Archive through June 16, 2015

[elamott]

129 Engine problems again/yet
I posted a question a little while ago regarding my 129 engine that would bog down like it had no power and eventually stop. I had comments regarding the coil. I tested the coil and it seemed bad so I replaced it. The problem came back. I then checked the resistance on the coil wire and it was bouncing all over, so I found a old spark plug wire and put that on. Still same problem.
When it bogs down and I stop everything and put it to an idle it runs ok. When I give it more gas it does not run. I am starting to think fuel. The settlement bowl was clean and the tank seems clean. If there was a fuel filter I would guess that, but there is none. I am thinking about pulling out the main jet to see there is some dirt in there. Another thing that adds to it is if I leave the engine cool off it runs fine for a while(10 to 15 minutes) then it starts to act up. Also when it is running bad I can see smoke coming out to the air breather. I don't know if this means anything but I thought I would mention it.
I am running out of ideas. Any thoughts from anyone greatly appreciated.
Thanks for any help
Earl LaMott

 

[dschwandt]

Earl, I'm thinking sticky valve. Do you run anything in the fuel like MMO??

Also, have you serviced/de-carboned the head recently....or ever??

 

[mfrade]

Earl L., on some fuel tanks there is a small fine screen at the outlet fitting. You may be able to get a look at it inside.. or pull the fitting and see if it's there and what condition.

 

[elamott]

129 engine problems again/yet

Mike and David thanks for the comments.
I have not put in any additives. Would sticky valves start after the engine gets hot. When the engine is cold it runs great.
I did try and look at the screen in the tank and what I can see it looks clean. The tank looks spotless inside.
Something happens when it gets hot it will run perfect for short time. (10, 15, 20 minutes)
I am thinking something inside. Could something be binding when it gets hot. I rebuilt the engine in December of 2009 and it has run perfect up until last week.
I am going to check the fuel line yet but otherwise I do not have any other ideas.
Thoughts appreciated
Earl

 

[kfreeman]

Earl,

I am surprised that no has mentioned the air vent in the fuel cap.

My neighbor's brother just had the same symptoms on a JD lawn mower that is about 9 years old. Cleaned out the vent, and it runs fine.

 

[kmcconaughey]

Earl, yes the exhaust valve can stick when it gets hot and then release when it cools down. I went back and read your earlier posts and you said you have the Points Saver installed so no condenser. While I have not heard of a failing Points Saver, it could be possible. Any chance you have a condenser setup from a spare that you could swap in as a test? I would do something like that long before I would go after the exhaust valves. Also as mentioned by Ken below, check the gas cap vent. Also make sure there is no blockage of any kind in the fuel system, filters. screen, so on.

 

[jchamberlin]

Earl: As someone who has suffered from exhaust valve problems and fuel line problems, I have some thoughts on your predicament.

(1) Sticking exhaust valves tend to be intermittent irritants, as in, <u>NOT</u> EVERY TIME you mow, but just 1 or 2 times out of three that you use the equipment, and the problem gets worse, or more frequent when it is hot outside. Basically, the issue is too much heat in the wrong place causing the valve stem to stick so badly in the guide that the spring cannot overcome it. When the head cools, the problem goes away. The tell-tale sign that the valve is stuck is that the engine turns over much faster and/or easier when the valve is stuck open. The reason additives are mentioned as a cure is that they dissolve the varnish built up on the valve stem and allow the stem to move freely enough that the spring can close it. I have found that the IH Low Ash oil is an excellent antidote to the problem and recommend it highly, although I am currently running 10W-30 full synthetic without a problem (I drained the pan before checking my supply of Low Ash

).

(1) Fuel system problems can also be intermittent, depending on what is sloshing where, but the vent cap, which is a good candidate for causing your symptoms, would occur EVERY TIME you run your engine. If you are experiencing the problem every time, at a predictable interval, I would suspect the problem related to the engine's need to "breathe" beyond just sucking in air.

(3) If the smoking from the breather is a new phenomenon, and not something which has been going on for some time before the current issue developed, then I wouldn't worry about it. However, if the smoke from the breather is something new which coincided with your stalling out problem, then I would consider it a valuable clue. A lot of smoke from the crank case would indicate severe back pressure.

How is your muffler?

If the muffler is stopped up the "exhaust" can't and may be finding its way into the crank case.

Like the gas vent problem, a stopped-up muffler would shut the engine down at a predictable interval EVERY TIME you run it.

Just my two cents.

Good luck, I'm sure you'll figure it out. If you rebuilt it in 2009, and it is still running, you're not a bad mechanic.

 

[aaytay]

Earl-
It is possible that you're experiencing a failing ignition switch or possibly the wire from the switch to the coil is failing as things warm up. You may want to try hot-wiring the ignition by bypassing the ignition switch to rule that out. (Also, check that ignition wire with an ohm-meter or test light. Give the wire a good shake while you're testing it.)

I know we're throwing a lot of different options for this issue at you. Start with the easy solutions first. I've found that 98% of the cub-problems I have had are usually the result of a SIMPLE issue.

Good luck and keep us posted!

 

[glippert]

Wow, a lot of good ideas for Earl to use in troubleshooting his problem. Jeremiah, I really appreciate your explanation of each potential problem and solution. Even a dummy like me can understand them!

Thanks to Charlie and all the sponsors for this site - I learn something new nearly every day. (Not to mention the entertainment value when sparks occasionally fly!)

 

[cmiracle]

Earl- those are the exact same symptoms I had when I hooked my new coil up wrong in the 1200 last summer...

Check your wiring to the coil? Condenser and the points wire goes to the negative terminal on the coil.