LT1000 - Misfires and stalls out

[SeniorCitizen]

I recently replaced the carb, oil, oil filter, air filter, and spark plug on my LT1000. It is misfiring and then stalls out. Anyone have any suggestions on what to try?

Try a Champion plug .

 

[Auto Doc's]

OK - I was able to clean (for the most part) what I think is the rocker cover & attached are a couple of pics.
I think the model is - 2 followed by some strange symbol, 3H07
Type - 0399 E1
Code - 050607ZE

Fuel is not old and I use rec fuel only, so I don't think there is water in fuel. Should I go ahead and drain fuel in case there are bugs, dirt or grass clippings causing problem? I looked in tank and it appears clean. Is the fuel nipple in the bottom of fuel tank?

Need to find the product information label on the chassis of the machine to figure out how yours is built.

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[sgkent]

I would verify that the choke is working properly. Would add some fuel line drier like Heet or another brand to the fuel and drain a little fuel out of the carb, and try it again. Certainly a new genuine and not counterfeit spark plug may help. If that fails, I would definitely adjust the valves to be sure they are still in spec. They expand as they heat up so if one or more is tight, heat can cause it to expand to where an engine runs poorly or dies. Also would use the original carb after checking the bowl for corrosion since the replacement did not help. While the valves are being adjusted, retorque the heads in case they are loose and losing compression. If that helps then prepare to pull them when you have time, check for warp and address as needed. When you put the old carb back on, let a little fuel flow into a glass jar - maybe 1/2 inch and see what it looks like. Also pay attention to how fast it flows. If your engine has a fuel pump, they wear out too and that can cause problems.

 

[GiLinFtLaud]

Changed the spark plug and started running like NEVER before. I noticed the gap on the spark plug was minimal which I found very odd. Mower ran GREAT for about 15 minutes and then started to want to stall. Waiting for it to cool down before checking spark plug (Champion) to see if gap was reduced.

Anyone have any ideas?

 

[Auto Doc's]

Pictures would help.

Do you have a tool to measure the plug gap? Plugs seldom come with the gap set correctly for your engine.

Is it excess black carbon buildup on the plug tip?

Nothing wrong with Champion plugs unless they are counterfeit.

Ran great for 15 minutes then started to stall? Is the fuel tank cap vented or is the tank vapor vent hose possibly plugged up by dirt or an insect nest.

 

[GiLinFtLaud]

Thanks - Attached is pic of plug; It looks fine. Do you know what the gap should be?

Tank vapor vent hose - Can you please describe where that is located?

 

[Auto Doc's]

I had to recheck Parts Tree. This model may not have had a vapor vent hose. The tank shown is in plain site placed ahead of the operator console? The fuel line connection comes out of the bottom and runs to the carburetor.

That plug shows to be burning very lean. This indicates a fuel starvation somewhere from the tank to possibly the carburetor. That or the intake mounting seal/gasket is no good.

Drain the tank and replace the line sections and filter would be my initial step. Verify that tank nipple at the bottom is perfectly clear. a fine chunk of debris or grass chaff can block these partially and is often hard to see.

Next, Flip the fuel cap upside down to look inside and make sure the inner rubber components are not breaking apart and falling into the tank. I have found this problem on a couple of older models over the years. A little piece of that rubber will get caught in a fuel line and interrupt the fuel flow at random times. That can be a hard one to figure out.

 

[GiLinFtLaud]

Thank you! I checked the gap and it was fine (.030); put it back in, checked the air filter, I checked and tightened the fuel tank cap (don't see any vapor line - just a small hole on top of fuel cap tank cap);

It started right away and idle'd perfectly. Ran it for a little and then it stalled as I was going up a slant. Started back up and continued to run fine. It seems to be fuel related when I'm at a slant. I replaced the fuel line when I replaced the carb as well as the fuel filter. running at sharp angles was previously not a problem.

I'm starting to think it could be the intake mounting seal/gasket!

 

[GiLinFtLaud]

I had to recheck Parts Tree. This model may not have had a vapor vent hose. The tank shown is in plain site placed ahead of the operator console? The fuel line connection comes out of the bottom and runs to the carburetor.

That plug shows to be burning very lean. This indicates a fuel starvation somewhere from the tank to possibly the carburetor. That or the intake mounting seal/gasket is no good.

Drain the tank and replace the line sections and filter would be my initial step. Verify that tank nipple at the bottom is perfectly clear. a fine chunk of debris or grass chaff can block these partially and is often hard to see.

Next, Flip the fuel cap upside down to look inside and make sure the inner rubber components are not breaking apart and falling into the tank. I have found this problem on a couple of older models over the years. A little piece of that rubber will get caught in a fuel line and interrupt the fuel flow at random times. That can be a hard one to figure out.

I also installed a cut off valve which I did not have before (see pic). Could it be it is restricting fuel whenever I am at any type of slant?

 

[Auto Doc's]

I forgot the mention the connector for the solenoid on the bottom of the carburetor. Gently move the connector from side to side and see if the engine acts up.

The pins on the harness connect tend to spread and lose proper connection over time.

If that solenoid is an aftermarket, they always have trouble with connector fit issues.