Engine speed issues

[Tractor novice]

I'm a first time tractor owner in need of some help. I'd get right to the problem, but I think some history is pertinent. I recently purchased an L1500. Started and ran fine when I looked at it and when I picked it up. Once home it was very hard to get started, lots of cranking and glow plugs. I also noticed when I used the loader or tried to run mower it seemed to lack power. Then finally couldn't get it to start at all. Did usual service, oil and all filters changed, drained old fuel put new in and also new glow plugs. Got it to start again and seemed good just sitting running. Next try wouldn't start. Checked compression and was low. Put new pistons and rings in on original rods, new gaskets and o-ring on oil sump tube. Relashed the valves and compression test was much higher. Tractor started right up, ran it at idle for few minutes, then about half throttle, back to idle and shut off to check for leaks and recheck fluid levels. Restarted and it ran at idle for a few seconds, then started speeding up without moving throttle to the point I shut it off. Did this 3 times in a row. I started checking fuel issue first and found that the speed control assembly was moving, but the rack arm wasn't. Took assembly off to look for broken spring or something, but everything looked fine and I could move fork levers and rack arm back and forth very smoothly with my fingers. I thought maybe I had gotten a piece of debris around the rack arm making it stick so I reassembled and everything moved together fine. I tried again, this time it started, but never sped up to idle speed and died. I increased the throttle a little and tried again, this time it started right up again but still just barely running. It did stay running this time though, so I gave it some more throttle to try and get the engine up to good idling speed, but the engine never sped up it just started billowing heavy black smoke so I shut it down again. It seemed as though when I increased throttle, it got more fuel and was burning very, very rich because of the smoke created, but engine still didn't speed up. I admit I'm not a mechanic, so does this sound like something wrong from the piston change, or maybe a governor issue. I'm not sure what to look at or try next. Any help would be appreciated.

 

[K.P.]

Are you using fresh fuel? Was tractor sitting for a long time with old fuel in the tank and fuel delivery system? I had similar problem with a tractor that had 6 year old diesel. Bad sludge in bottom of tank and bacteria growth on sides of tank. There are simpler ways to resolve an issue like that but I replaced tank and everything between the tank and injectors. All the power in the world now...for a little 16hp.

 

[Tractor novice]

Yes, I drained fuel tank, put in new fuel and drained that out to flush out before refilling. I also took fuel injection pump apart and checked it over when I did the initial servicing. Internally it looked like new.

 

[North Idaho Wolfman]

Did you pull the injection pump out?

Did you remove the gears in the gearcase at anypoint?

Did you check and recheck the valve lash?

Did you remove the governor?

 

[Mark15]

Might want to check the air intake side of things. Heavy black smoke can mean fuel without enough air to burn it.

A heavily restricted air intake could also cause it to barely run and / or stall out.

 

[Tractor novice]

Yes, I pulled injection pump out and went through it. Everything good and worked fine after reinstalling it.

I have not removed the gearcase or messed with any of the gears.

I did check the valve lash after changing pistons and reassmbly. Set to .009".

I am not exactly sure what the governor is. I pulled the speed control assembly off and removed the "governor" spring from the speed control arm. When that was out I could see what looked like a throw out bearing around the fuel camshaft next to it's gear. There was also a small roller sitting on top of the gear with a shaft sticking out that the fork lever would push in if the governor spring pulled it back far enough (this would be in the high throttle direction). I am guessing pushing that shaft in would lock the roller, causing a drag on the gear, slowing the camshaft and fuel pump to slow the engine from overrevving. But only a guess and other than pushing that shaft in a couple of times, I did not mess with anything else.

I will recheck the air intake. Even though I changed the filter and cleaned it's canister, that has been a while back and dirt and "critters" can be pretty invasive.

 

[rentthis]

When you replaced the injector pump, are you certain that you replaced all it's shims?

 

[RCW]

Gosh - don't know the workings on your model or any experience tinkering with them, but the description leads me to governor.

A governor helps regulate/modulate engine RPM, often by changes in centrifugal forces with RPM changes. The governor is connected to the fuel system to accomplish that, and many operate by rotating weights/springs.

While it's a new replacement, my Dad believes he has a still has a governor issue with his Minneapolis Moline. Since he's operated since the 1950's, I have to take his word. It will shortly be mine, and that's the first on the repair/restore list.

 

[RCW]

I pulled the speed control assembly off and removed the "governor" spring from the speed control arm.

Sorry - missed that before. Did all go back together fine?

Again, no first-hand experience, but I know governors/linkages/springs can be finicky. (possible issue with my Dad's 'Moline)

Would be my first suspect, but I'm guessing some too.

Good luck!!

 

[North Idaho Wolfman]

Do you have the WSM or did you do all of this by the seat of your pants?

I don't recommend anyone, especially a novice to get into the injection pump unless they have someone to help them.

If you pulled it apart, you most likely did not get it put back together properly and the rack and pump timing is off.

 

[Tractor novice]

I do have a WSM I got from Messicks that was helpful with torque and valve lash specs.. But I must say that mine is pretty much disassembly and trouble shooting info, and has no reference to injection pump or bleeding fuel lines or many of the things I've read on here to check the book for.

I did have a friend who is much more of a mechanic than me help with the fuel pump. I must admit it took a couple of times to figure out the flow pattern and get the gears and pump elements lined up just right. Thank goodness for the internet.

As far as shims, there were none on mine, it sits directly on top of the housing. It's a good thing too, because the rack arm still barely sits down in that deep notch of the fork lever and there is no way I'm aware of to raise the lever. The top of the arm is just slightly above the top of the lever. Since the lever pivots instead of sliding, you can actually push the lever far enough forward with your fingers that the arm isn't even in the notch anymore but it does catch it coming back.

I believe I am on the track of the problem. Because of the support beam for the loader running right in front of the access port of the injection pump my angle of vision is less than desirable. While I thought the fork levers were moving the rack correctly I was mistaken. Finding a better angle, I could see it was only moving a little bit, and that was toward the full throttle end. I also noticed a large amount of slop between the movement of the 2 levers. I determined that the governor spring must have gotten stretched to long. I bent the hook on one end tighter and the levers not only moved together, but I could see much more range of movement in the rack arm. I believe when it sped itself up, it was due to this slop and vibration bouncing the lever and rack arm toward higher throttle. Then, even though I moved the throttle to idle position on the next instances, the rack arm didn't move down so I was trying to start it at very high throttle, essentially choking it.

I did restart today with much better results. Engine started much more normal and did not speed itself up, but it did seem to be running a little faster than it should when at low throttle, so now spring may be just a little to short. I am hoping to be able to fiddle with it some more tomorrow to try and dial it in better. Just shows how even a little difference in the length of a small spring can really affect things.

I will let you know how it turns out.

 

[North Idaho Wolfman]

The springs are not the adjustment point to idle or top end speed, they are just transfer devices for the Governor movements.

Buy new springs!

 

[Tractor novice]

Well, I was pretty sure of that. I didn't mean to suggest that changing the length of the spring was the fix. I am trying to diagnose a problem. From what I see of how these levers should work, and by the positive changes I've seen by changing the length, it tells me that the length and strength of the spring matters in the functioning of the governor. If I can get the engine to run from idle to full speed, controlled by the the throttle again just by messing with the spring, I can feel pretty confident that is where the problem is and not in some other part of the governor, or engine for that matter. Then, of course, the fix will be to buy new springs.