17.5 Kohler engine problems

[jerkputter123]

I had a riding mower donated to me as the owner had no room to keep it. Craftsman with 17.5 Kohler.
Family-SKH426U1G2RB
Model CV16S
SPEC NO 43520
DISPL (CC) 426
Serial # 29111003933
The engine was running fine but had steering issues. I was very careful to make sure I didn't get the engine wet when I had to pressure wash under gas tank to try and see what was wrong with steering. It had old grass at least a foot high on top of steering gears.
It will now run for sometimes 2 minutes and the next time 7 or 8 minutes and then start to explode out the muffler and then die. It is very loud when it does this sounding like it's going to blow the muffler off.
I can let it cool and it runs good again. The time frame is different on when it starts the loud explosion type noise but it will do it.
The 20 amp fuse on right side under gas tank area got real hot and blew when I first started it after pressure washing. It looked like it was almost melted. The volt meter also burned out. It was working yesterday I know but now stuck all the way to the right and won't move.
It does sound like the coil causing this but the person who had this mower said he never once had any issues with this type problem since he first bought it in 2001. I thought maybe the regulator was detective because it was charging around 15.5 volts and the ignition switch wires were really hot also I installed a used regulator, one I got from a friend and now it shows 13.5 volts on battery at wide open throttle.
Any idea what has happened to this engine ? My cousin was the owner for the last 18 years and like I said he said the deck and tires were just too far gone and he wanted a newer mower so i got it. You can tell when its going to start the exploding because it will start off trying to quit but then catch up again for a few seconds and then boom. HELP/

[Luffydog]

I heard I of this happening back about 7 years ago your post rings a bell but can't remember what was going on with it. Seems like it was over fueling and not firing and then it got fire or spark I should say and the unburnt gas in the muffler explodes or ignited then causing the noise you are talking about best I can remember it blew the exhaust out. Maybe someone else will remember this issue better and have a better thought. I think this about the third time I have heard about this issue. It would good to know what the cause is for sure. Keep us posted. Sorry maybe it will come back
To mind if not others will chime in soon to help

[jerkputter123]

Thanks, hope it comes back to you.

I removed the spark plug and it is burning lean it appears. I installed another new spark plug just in case the new one I replaced the first part the week was bad. No such luck.

The original voltage regulator seems to bog down the engine when I plug the wires on it. I thought maybe it was overcharging causing the wires on ignition switch and fuse holder to get hot so that is why I tired a different one. When I connected my volt meter to battery with original VR installed it did show almost 15 volts which is a tad too much I would think. The one I borrowed from a friend who owns a small engine shop told me to try and see but he was sort of baffled on what the problem was himself.

I can't say for sure how long before it will start the loud exploding . It is so loud I think my ears were ringing. Almost like a shotgun being shot. All the dogs have left the scene

I can leave it running and go sit at my computer. I can tell when it going to start this mess because I hear that one little miss and then it soon starts. Yesterday I thought maybe I was on to something because it ran for 20 minutes without an issue and then I heard that slight miss and before I could get to it when the exploding started. I am almost afraid to try it again because I actually think something is going to damage this engine. I tested the fire as soon as I have the time to shut it off and it has nice spark with my tester.

I had cranked this mower several times since I acquired it but don't remember how long I ran it. I know the issue seem to start right after I used the pressure washer on it. I work on things everyday ( ezgo gas carts ) and if I do pressure washer something I am very careful to cover electrical things with plastic bags which I did with this mower the best I could.

My cousin and I grew up together and he would have told me the truth if this issue was there when he brought it to me. I only need a shop mower to cut the back part of my shop which is about 1/2 acre. My grass looks as good as most homes so I need a cheap mower to do the job as my old 1991 Murray is about bit the dust

[bgsengine]

I'd suggest doing a voltage drop test on the ground side - almost sounds like a grounding problem what with wires getting hot - does engine bolt securely to frame, and battery ground have good connection to frame all the way to engine? With a bad ground, your fuel solenoid may be dropping out, leaning things out to the misfire.. your pressure washing job may have disturbed a ground wire or electrical connector (check packard terminals for any possibly corroded or poor connecting terminals, corrosion that was allowing ground that might have gotten washed away, etc)

[KE4AVB]

As BGS said check all connections first due the water ingress.

