Small engine question

Maybe the switch under the seat (assuming there is one)? It would make sense to me that they wouldn't want the PTO engaged if you're not seated, and they wouldn't want the mower moving without an operator in the seat.

The seat switch has been bypassed. If it weren't working, I wouldn't be able to start it. The PTO should be stalled by the reverse switch. The brake not being depressed when starting prevents the engine from turning over. After that, there should nothing involved. Releasing it after starting not do anything.

It dawned on me, I shouldn't even be able to start the pto with the brake on.

Not to hijack thread, found something new last night. My tractor cut out 1.5 hrs after carb cleaning, there was material in the bowl that looked like diaphragm. Replaced the fuel filter, remaining fuel hose, cleaned orifices, lines and solenoid again. Opened the fuel pump, diaphragm was like new but outlet check valve was loose, it fell out on the bench, paper gasket in the seat was coming apart.

Here's the kicker though... read the leads on the solenoid w/ DVOM. 12V+ key on, 7.2 to 9.5V when cranking, no start. Seemed like it would crank all day tho. Charged battery to 14V plus. Solenoid voltage was at least 12V now during cranking and it started right away.

Gonna see what voltage the battery holds today. Maybe try to delete the solenoid w/ old carb parts if I can. JB weld the pump check valves in their seats. Gotta love old tractors.

Those carb solenoids aren't cheap and all they are designed to do is to kelp fight backfires. Just like all these safety switches are designed to keep us from killing ourselves but, in reality, keep dealers afloat.

In reply to markwemple:

That Walbro solenoid runs around $100 if you can find one. My solenoid runs kinda hot for my comfort but don't know the real nature of that beast, it don't like low voltage for sure. New battery may help but I'd rather just delete the solenoid, it is almost 20 y/o. Current battery cranks like a champ. I hate throwin' money at E36 M3.

I've successfully eliminated one of those solenoids with the regular stubby bolt you find on the older fixed jet carbs.

Got the wiring figured for now. She's been buggered with too many times. Now back to the carb. I can't use more than 1/2 throttle or she'll die. Which, of course, isn't enough to mow with. I know I suck at carbs but maybe it's time for a pro? Meanwhile my grass is getting really long.

Something is clogged in the high speed circuit. With the air filter off try getting it as revved up as you can and then briefly slam your hand over the intake to choke it hard (not long enough to kill it) repeat a few times, sometimes those hard vacuum pulses will pull the junk through.

If I keep it choked it will stay running throttle up, but it dies off then runs, then dies, then runs, etc. Maybe too rich?

Sounds like a lean surge to me, main jet bore varnished up, clogged emulsion tube, insufficient fuel flow, etc.

I had a carb that had no power at full throttle. I finally found an air vent that lead from behind the throttle plate to the high speed circuit was plugged. It looked like a metal plug was in it but it turned out to be a small piece of rock. It took a bit to clean out but once I did it ran great at high speed.

Damn thing is still doing it. Pulled it completely apart and cleaned (soaked in carb clean for 2 days). Replaced O-rings. Sprayed everything with spray carb clean before putting together. Still hunts on high and only with choke on. I guess new carb time?

Dunno about your Keihin but the Walbro on my 15 hp Kohler single has a carb/ cable adjustment. Dowel or tapered punch aligns it. Only had to adjust it once about 5 yrs ago but I check it every season.

I had similar issue and had to run w/ choke partially closed on high. Had small rubber bits in bowl, replaced remaining old fuel hose and w/ new fuel filter. It ran for a while till I found gasket material in the bowl. Fuel pump checks loosened up and gaskets were coming apart. JB Welded the checks in.

Battery voltage was 12.7 after running. 12.45 a day later and 12.25 the next day. It would crank like a champ all day tho. Thought the fuel solenoid was goin' out then reading 7-9V while cranking but replaced the battery and all is good now. 3 hrs run time since n purrin' like a kitten.

So, at least three issues that needed corrected. What's the chance of that/ old tractors.

Pulled yhe carb apart and there was a little something in with the gas in the bowl. Time to drain the entire system again. By something, I mean like water or something. This is driving me crazy.