Mowing X300 idle problems

[bmg88201]

I have an X 300 that now won't idle correctly, it just revs up and down up an down and won't idle at a constant rpm, on full throttle it still does not keep a constant rpm but it is not real noticeable but at idle it is real bad. If I try to drive it at idle it just lunges then creeps then lunges then creeps, probably due to the poor idle. New plugs no help, new fuel filter no help. Took the air filter housing off and just inspected the carb but did not see anything amiss. Any advice or suggestions would be greatly appreciated.

Thanks,

 

[tomplum]

It tends to be an obstruction in an idle circuit / bleed in the carburetor. So remove the carb and clean inspecting the float valve for wear whilst you are in there.

 

[bmg88201]

Sprayed the carb inside the best I could without taking it off, the carb linkage looks like a bear to get off, I guess you have to take off the whole linkage/cable bracket below the carb. I remember an old STX 38 I had that the part with wires running to it on the bottom of the carb bowl went bad, maybe that is it. Oh well, I'll keep jacking with it or finally take it to a small engine guy but I like to fix stuff myself.

Thanks for your input,

 

[tomplum]

Nope. Just have remove nuts, fuel line, slide the carb back, unhook the spring at the throttle lever and twist out the linkage. You may have to extract a mounting stud using the two nuts locked to twist it out. That's worse case.

 

[bmg88201]

Thanks, I'll give that a try. I really don't want to try to take out the two mounting bolts, since they screw into aluminum. But if I do I will put some graphite/copper anti-seize on them going back in.

Once again, thanks for the input.

 

[tomplum]

One thing you could try before removing the carb. The ones that get dirt in bore this can help with. This really depends on the specific carb on your X 300, but look inside the bore and you may see 1 or 2 brass orifices in the bore. A couple second blast of carb spray through them may help your situation. You can do this running if the carb is tight. Only the early ones have a a removable idle screw at the rear of the carb. Should it need to come apart and you see wear on the float valve and a Deere dealer is not near by, I can give you a compatible Briggs part number which is real common.

 

[bmg88201]

I will check out what you suggest, it is certainly worth a try. My X300 is a 2010 model, it's got 500 hours on it, don't know if that means anything, it's been a running jenny so far. But one thing for sure, I'd rather rebuild a transmission than work on a carb, ugh.

Appreciate your time and advice.

 

[Gem99ultra]

Very often a gasket will dry out, or a connection will vibrate a little loose, and cause this problem.

Sounds like a vacuum leak to me. Common problem. You can easily check for that by spraying carb cleaner around every joint/connection from the carb to the intake. If the idle smooths out, you've found the problem. Even an old vacuum line can leak just a little and cause the constant surging.

 

[bmg88201]

Well, I was able to get the carb off without taking out the mounting studs, but I didn't like bending the linkage forward so far, I sprayed the heck out of it with carb cleaner, every nook and cranny, gaskets were intact, fuel line was in good shape, no evidence of fuel a fuel leak. I did not take off the bowl. I snugged it all back up and it idles just fine now. I drove it around a few laps at low and high rpm's and killed it and started it up a couple more times and it seemed to idle and run fine now. Must have been some trash, I suppose. I guess I'll know for sure next week when I mow for four hours solid.

Great advice from both of you, thanks.

 

[mini14]

When the older Kawasaki FH engines I had on my mowers would do that I knew it was time to replace the intake manifold gaskets.