To me it sounds like a misfiring spark that failing when hot under compression or the overvoltage has screwed up the DSAI module. That module has been replace with an upgrade kit where everything is now inside the new coil.

But as you things got overheated electrically.

[jerkputter123]

I checked and cleaned all ground connections. I did the voltage drop test and all is good. Getting 12.5 volts at battery and when I touch most any place on ground part of frame and engine.
Now I thought maybe this fixed it. It ran for exactly 11 minutes and the exploding started again. I quickly turned it off. I also removed the harness going under tank where I pressure washed and they were good. No corrosion and the black wire in harness when I touch it to my meter and the other to positive side of battery is 12.5 volts.

[jerkputter123]

As BGS said check all connections first due the water ingress.

To me it sounds like a misfiring spark that failing when hot under compression or the overvoltage has screwed up the DSAI module. That module has been replace with an upgrade kit where everything is now inside the new coil.

But as you things got overheated electrically.

That sounds like what might have happened but I was very careful when I cleaned it protecting with plastic bags where I could. The 20 amp fuse holder connection is not hot now that I replaced the V/R . If I had thought about it I would have removed the regulator before I started the cleaning but I really never got any water in that area. I have cleaned many things over my years with pressure washers and this is a first. I do think it is something I did though because he told me cut grass with this mower just before he brought it to my shop. Dang

[jerkputter123]

I'd suggest doing a voltage drop test on the ground side - almost sounds like a grounding problem what with wires getting hot - does engine bolt securely to frame, and battery ground have good connection to frame all the way to engine? With a bad ground, your fuel solenoid may be dropping out, leaning things out to the misfire.. your pressure washing job may have disturbed a ground wire or electrical connector (check packard terminals for any possibly corroded or poor connecting terminals, corrosion that was allowing ground that might have gotten washed away, etc)

Would a bad fuel solenoid cause this issue ? and is there a way to disconnect this thing. The owner told me this mower always had to be choked to start. I noticed that also. It would be idling fine before it gets hot and starts the backfiring and I turn it off. I always have to choke it to get it to start. Seems like it should crank right back without the choke if it has been running for 7 or 8 minutes ?>?

[KE4AVB]

That sounds like what might have happened but I was very careful when I cleaned it protecting with plastic bags where I could. The 20 amp fuse holder connection is not hot now that I replaced the V/R . If I had thought about it I would have removed the regulator before I started the cleaning but I really never got any water in that area. I have cleaned many things over my years with pressure washers and this is a first. I do think it is something I did though because he told me cut grass with this mower just before he brought it to my shop. Dang

I get that comment a lot just got what I see. I had mower I recently rebuilt the spindles on that the customer said it was plowing up the yard and that I returned it that way. Upon going though a translator she admitted she cut her lawn twice without a problem after I returned it. Come to find out the deck was severely bent and it took me two hours of pounding to get the RH blade and spindle back level. She griped so much I just charge for the pick and delivery. Then she was informed not to bring it back as I wasn't doing any further work for her. That what I get for doing work for her at parts cost and half labor. She I ought to do it for free. Let's see if another shop going to do it for cheap.

Anyway I lookup which solenoid you are using on that engine and you can remove it temporary and replace it with an appropriate size screw. Note: This is for test purposes only.

As having to choke I have several engines that require this. I even have one Kohler here that smokes every time it is crank up; has been doing this from day one.

[jerkputter123]

Thanks for the help. I am willing to try anything but I am leaning toward ignition problems because it has to get hot before this happens.

I also think it happened after I washed it but I might be wrong. Almost like it gets out of time when hot.