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'98 Mule 2510 nightmare

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So, this unit comes in for hard to start, wont idle, and have to throttle and choke it to keep it running. Of course higher RPMs make shifting into gear awful.  It has the FD620D engine, 808 hrs, ranch vehicle but not abused. I rebuilt the carb, (the right way with dip soak and all the brass), replaced plugs, fuel filter, checked fuel flow from pump, dumped tank and put in fresh gas. It runs some better, but still wont idle or midrange without 1/2-3/4 choke. Very lean, but flowing good amount of fuel through main jets. I've checked for vacuum leak(s), and none found.

I have checked coils for proper resistance and found slightly above spec readings across primary terminals but secondary ok.  My query is, can the igniter box go out of "calibration" and change the timing on the coils and cause an advanced condition? The engine does "kick" once in a while when starting it. This could also cause the engine to seem to run lean.

Any suggestions are  greatly appreciated. I prefer that it be the "box" to change rather than the space-locked rear coil! What the hell were they thinking?!

Thanks in advance .











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Its the way some engines react when timing is advanced too far. And if valves were out of time the engine wouldnt  run.  It runs pretty good with the "rich" condition it has with choke partially closed.

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Any chance of swapping the carb with a known good running one? I know that you feel confident that's not the problem any longer. But it sure sounds like it's a carb issue. Since you've said it runs pretty good with the choke. Maybe some crud got missed, or a float, or jet problem causing this? From the description it sounds like a fuel issue. Can't help you on your specific question about the igniter box though.

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Thanks for the thoughts. The funny thing is, even running for a short time with the choke partially closed, the plugs really soot up. That tells me its  getting more fuel than it can burn properly.  And these $275-300  carbs aren't a common inventory part.

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Your symptoms sure sounds like the idle circuit in the carb is plugged or otherwise restricted.  The reason it runs a little better with the choke and/or partial throttle it because that's bypassing the idle circuit and you're running on the high speed circuit.  I would also check the float level.  That can cause excessive fuel (rich condition) that can cause sooting of the plugs and flooding of the engine.

Both conditions can cause hard starting and rough running engines.  Lesson I learned in high school auto shop long, long time ago before fuel injection was discovered.

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