Workhorse ST350 Won't Rev Up and Move

[Futility Vehicle]

I have a Workhorse ST 350. The old carb is beyond repair due to an accident. I put a Chinese carb on it, and it ran fine for a couple of outings. Then the power went down to the point where the engine wouldn't turn the crank fast enough to get the cart moving.

When I remove the carb and use a sonic cleaner on it, it works better for a few seconds. Then it slows to a crawl or stops.

I also replaced the fuel filter and the lines between the tank and fuel pump.

What's the most likely problem? I have a number of Chinese carbs for things like chainsaws, and they work fine, so it's hard for me to believe this carb can't be made to work.

[JPonLKN]

If it isn't turning over fast enough to fire up, my guess is either the battery or starter generator, or possibly loose connection somewhere, not the carb.

[Futility Vehicle]

It fires up. It just won't rev high enough to engage the rear wheels.

[JPonLKN]

Have you adjusted the valve lash? It is amazing how much it affects running ability. There is a sticky in the tech section on how to.

[Futility Vehicle]

I know it's the carb or something else on the intake side. Everything was fine until the old carb broke.

[crash12888]

Is there a plastic insulator between the carb and block? I can't remember but check for cracks.
Give a shot of starting fluid between the carb and block while cranking, if it starts you have a vacuum leak.
Also check the pulse line from the fuel pump back to the block for cracks or loose connection.

[crash12888]

and I would still check valve lash, .004 cold on all 4 valves.

[StoveBolt]

Originally Posted by Futility Vehicle

I know it's the carb or something else on the intake side. Everything was fine until the old carb broke.

Will it rev up with a little starter fluid? if not look some where else.

[JPonLKN]

Originally Posted by Futility Vehicle

I have a Workhorse ST 350. The old carb is beyond repair due to an accident. I put a Chinese carb on it, and it ran fine for a couple of outings. Then the power went down to the point where the engine wouldn't turn the crank fast enough to get the cart moving.

When I remove the carb and use a sonic cleaner on it, it works better for a few seconds. Then it slows to a crawl or stops.

I also replaced the fuel filter and the lines between the tank and fuel pump.

What's the most likely problem? I have a number of Chinese carbs for things like chainsaws, and they work fine, so it's hard for me to believe this carb can't be made to work.

I'm curious, when you say you use a sonic cleaner on it, are you pulling both the main jet and tube out, and the pilot jet out prior to cleaning? Adjusted the float in the carb when done? You didn't say what kind of accident. Is it possible it affected your fuel pump as well? You replaced the lines and filter, have you pulled the fuel line free from the carb and turned over the motor? You should get a regular flow of fuel. If not, could be the pump, or maybe the plastic pick up tube at the tank has a crack allowing air and limiting fuel flow.

[crash12888]

Good point JP, a lot of times we focus to much on what is said rather than going back and eliminating issues with the basic test procedures.