Tractor stalls only when sudden load is applied?

[Josh in Pa]

I have an oliver 1550 gas that stalls if a load is applied suddenly, such as popping the clutch, or if you open the throttle quickly. If the load is applied slowly, it will put out full power and run well. What would cause this?
Josh
 

[ss55]

This is just a shot in the dark - a bad accelerator pump in an MS carburator? Dad's 4020 gas could stumble like that, it had an aluminum MS carburator that I think had an accelerator pump.
 

[Erik Ks farmer]

I am not familiar with this tractor, but have encountered something similar. In my case the tractor was starved for fuel due to a weak fuel lift pump.
 

[Bob Bancroft]

This is why most "automotive" carb's have an "accelerator pump".
Most likely when your governor pops the throttle plate wide open, particularly on an engine that is anything other than fully warmed up, the carb. just can't supply the gas needed for smooth acceleration.
If you can't overcome it by adjusting the carb. rich, perhaps a carb. cleaning would help.
 

[JD Seller]

It could be several things. The most common one is that the carburetor is set too lean. All you would need to do is open the load valve/high side a little. A more unusual one would be a bad coil. I had a Oliver 1650 that was doing the dieing under sudden load and it was the coil on it.
 

[barnE]

Governor
 

[flying belgian]

Yep. It is just the nature of the beast. My 560 gas was like that and my 706 gas was like that. You can adjust the carb as others have suggested until you are blue in the face and you will never get rid of it. Neighbors 1650 gas did the same thing. I have noticed it only happens to 6 cylinder tractors, not 4 cylinder. I don't know how to explain that.
 

[Bob Bancroft]

I'm going to guess that a six is enough bigger, and acclerates enough faster, that they all should have acclerator pumps on them.
I was going to say the same thing, but have little experience with six cyl. gas engines in tractors.
 

[Dalet]

[rrlund]

The 1550s don't have an accelerator pump. They're the old Marvel carb.

Does it idle OK? For some reason I always have to keep mine choked a little. The 1600 is the same way. Is yours better after it warms up some?

I had trouble with mine idling rough and it was sucking air where the intake manifold bolts to the exhaust. You might check for leaks there and for intake leaks where the manifold mounts up to the head.
 

[chucksoliver77]

Josh, Check the float level, if it is set to low it can create a lean condition. Chuck
 

[DeltaRed]

My first thought was too lean.As others have said,there could be other issues.Check/open the load screw first,thats the easiest and most common....
 

[fixerupper]

Is there an acceleratgor pump in that carb by chance? The 1850 gas and Deere 4020 gas had one and I think the 3020 gas did too. It was internal and vacuum sucked on a little piston with no seals. Nothing but trouble. Usually the accelerator pump made the tractor run rich when it had some wear on it. I finally plugged the vacuum hole for the accelerator pump on my 105 combine with a 4020 gas engine and after I did that I had to open the throttle very slowly. Ran fine wide open. Jim
 

[Brian G. NY]

I believe JD is on the right track; my WD Allis will stumble like that in the cold weather but if I open the main jet a 1/4 turn or so, it works fine.
In the summer I can lean it back up again.
 

[WGWKy2]

That is just one reason I do not have a gasser. I'm not smart enough to tune them up or don't take time to warm them up.