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Discussion Starter · #1 ·
860 hours on my X540

10 minutes into cutting the grass, it starts to surge...
If i let it sit for a few minutes...then it runs great.... for another 10 minutes then surges again and i need to ride the choke to get it back into the garage... then let it sit and it will be fine again for another 10 minutes...over and over again....
  1. replaced fuel filter
  2. replaced fuel pump
  3. cleaned the carbs (did NOT replace jets... just sprayed it down and inspected inside)
Should i replace the jets? replace the carb?

ALSO: what are the external screws #28 in the schematic of the carb??

thx!!
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I'm not sure but #28 looks like the idle air or idle mix screw, the kind with the EPA limiter plastic cap on it. Also, maybe you have an issue with the gas cap vent or there is a restriction in the fuel line ie. Filter or collapsed line


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Leave your gas cap loose and try it again.
 

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Jerk of all trades
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Run some seafoam thru the fuel system
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It can't hurt ..
 

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It could be some debris floating around in the carburetor, so Sea Foam might help, but I would not try different jets, as they are calibrated to your engine's needs, which haven't changed. The only caveat to that would be if you have a jet that is plugged and can't be cleaned, then you could replace them with jets of the same size, although, it is unlikely they would not be cleanable.

The other thing to look for is weak spark after the engine warms up, which could be overcome by the richer mixture the choke provides. Get a spark tester and test the color of the spark when it starts acting up. White or blue is good, yellow or orange is weak.
 

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Agree that it sounds like a carb issue. Fuel must be getting to the carb if application of some choke gets him back to the garage. That extra fuel provided by choking has to be in the bowl for that to work. Just to eliminate it, run the machine until it acts up. Then remove the plug wires, pull the fuel line off, stick the end into a deep jar, and crank the engine. Observe to see if good quantity of fuel is pumped into the jar. If so, it isn't the lines (as you have already replaced the fuel pump). Also inspect the fuel for anything laying in the bottom like water or debris.

Like MarkLI says, I'd concentrate on getting all the jets and passages in the carb thoroughly cleaned. Get some cleaning tools as he suggests, will make it easier to clean and more likely to get the thing clean. Use a parts cleaner dip or preferably a vibrating and heated dip tank if you have one, or can use someone else's. Reassembly should be careful including being sure all gaskets, carb and carb to block, seal out air leaks.

My bet is there is still something that is floating around in one of the carb passages or jets that needs to be cleaned and flushed out.

You didn't mention if this just came on suddenly or has been there and getting worse. Knowing might give MTF members a further clue.
 

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I fixed a neighbors pressure washer that had similar surging. There was debris in the tank that would get drawn to the outlet while running, let it sit for a few and it would run normally before surging again. Once the tank was cleaned the problem went away.
 

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I had beetle bugs crawl into a small hole in a broken gas cap. They died and fell to the bottom of the tank where they got lightly sucked into fitting to the fuel line. As I ran the tractor, I had to keep richening the carb because the bugs got sucked tighter into the line. After the tractor sat for the night, the dead bugs would loosen up. So when I restarted it, the carb was way rich but would lean out during use again.
 

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Discussion Starter · #13 ·
hi all
ok carb apart
bought all new jets
soaking in parts cleaner now

question: see the spring #18. i’m positive that was UNDER the jet #26.(ie jet screws into the spring) but i’m really doubting myself for reassembly. plus diagram shows it OVER (sitting on top of) jet # 26. lol i can’t remember!!! ANY SUGGESTIONS?? under or over ???

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