Engine Surging

[OntarioCanada]

I bought a 93 John Deere LX178 (15HP Kawasaki liquid cooled) a few weeks ago. It runs fine at fast idle, but when maybe half throttle and lower the engine surges (no load). I have already drained all of the old fuel (not sure how old it was), replaced the fuel line and filter, ordered a carb. kit which I should have within days. The plan is to obviously tear down the carb. and give it a good cleaning. When removing the carbeurator, I found a large washer in the carbeurator throat (at what I would call the primary butterfly, or the one furthest from the engine). I suppose someone placed it there to hopefully aleviate the surging.

Do you think this will solve the problem, or is there perhaps something else that I should be looking at?

Sorry for the long post. Any help would be greatly appreciated.
Thank you in advance
Paul

 

[RalphVa]

Surging or hunting is usually caused by the fuel mixture being too rich.

Ralph

 

[bontai_Joe]

I've run across engines that really need to run a little rich (and thereby surge) when under no load so that they will run correctly when under load. The idea being I guess that the machine will see a load 90% of the time so that's what it's tuned for.

 

[TimS]

I'm not familiar with this model, but it must have some type of governor on it. Usually there is some type of tension adjustment on the linkage between the governor itself and the throttle linkage. I have seen it take the form of a spring that can be placed in different holes to provide more or less tension. I might be worth looking at what you have and try some adjustment, see if it makes any difference.

Tim

 

[Mickey_Fx]

Guess my experience is a little different than a couple here. I associate surging with a lean condition.

If it is lean, could be just an adjustment or a partially blocked fuel passage that requires some cleaning to correct. From your comment on replacing OLD fuel, could be a partial blockage that has brought this on.

 

[RETIRED]

When my X585 (25hp kawasaki) was surging the problem turned out to be the fuel pump.

 

[OntarioCanada]

I have thought about the fuel pump, but figured that it would be at higher fuel demands that it would experience problems.

As for the governor, while removing the carb (if memory serves me right) there was only one hole for the spring to be installed at either end. I'll have to take a closer look at it. My carb kit (gasket kit they call it) is in now so maybe today I'll go pick it up (20 minute drive).

I appreciate all of the replies, and will see what happens after the carb is finally all cleaned up and reinstalled.

Not sure when this will all be put back together cause my little 4 year old has some sort of virus they're telling me anyway. She's had a fever on and off for over 7 days. She's also a type-1 diabetic which makes this much worse. There have been a lot of sleepless nights in the last week........

I'll keep you posted, as it's always good to let people know the cause of any problems.......assuming of course this gets resolved.