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P51D · Aug 27, 2007, 09:35 AM

I have a 2003 John Deere LT 160 with a single cylinder 16HP Kohler. It was mowing fine on Saturday. On Sunday, when I started it, it backfired several times, finally started, and it now runs very poorly. With the throttle at full, it doesn't develop anywhere near full rpm, actually seems closer to idle rpm. And seems very loud at that. As I slowly close the throttle, RPMs actually pick up a little, but then decrease as throttle is closed further. If throttle closed to idle, engine will die. If throttle is advanced into choke range, engine bogs and dies. Any load on engine (e.g. engaging mower clutch) will pretty much kill it.

Fuel pump is delivering fuel. Pulled the plug, and it was dark brown, with a little carbon on it. I cleaned it up and gapped it to 0.040", per the book.

Any ideas?

P51D · Aug 27, 2007, 09:41 AM

Oh yeah. I also cleaned the air filter, and started it without the filter. No help. Engine has a little over 100 hrs on it.

esquire1 · Aug 27, 2007, 01:54 PM

Gap should be 30

P51D · Aug 28, 2007, 05:04 AM

Thanks, Esquire1. I'll re-check what the manual says, but I'm pretty sure it specified 0.040".

I also checked the compression last night, and it was over 150, which seems very strong.

I'm starting to suspect timing. What could cause timing to suddenly be off drastically? Anything to look for?

I've never set timing for a small engine. Any tips?

THANKS

P51D

MOWERMAN2468 · Aug 28, 2007, 05:51 PM

Check the governor springs. As far as the timing, you only need to check one thing, the flywheel key. To loose timing the flywheel key can shear. Yes, the cam shaft and crank shaft have timing marks, but if they were to be off, you would have serious expense on repairs. The most common loose of timing is the flywheel key.

P51D · Aug 28, 2007, 06:35 PM

Thank you, MowerMan. P51D

MOWERMAN2468 · Aug 30, 2007, 08:18 PM

Did you get it going?

P51D · Sep 1, 2007, 04:38 AM

Mowerman - I had to bring it in to the shop. I pulled the fan housing, etc. to see if I could get a good look at the flywheel key, but no joy. Apparently the keyway slot is not cut all the way to the visible end (of either the flywheel or crank, I forget). But judging from where the magnet on the flywheel was (about 5 o'clock) when I had the piston at what I thought was TDC, I think the key is sheered.

Thanks for following up, and I'll let you know what the shop finds.

MOWERMAN2468 · Sep 1, 2007, 07:07 PM

Oww, that is going to cost probably around $40. Including labor. Better luck next time. Did you remove the large nut and washer at the top of the crankshaft to inspect? Which it doesn't matter now, cause you have it in the shop. But next time we may can help you better. Have a nice day.

P51D · Sep 9, 2007, 06:03 AM

Mowerman - as you suspected, the flywheel key was shorn. Thanks for your help.

P51D

MOWERMAN2468 · Sep 9, 2007, 06:13 AM

Umm, glad you got it going, but did you fix it yourself, or did you have to carry it to the shop? And if it did go to the shop, was I pretty well in the price range of the charges? Just curious on the last sentence.

P51D · Oct 6, 2007, 05:58 AM

Mowerman - I just got the bill, but they didn't break it down. I had them do a couple of other things while it was in the shop, so I don't exactly what the flywheel key repair cost. Thanks for your help.

MOWERMAN2468 · Oct 6, 2007, 06:49 AM

o.k. at least you can mow again huh. Good job, you done well, sometimes though taking it to a shop is about the only option.

ajshoe · Jul 11, 2010, 03:05 PM

Check carb solenoid for loose rubber stop. This is a design flaw of this carb. Rubber stop comes off and doesn't allow gas to enter carb. John