Loss of power

[brooster1973]

I own a L3940 HSTG with less than 700 hrs. I had to replace the left hand side brake housing and so I replaced the hydro filters and refilled with super UDT fluid, changed fuel filter and oil and oil filter, and also both air filters. I had an issue after with pulling small hills in mid range high, engine would start to bog down, could shift to low range and it would pull fine. I had no issues with power before doing this service. I had no problems running front end loader or backhoe, thought maybe air in fuel line so I have bled it per repair manual instructions. Yesterday got in it after it sat for about 3 weeks, started right up and ran fine for about ten minutes but then started losing power on flat ground, switched to low range and would barely move, parked it and when I tried to rev it up it would start to rev and then drop to a slow idle. I again bled fuel line a couple more times but no change. Anyone got any ideas?

 

[JWR]

It is a fuel issue. Many similar symptoms on many threads. I would bleed each individual injector line (loosen it and let it squirt a while) and go from there. Probably still air somewhere in the lines . Could have gotten tiny debris into the fuel path changing the filter. Who knows. Just process of elimination. But I think it has to be fuel. I assume the tank is vented..

 

[brooster1973]

It is a fuel issue. Many similar symptoms on many threads. I would bleed each individual injector line (loosen it and let it squirt a while) and go from there. Probably still air somewhere in the lines . Could have gotten tiny debris into the fuel path changing the filter. Who knows. Just process of elimination. But I think it has to be fuel. I assume the tank is vented..

 

[brooster1973]

I will try next day or so to crack the injectors but you can’t even see them on top of the motor!

 

[Jerry/MT]

I own a L3940 HSTG with less than 700 hrs. I had to replace the left hand side brake housing and so I replaced the hydro filters and refilled with super UDT fluid, changed fuel filter and oil and oil filter, and also both air filters. I had an issue after with pulling small hills in mid range high, engine would start to bog down, could shift to low range and it would pull fine. I had no issues with power before doing this service. I had no problems running front end loader or backhoe, thought maybe air in fuel line so I have bled it per repair manual instructions. Yesterday got in it after it sat for about 3 weeks, started right up and ran fine for about ten minutes but then started losing power on flat ground, switched to low range and would barely move, parked it and when I tried to rev it up it would start to rev and then drop to a slow idle. I again bled fuel line a couple more times but no change. Anyone got any ideas?

I would start at the tank and verify that the fuel gushes out CONTINUOUSLY. If it is intermittent, or dribbles, you found your problem. How about the lift pump? remove the outlet hose and crank the engine. Do you get a big gush of fuel continuously? Some lift pumps have a screen in them that can clog. Check for that. Trash can accumulate in the filter head, lines can get damaged or pinched. Check those out

 

[bullockcm]

Seems strange after the maintenance but I would follow Jerry's advice. Don't be like me... Saga is posted on here many years ago. Short version was my lift pump failed quite early in the life of my L4240. Was misdiagnosed as "air in the lines", then the dealer just started cracking fuel lines to bleed the system and managed to take the high pressure fuel pump out of calibration. After much back and forth a second dealer repaired the tractor under warrenty, all for a $18 lift pump.

One other thought, have you tried to rev the tractor with auto throttle both engaged and disengaged?