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Help Kohler 25 Fuel System????

Discussion in 'Lawn Mowing' started by MOW ED, Apr 3, 2000.

  1. MOW ED

    MOW ED LawnSite Fanatic
    Messages: 5,028

    I believe that I have a bad Kohler 25hp engine. In fact I know I do. Two major repairs in the first 200 hours both covered by warranty (scored cylinder and the dreaded blown head gasket). <br>Now my problem is the mower starts and will idle fine but after it heats up 20 minutes or so it stutters and looses power especially when under load (mowing) what could be wrong?<br>I changed fuel filters and flushed and cleaned the gas tank but the same still happens and it is always after it warms up.<br>Is it the fule pump or dirt or what I'm not real good at the technical mechanical aspect but I know something is wrong.<br>Will someone help, I'm in the middle of big time dethatch season. thanks, ed
  2. osc

    osc LawnSite Senior Member
    Messages: 502

    This engine has a fuel solenoid on the bottom of the bowl on the carburator. Possibly, you have a relay going bad, I think there is two of them. To find out if this problem originates from electricity, carefully take a wire and attatch it to the positive terminal on the battery and touch the bottom electrode of the fuel solenoid. Do this when the motor is acting up and if the engine smoothes out then you know the fuel solenoid is not getting enough juice. It is possible that the solenoid itself is bad which would not reveal itself in this test. <br>To check fuel solenoid, turn engine off and touch fuel solenoid with the wire that you attatched to the pos. terminal on battery. You should be able to hear a click when you touch it. If no click, then it's bad. If click then probably is good.<br>Relays generally act up when engine heats up.<br>If your battery is not being charged then a bad relay is more than likely the problem. It may take a while for this problem to show up, especially if you have a new battery. Only trouble with this senario is that Kohlor owns what is on the engine, not the wiring harness or anything on back. That is done by whatever machine this motor is mounted to. That can be a problem when trying to find help. Small shops may not have wiring scematics for your machine.<p>More than likely your problem is electrical unless the previous repairs were not done correctly.<br>If your engine smokes then the cylinders are still bad. If you hear a loud whisping sound while motor is running, then it's a head or gasket. Either way the last guy to work on this machine may not have wired it back up right and fried something. I would start with him.<br>Good luck, I feel your pain.
  3. JJ Lawn

    JJ Lawn LawnSite Senior Member
    Messages: 350

    Mow ED, Just out of curiousity, what did your dealer do to fix the scored cylinder?<p>My understanding from my dealer and Kohler was that these 25hp engines CANNOT be rebuilt nor the cylinders honed because of the hard finish applied to them. My dealer replaced my engine when I had this problem. <p>Jim
  4. GrassMaster

    GrassMaster Senior Member
    Messages: 447

    Hello:<p>If you can't find anything wrong with the fuel solenoid & BTW OSC knows what he is talking about when giving instructions on trouble shooting the fuel solenoid.<p>LOL, I forgot what I was talking about. If you find out that the solenoid is working OK. Since the engine has been gone into 2 times already, I would check the intake & exhaust valves, also their clearence. <p>I'm sure this is a Over Head Valve engine & both repairs would effect the valves, so I would really consider checking into this further.<p>Please let us know what you find out?<p>----------<br>GrassMaster - Home: www.lawnservicing.com<br>My Start Up Page www.lawnservicing.com/startup/
  5. thelawnguy

    thelawnguy LawnSite Silver Member
    Messages: 2,411

    Sounds like the engines overheating. I would pull the shrouds just for the heck of it and make sure the fins arent plugged with grass or mouse nest. Also make sure the dealer replaced all the shrouds, one missing will cause the engine to overheat. What kind of mower is it on? If its on a ZTR, i.e., engines under the seat I can promise its almost always caked with grass and dust debris.<p>Bill
  6. osc

    osc LawnSite Senior Member
    Messages: 502

    Mow Ed:<br>What was the dealer's opinion on why the cylinders were scored? Did you use this machine last season during the drought?<br>A lot of engines ingested dirt because of the dusty conditions. In theory, the air filters should catch all the dirt and if clogged, the engine should quit running. What really happens is the choke effect and more dirt gets sucked into the intake at a high velocity. Thus, a sand paper effect on your cylinder walls.<br>Even if you don't change your filter, dirt should not get past it so the manufacturer is at fault. Always tell the dealer how well you've cared for your machine. Never take a machine in for service with dirty filters even if it only has 50 hours on it. Anything that is wrong will be your fault.<br>Anyhow, I was just curious as to what their opinion was.
  7. Alan

    Alan Member
    Messages: 1,185

    Don't eliminate the possibility of an ignition module going bad as it gets hot. I'd be inclined to look for a problem with ignition rather than fuel when a hot engine starts cutting out. Also it might be worht checking the fuel lines to be sure that they aren't getting hot enough to cause fuel boiling somewhere. Probably less likely than in ignition problem but it's another &quot;possible&quot;. My own 25 Kohler had the head gasket problem but nothing since then as gone wrong with it.
  8. OP
    MOW ED

    MOW ED LawnSite Fanatic
    Messages: 5,028

    As of last night the prliminary problem is &quot;electrical&quot;. The mechanic ordered coils. The coils are under the motor somewhere so I can anticipate a large $$ repair because he said the motor has to come out of the Walker to replace the coils. <br>On the appearance of dirt ingestion in my first big problem, I have a turbo 3 precleaner into a Donaldson air filter then a Kohler foam filter wrapped over a paper element. 25 to 50 hr maintenance on all and all connections and wingnuts were tight. Kohler looked at this and had no basis to turn me down. The repairs were fully covered.<br>The mechanic was not familiar with the recall bulletin (it wasn't out yet) for the head gasket when the first break happened sohe didn't change them. Of course I have a **** (excuse my french) motor and the head gasket blew a year later. I mow 2 days a week and have 558 hours on this thing and I'm really pissed that I didn't get a new motor, but that is in future correspondence to Kohler. I'll let you know whats up. My next motor will be ANYTHING but Kohler.
  9. Mow Ed wrote:<p>&gt;My next motor will be ANYTHING but Kohler. <br> <br>You can't discount the whole line of engines<br>because of the early problems of the 25 hp<br>models.<p>That would be like saying I am not going to<br>buy a new chevy P/U because of the handling<br>problems of the 1962 Corvair.<p>I have a CV-18 v-twin that's five years old and I<br>have not had one single problem. No oil, fuel, leaks etc. <p>IMHO it is best to wait a few years b/4 buying any new design so the mfg. can work<br>the bugs out of the unit.
  10. osc

    osc LawnSite Senior Member
    Messages: 502

    Both coils do not go bad at once. This dealer has no idea what the problem is. The coils would be bad cold or hot and I'll bet they don't even have them wired correctly. I've been there and done that with this problem on a kohlor 20 horse. The problem you now have is not a kohlor problem. It is in the wiring harness!<br>Talk to a Kohlor distributor directly. But of course, they will just tell you that it's not Kohlor, it's Walker or the the service dept. doing the work.<br>Are you saying though, that dirt ingestion indeed has been an issue?<br>All of the manufacturers have had a problem with cylinder walls because of 1999 drought. None of them really want to own up to their part, which is questionable to some. <br>If you mow in a sand storm in Saudi Arabia, does that void the warranty? I dunno but your dealer is going to say it does. Last year was like a sand storm for us.

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