconds and then regain power.
I changed out the fuel filter and cleaned the fuel strainer.
Pumped up the filter till it was hard to push the pump, filled the fuel strainer and then started it.
It ran for a minute, then began to stumble. I was able to keep it running and started to drive it back to the shed when it stumbled again and then quit.
I have not been able to restart it since.
It will crank fine but no start.
I opened the fuel cap in case that was the issue but no go.
I am stumped [being relatively diesel ignorant].
This is a real problem with a winter storm on the horizon.
Any help is greatly appreciated

You can pump up the filter, but you have to open the bleed and let the air out. Once the air is out, immediately close the bleed. It should run ok then.

 

[RancherGuy]

Lift pump is only 2 years old so likely it's ok. I will have to start tracing fuel flow path.

Good point. I had been thinking of the pump, but it seems strange to fail at such a young age. I can think if the following failure points. I have encountered all of these on a diesel.

a) Debris in fuel tank restricts or completely blocks flow.
b) Lift pump has failed or is intermittent.
c) Filter is plugged or incorrectly installed.
d) Unpurged air in lines or filter.
e) Suction break between filter and injection pump.
f) Injection pump issue (rare)

Here are the diagnostic steps that I would consider. Proceed down the list until a problem is revealed.

1. Make sure you are using the correct OEM filter. I once used a name brand, but it was actually an incorrect cross reference.
2. Do you hear the lift pump running when the ignition is turned to 'On'? (don't start it) Try a few times to ensure consistency.
3. Are you getting fuel to the injectors? Loosen the fuel line nut on one injector then as engine is cranking, fuel should escape at the nut.
4. Pull the fuel line that enters the fuel filter. Direct the loose line into an empty container (plastic milk carton works) to view fuel pumping when ignition is turned to 'On'. Flow should be steady and healthy.
5. Reconnect step 4 fuel line. Turn ignition to 'On' for a few minutes and ensure you see no wetness (fuel) anywhere on any line up to the injection pump. Use dry paper towel(s) to verify.
6. Analyze the fuel filter "seating" method and the line between the filter and injector to make sure air is not sucked into the injection pump. FYI, I have witnessed air entering at a hand-primer pump as well.

 

[fruitcakesa]

UPDATE:
Since it is a balmy 20*F day, I headed out to the tractor to work.
First off, I disconnected the line from the FF to the fuel tank and blew compressed air into the tank.
I heard it bubbling so guessed it was cleared if it had been blocked.
Attempted to start after pumping the primer many times. Still no start.
Then I pulled the line from the FF to the IP at the FF and cranked it and fuel flowed freely from the open port... OK we got fuel at the filter.
I then pump the primer 60 more times and tried a crank and it fired a few times...yesss!
More priming, cranking, popping. After about 4 rounds of this it fired and continued to run...yay
So, perhaps it was something in the tank blocking the outlet.
I guess at some point, if this is the case, it will eventually plug again since it would still be in the tank.
A little compressed air now and then I can manage. Dropping the tank to clean it is not a winter job for me.
I went out and box bladed the drive uphill at full throttle and it did not miss a beat.
Thanks to all for the great advice.

 

[dodge man]

I’d give it some time, still might have air in the system.

 

[piper184]

beware of "diesel bugs". Sounds like you might be infected. Cleaning screens and replacing filters is only a stop gap measure until you get the entire system purged, cleaned and sanitized of water.
At the very least, get a bottle of biocide and start treatment right away.

 

[CobyRupert]

When the injection pump is pumping small amounts of fuel and the injector lines have a lot of air in them the air will compress and not pop the injectors open to escape the system.

Ok..now that OP has tractor running and I won’t hijack thread…

Mechanical system: I understand air will compress, but if the pump is pumping fuel behind it, so what? Won’t the air eventually compress to the fuel pressure the pump is supplying and push air through the injector?
Or would this just take too much time cranking given the relative volume of the fuel lines to the amount of fuel injected?
Or does the fuel line “decompress” back into the pump between injection cycles, thus pressure never “builds” to pop injector.

I know lines from pump to injectors have to be bled of air, I just don’t know why.

 

[airbiscuit]

Biocide is cheap insurance.

 

[LouNY]

Ok..now that OP has tractor running and I won’t hijack thread…

Mechanical system: I understand air will compress, but if the pump is pumping fuel behind it, so what? Won’t the air eventually compress to the fuel pressure the pump is supplying and push air through the injector?
Or would this just take too much time cranking given the relative volume of the fuel lines to the amount of fuel injected?
Or does the fuel line “decompress” back into the pump between injection cycles, thus pressure never “builds” to pop injector.

I know lines from pump to injectors have to be bled of air, I just don’t know why.

From what I have seen it is a combination of things often. The air is compressing and pushing back as the pump lobes rotate.
If you can crank long enough it will usually purge out but not always.
I had an Oliver I worked on for a friend and we got it firing on 4 cylinders but had it running for several minutes with misses,
untill we cracked the lines at the injectors when we got to the misfiring ones as soon as we got fuel and tightned the lines back down the miss disappeared. This was an older Roosa-Master pump on a 6 cylinder Oliver.
When we have had a diesel that wouldn't start after a fuel issue if they will tow start it is the easiest and fastest way to get one going. Of course on many of the newer ones that will not work, the power shift transmissions and power shuttles won't pass power through the drivetrain.