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So I got this mower and it need some work. Got it running replaced steering, rebuilt carb, new filters among other things. Mowed great for a while then it started hesitating and losing power. Checked fuel lines and such and replaced fuel filter, cleaned tank seemed to work. Pulled carb apart again to check needle valve and it's fine. When I put back on it started up but was running so rich it barely ran and when I turned key off it started running perfectly, better than ever before. I messed with it a bit but finally started it, turned key off drove it around and tried PTO but no activation, no electric to it. When key went on motor ran like crap again but PTO engaged and almost killed engine. I am stumped with this, have no idea what the issue is but it appears electrical to me. Any thoughts?? Help is appreciated.

Is kill wire attached to ignition module(coil)? If fuel solenoid has not been tampered with then it sounds like it's running too rich and when power is cut to fuel solenoid, plunger extends leaning out the fuel mixture.

o modifications at all just cleaning and maintenance. I noted there are not adjustment screws for the mixture on the carb, what would cause the rich condition?

Mikel1 said:

Is kill wire attached to ignition module(coil)? If fuel solenoid has not been tampered with then it sounds like it's running too rich and when power is cut to fuel solenoid, plunger extends leaning out the fuel mixture.

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Float valve(needle) problem also check float , you said filters so I take it you have replaced the air filter.

Over rich, check the post above, problem with turning it off and run, check out the key switch.

Twin cylinder engines that have two separate ignition coils and shut down with a single key switch have a "Y" electrical harness which have a diode installed in each leg of the Y. These diodes allow the engine to be shut down by a single wire connected to the key switch and prevent back feed from the coil primarys to each other preventing the engine from being shut down.
Different symptoms happen depending if either diode is electrically shorted or open.
A defective key switch is another possibility.

So pulled carb and put a rebuild kit in not a lot of stuff but did it. backfire solenoind OK it is operating as i checked it out off of mower. Visually inspected wiring to see if chewed through by a critter and it appeared OK. Put carb back on and bam same issue, too much fuel pouring in when key is on and rns wiht key off, this time it shut off after a second or so. There are no adjustment screws for the fuel mixture or a replaceable jet so I don't understand why it would start this. It did run OK when I got it the hesitatioin and power loss got continually worse hence searching for the issue now this! Any ideas? wherer ar these diodes? is it a rectifier? i found a couple of electrical items in the circuit I can't identify, I'll have to look tonight for a schematic. Thanks in advance.

Choke working properly and have the spark plugs been replaced?

nazbom said:

So pulled carb and put a rebuild kit in not a lot of stuff but did it. backfire solenoind OK it is operating as i checked it out off of mower. Visually inspected wiring to see if chewed through by a critter and it appeared OK. Put carb back on and bam same issue, too much fuel pouring in when key is on and rns wiht key off, this time it shut off after a second or so. There are no adjustment screws for the fuel mixture or a replaceable jet so I don't understand why it would start this. It did run OK when I got it the hesitatioin and power loss got continually worse hence searching for the issue now this! Any ideas? wherer ar these diodes? is it a rectifier? i found a couple of electrical items in the circuit I can't identify, I'll have to look tonight for a schematic. Thanks in advance.

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Get the engine model and type numbers and look for the parts manuals for your engine make. The diodes are installed in the Y harness which is an engine part.

Carb completely re-built, new jet solved the running rich issue and the unit shuts off properly, cleaned all connections on ignition switch and it shuts off properly. The solenoid wasn't seating properly and fuel was leaking past main jet to engine. Now it runs better but not right. Still has a low power issue. I adjusted valves to 5 thous per the JD mechanic at my local JD dealer (who was gracious enough to talk with me about the issues). SO new fuel pump and filter, rebuilt and cleaned carb, plugs changed and it still seems to be searching for it's correct high idle and when gets to cutting grass begins to bog and lose RPM's it doesn't stall but is struggling like I have a 3.5 HP motor on the tractor. I can't see it being a fuel issue after all this???????

Are both cylinders working?

Yes both cyl are working. Used a spark tester tonight and good to go. Filled tank completely (and yes vent hole is clear) and ran mower, ran great mowed a couple acres. Parked mower and messed with steering some. Started mower after about two hours and acting up again. Low power acts like running out of fuel, when PTO is engaged it struggles to mow grass. I'm perplexed, one thing I noted is that early the fuel filter was at normal level about half with the line to fuel pump picking the fuel up, when it was acting up the fuel filter was totally full of fuel and normally they have air space in there. I can't figure out what is going on here but I think it has to be related to the fuel somehow.