25 Hp Kohler Gravely... black smoke under load.. loss of power??

michaelhawkins1

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  • / 25 Hp Kohler Gravely... black smoke under load.. loss of power??
Don't buy a new carb yet. I think it just might be the fuel solenoid, telling you what's wrong. Just reread the entire post twice then remembered a problem I had a couple of years ago. Check the wiring going to the fuel solenoid and. I think if you look and feel carefully you are going to find a cracked or partially broken wire. What is happening is the wire will short when you hit a bump or turn. When this happens it will kill the ignition circuit for an instant, meaning no spark. Then it will reconnect and have spark. During the no spark period some raw fuel will enter the cylinder causing a rich mixture, and then when the plug fires a lot of black smoke. It will also backfire with this problem, because the rich fuel is still burning when the exhaust valve opens. You will have to look very closely with your fingers. Go slow and be patient. Go luck.
Hey Rivets... this post is almost to a Tee what mine is doing. (Exmark 25hp Kohler command) just started doing this a week ago, Slight black smoke under load, will backfire occasionally, Loss of power drastically starting to mow anything. will sutter when I hit a bump and puff a black smoke like it's over full. still has problems starting have to choke and then quickly release choke.
Here is what I've done so far... new plugs, air filter, fuel pump, fuel lines. I'm thinking of getting a new carb 30.00, that would take care of solenoid, float and highspeed jet. I'm really struggling here and would appreciate any advice, thanks Michael
 

michaelhawkins1

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  • / 25 Hp Kohler Gravely... black smoke under load.. loss of power??
OK... I gotta give an update..

Checked over the entire engine looking for a frayed/broken wire ect.. at first no luck.. So I was able to find a friend who had an identical engine (which ran fine) who was willing to swap carbs to eliminate the whole carb issue.. Swapped the carbs.. still poping and backfiring... Grrrrr.... So we decided to pull the valve covers and check the valve clearance... There was zero clearance from the rocker to the valve stem..?? (I also need to find out how to check the valve clearance cuz we couldnt fit the smallest size feeler between rocker and valve anywhere in the stoke, tried TDC... no gap at all.. then tried everywhere in stoke) So we pissed around and kinda noticed that one of the springs on the intake valve on one side wasnt compressing the same as the other side?? We removed the rocker and pushrod and swapped the rods with the exhaust.. (both rods looked identical). (not sure why we did that).... While We had it apart I was looking closely for a broken wire ect... I found a taped wire that would normally rest on the engine cover, I pulled the tape off and it was frayed, wire was still intact but insulation was peeled?? We cut it and put a butt connector with shrink wrap. It was a purple wire from the voltage regulator... So after all this we put everything back and fired the engine. I cut for approx 40 min no backfiring??? I then cut again that night for another hr and no backfiring? "Touch wood" engine runs better than ever?
WTF?? ... .. We never found a smoking gun.... I guess if the backfiring returns it is a valve issue... if it doesnt it was the wire?? I dont feel comfortable... I wish we found a smoking gun! Then Id know we nailed it....

Any comments....

Thanks for all the help!
Hey gunner... could you give me an update on your situation... it sounds Identical to mine. thanks Michael
 

Rivets

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  • / 25 Hp Kohler Gravely... black smoke under load.. loss of power??
Did you read gunners post #9. Start there and then post back. Do you know this thread is 9 years old, I doubt gunner is around any more.
 
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