Vacuum or overflow tube? Usually when that happens the needle sticks wide open from the crap in it and floods the motor or pees out the overflow. Either way glad you figured it out!
Well...I thought I had this fixed.. but I was wrong. It ran like dog chit the last time I mowed and I decided to take another crack at it today. Background info that makes sense later....There has always been some oil leaking on the right hand side of the motor...I thought it was either from the crappy ez drain thing or the oil temp/level sending unit and it hasn't been a priority to fix. Today I decided to bench test the coils per the manual to rule out a spark issue. After I pulled the shroud I noticed the left bank was completely caked in dirt and oil. The oil cooler was packed on the back side. The whole thing looked like a crime scene once I got the covers off. The right coil was also completely caked in junk...even the surface facing the magnet on the flywheel. I have a failed oil cooler hose that has quietly been leaking oil and it built up just enough to interfere when the engine got hot. All the oil and grit on the coil probably made it hold extra heat too. That's my theory anyway. Couldn't test it because I broke a nipple off my fuel pump...doh. Going to pick up some hose and a new fuel pump tomorrow and see if that works. FYI.....I think they have gorillas at the factory assigned to torqing down the little Allen screws that hold the flywheel screen on. They were at least 463 ft lb. Took me the better part of 30 minutes to get one of them out.
I'd check your valve clearance while you have it ripped down a bit. The exhaust side gets out of wack since these engines are run on WOT a lot.
Got everything put back together last night but it was too dark to test. Mowing tonight. Hope this fixed it.
Just mowed. Started off normal. After 10 minutes it started sputtering and backfiring constantly...but not severely. I decided to keep going and the last 20 minutes it ran like a champ.
Same thing again this week. Runs good, runs real bad, run good. Runs bad = down on power, sputtering, backfiring, can't hold RPMs for a few seconds then runs normal for a few, repeat. Any ideas anyone?
What does the back of the key switch look like? Rust, corrosion, loose or movable terminals, or burnt looking? I'm assuming this engine has a fuel shutoff solenoid in the carb? Could be loosing power/voltage when it warms up and allowing it to stop or slow fuel delivery.
check the main ground......this happens on scags with kawi engine...usually were it bolts to the block
Main ground on the block appear tight and didn't have any corrosion. It did have some oil on it. I cleaned it up real good and put it back together. the wire for the oil sensor also had a lot of oil at the spade connection so I cleaned it up too.
Found this link for a slightly smaller engine than yours but some of the testing info would be similar. http://www.kawasaki.com/kengine/Eng...093-03_FR730V_FS730V_FX730V_English_eBook.pdf Not sure if it was mentioned or tried yet but did you try cracking the fuel tank cap when it starts acting up?
Update: Mowed last Sunday and it ran awful. Bench tested the coils and they both checked out OK cold and borderline warm. Decided to just replace them both. Ran it for a while tonight and it should have ran poorly but didn't. Think I got it whipped.
