So, I was using one of my EK-10's the other day after fixing it up (more on that later...) and I noticed that I was having some problems with the engine running. It seems odd though since it initially started running fine when I first started it up to mow the lawn with. It did seem odd though that it wouldn't start unless I choked it all the way, despite it being 90 degrees outside. I figured it shouldn't need any choke at those temperatures and quite often my 850 would start with no choke needed when it was warm out. But in any event, it started and I got it going. It also seemed that I couldn't give it full throttle until it warmed up a bit or else it would start to cut out. But once it warmed up a bit, I started mowing and everything was fine.
I finished up the front and part of the back when it ran out of gas, so I filled it up and went to start it again and it was giving me trouble starting back up again after having run it for over an hour with no problems. I had to choke it again to get it to fire and it was puffing out black smoke. Once I got it running and I shut the choke off, it smoothed out a bit and started idling fine, but once I started to try to rev it up to operating speed, it was breaking up and sounded like it was going to die on me. So, I brought the throttle back down and it went back to idling fine again. I let it idle for a bit and turned the main jet adjustment screw on the carburetor out about 1/2 turn. I tried giving it some more throttle again slowly and eventually it seemed to get up to operating speed once again, so I closed the engine cover and hopped on it to continue mowing, but when I engaged the PTO, the engine bogged right down and stalled. I'm like, WTF??? It was just running fine earlier! So, I start it again, mess around with the main jet adjustment some more, rev it up and try mowing again, and the engine keeps cutting out on me under load. I let it sit for a while to cool off some more and took the time to re-seat the main jet screw and then turn it out 1 and 1/2 turns to try to reset it, then started it up again. I did finally manage to get it going again and I could engage the PTO even, but with the deck running and even in only 1st gear, the engine kept surging like it was reving up and down by about 500 RPMs or so.
So, what gives with this engine? Was it just not happy with the heat? I was using good 93 octane gas, so bad fuel shouldn't be an issue. I did notice the PO put an in-line fuel filter in the fuel line before the carb, could it be plugged up and should I get rid of it and put a new fuel line on? Could this be a spark issue and not fuel at all? IDK if I need a new coil wire or not. The end boot where it goes onto the coil looks pretty dried out, hard and brittle. But it seems to spark enough at least to get it running and it always idles fine. I just can't seem to get it to run at operating speed (like 3,800-4,200 RPM or so) under load (both the deck and the transaxle running). I replaced the belts I was using before as well since they kept falling off the pulleys and binding up and causing problems, so I threw another new set of belts on it that I found in the boxes of parts and it seems to have resolved that problem at least. The only issue I have now is that the drive belts seem to slip a bit on occasion, especially going uphill. I can hear them squeal a bit when this happens.
Any help would be appreciated getting to the bottom of this issue so I can just use this EK-10 this summer without any more headaches!!