LT1000 surging

bkenobi · Nov 7, 2023

After getting the starter sorted out, I ran the mower for around 30 minutes to confirm the charging system was keeping the battery topped off. When finished mowing the section, I throttled down a bit to get the deck washer and noticed that the engine was surging/hunting. For reference, this mower has not let me run with the choke all the way disabled so I assumed there was something going on with the carburetor that would need addressing at some point.

I pulled the top of the carb off and it looks pretty clean inside. The gasket was still in good condition so hopefully it will seal again on reinstall. In regards to the valves, I ordered a set of tip cleaning wires from Amazon that just arrived but wondering if I should just use acetone or some other carb specific cleaner first? I don't know how tight the tolerance is on the jets so without knowing the size it should be, I'm hesitant to use mechanical means to clean the port. The air box and filter looked clean so I don't see it as an air issue which obviously leaves fuel supply (jets). I have pictures of the carb so it can be identified if it matters.

tomplum · Nov 7, 2023

Basically look for wear on the float valve whilst it is apart. The little holes in the body, kinda three in a row - the tiniest has to be cleaned. A wire from a brush is fine. The main is through the bowl nut. Just use whatever jet spray you have and it will be fine. 3 screw fuel pump or 4?

bkenobi · Nov 7, 2023

It's one of the 3 screw pumps. I thought it was a fixed idle jet but when i removed the screw i realized it was adjustable. I cleaned all the ports and jets. Bowl looked clean but sprayed some carb cleaner in anyway. The gaskets looked ok so initially reinstalled to test. While it fires up strong and i can push the choke in (after adjusting idle screw a little), the gasket between the upper and lower was leaking by the pump so ill have to get a new one.

At this point, its looking pretty solid!

bkenobi · Nov 7, 2023

I do wonder if i should take the time to clean the fuel pump now that I'm working on it. Is that something that typically needs servicing unless it's showing certain signs?

tomplum · Nov 8, 2023

bkenobi said:
I do wonder if i should take the time to clean the fuel pump now that I'm working on it. Is that something that typically needs servicing unless it's showing certain signs?

They are quite dependable really. It won't need cleaning. Any pump issues you would replace the diaphragm. If you do take it apart, do so cautiously. Couple of little springs to lose.

bkenobi · Nov 8, 2023

I don't know of any issues with it, so I'll leave it alone until/unless that changes.

5030 · Nov 8, 2023

bkenobi said:
After getting the starter sorted out, I ran the mower for around 30 minutes to confirm the charging system was keeping the battery topped off. When finished mowing the section, I throttled down a bit to get the deck washer and noticed that the engine was surging/hunting. For reference, this mower has not let me run with the choke all the way disabled so I assumed there was something going on with the carburetor that would need addressing at some point.

I pulled the top of the carb off and it looks pretty clean inside. The gasket was still in good condition so hopefully it will seal again on reinstall. In regards to the valves, I ordered a set of tip cleaning wires from Amazon that just arrived but wondering if I should just use acetone or some other carb specific cleaner first? I don't know how tight the tolerance is on the jets so without knowing the size it should be, I'm hesitant to use mechanical means to clean the port. The air box and filter looked clean so I don't see it as an air issue which obviously leaves fuel supply (jets). I have pictures of the carb so it can be identified if it matters.

Think I said previously, go to the auto parts store (Autozone and NAPA) sells it... Berrymans B12 Chem tool in a gallon can (comes with a strainer basket) and take the carb apart, jets out, idle and main jet screw removed (remember to count the turns before removing) and soak it it the Chem Tool overnight and then remove the parts from the basket and rinse carefully with hot water and let dry and reassemble, The B12 will remove any and all stuff in the carb, I guarantee it. I use it in my heated ultrasonic cleaner but it works cold as well. heated is faster, I can do a carb in 15 minutes. Cold takes overnight. Best part is you can put the lid back on and use it over and over. Good stuff. Gumout also makes a similar solvent but my preference is B12 Chemtool.

'Mustie' on You Tube uses it in his ultrasonic cleaner, I suggest you watch some of his video's.

DO NOT use cleaning wires in the carb, chances are you'll ruin it.