L-3750 Problem...

[Bear-L3750]

Good evening folks!! New to the Forum. OK I recently purchased a 1989(?) L-3750. Started using it and it ran great initially then stated losing power. The engine started revving up and down then finally chokes out. Changed the fuel filter and put new fuel in it. Here is what's happening...It fires right up and after about 2-minutes idles down and purrs perfectly. Take off to go to the food plots and about a 1/4 mile (hitting a small hill) it starts spitting/sputtering, revs up/down chugs a little farther, then just dies. Trying to re-start it takes about 20-minutes and runs for a few 100 feet and dies again. Let the thing set over night and it "fires right up" idles great, then it happens all over again. Tractor has 1300-hrs. It has not been to the service since I bought it. Oil/filter was recently changed, all fluids are full. I was putting "on road" diesel in it with "Bio-Diesel" additive. The 1st time it did this I played around with it and finally it "all of a sudden" ran great. I tore up a lot of dirt for 5-6 hrs, got done for the day and parked it. Went back the next morning fires right up idles great and the same crap again. It hasn't run right again. What confuses me is why did it run GREAT for that for 5-6 hrs, after sitting over night idles perfectly, then starts this again???? Sorry for the lengthy post, just want to get all the info out there. Thanks for any advice in advance!!!

 

[freewheel3]

Good evening folks!! New to the Forum. OK I recently purchased a 1989(?) L-3750. Started using it and it ran great initially then stated losing power. The engine started revving up and down then finally chokes out. Changed the fuel filter and put new fuel in it. Here is what's happening...It fires right up and after about 2-minutes idles down and purrs perfectly. Take off to go to the food plots and about a 1/4 mile (hitting a small hill) it starts spitting/sputtering, revs up/down chugs a little farther, then just dies. Trying to re-start it takes about 20-minutes and runs for a few 100 feet and dies again. Let the thing set over night and it "fires right up" idles great, then it happens all over again. Tractor has 1300-hrs. It has not been to the service since I bought it. Oil/filter was recently changed, all fluids are full. I was putting "on road" diesel in it with "Bio-Diesel" additive. The 1st time it did this I played around with it and finally it "all of a sudden" ran great. I tore up a lot of dirt for 5-6 hrs, got done for the day and parked it. Went back the next morning fires right up idles great and the same crap again. It hasn't run right again. What confuses me is why did it run GREAT for that for 5-6 hrs, after sitting over night idles perfectly, then starts this again???? Sorry for the lengthy post, just want to get all the info out there. Thanks for any advice in advance!!!

Classic symptoms of a blockage in the fuel system or air being allowed in to the fuel system (probably upstream of the lift pump). So check all connections for tightness. Make sure the petcock on the fuel tank is fully open. Check for good fuel delivery out of the lift pump into the injection pump (should fill a pop can in about 15 seconds). If not good delivery then consider changing the filter again and possibly checking for a blocked suction screen on fuel line inside of tank. Another possibility is collapsed fuel line somewhere in the suction side of the system or tank is airlocking due to not venting properly (rare).

 

[Bear-L3750]

Classic symptoms of a blockage in the fuel system or air being allowed in to the fuel system (probably upstream of the lift pump). So check all connections for tightness. Make sure the petcock on the fuel tank is fully open. Check for good fuel delivery out of the lift pump into the injection pump (should fill a pop can in about 15 seconds). If not good delivery then consider changing the filter again and possibly checking for a blocked suction screen on fuel line inside of tank. Another possibility is collapsed fuel line somewhere in the suction side of the system or tank is airlocking due to not venting properly (rare).

Freewheel, Thanks for the reply. Not to sound ignorant (new to tractors) I understand everything and will check them, but where is the lift pump, in the tank?.

 

[GWD]

It might be that gasoline was accidentally put in the tank during refilling. It causes the symptoms you cite.

It could be something else but the fuel is just one more thing to check. The odor of gasoline is different than that of diesel.

 

[Bulldog]

Look where the fuel line goes in (hooks to) the injector pump. If it has a small round knob make sure it's closed (clockwise) fully. Works like a champ when you change filters but if it's left open it will make the engine run bad.

 

[freewheel3]

I'm not sure where the lift pump is located on your particular unit but if you trace the fuel line from the tank you should find it downstream of the fuel filter. Also, I think there is 2 fuel filters on your machine, did u change them both?

 

[Bear-L3750]

Bulldog, I've opened and closed that knob, and beleive it or not, it starts better with it open. But I do close it when it starts.....There is a round "disc" with about 8 little screws, just below that knob, where the fuel lines go into. Is that the injector pump? Thanks...

 

[Bear-L3750]

Freewheel3, I've only found the one filter in the glass bowl, and I've followed the fuel lines all the way up. I will look again.....Thanks

 

[Bulldog]

Bulldog, I've opened and closed that knob, and beleive it or not, it starts better with it open.

When you open that knob and crank the engine over it creates a vaccum on the fuel line comming from the filter to the injector pump. With the system already primed you shouldn't have to use the knob to start the engine. If it does start easier with it open I would go back over all the fuel system all the way back to and including the tank.

Are any of the fuel lines wet looking?

Have you checked the vent for the tank? It will either have vent tubes or the fuel cap will have a vent in it.