Workhorse ST350 Won't Rev Up and Move

[trig123]

Originally Posted by Futility Vehicle

The fuel pickup apparatus seems to be pretty cheaply made, and mine is not in great shape. I don't know why the cart would run well cold and then bog down when hot, though.

The fuel filter always seems to be mostly full of air. Is that normal?

That is normal

[Futility Vehicle]

I don't know what the compression is. The engine could use a rebuild, but it pulls and runs fine before the fuel chokes off, so it's obviously making power.

[trig123]

Originally Posted by Futility Vehicle

I don't know what the compression is. The engine could use a rebuild, but it pulls and runs fine before the fuel chokes off, so it's obviously making power.

I can't help you anymore without knowing the answers to the questions I asked you. Good luck.

[Futility Vehicle]

I can get back to you when I've checked the charge voltage and tried it without an air filter. The compression will take more time. Thanks.

[Futility Vehicle]

The cart runs fine with no air filter. The filter doesn't look very dirty. What's the next step?

[Futility Vehicle]

Wondering if the Chinese jet is too big. Maybe I could take the jet out of the OEM carb and put it in the new one.

[JPonLKN]

Well, I went back and re-read the entire thread.

If it runs good with no air filter, you may have solved your own question as you may be getting too much gas for the amount of air when the filter is installed. They are air/fuel sensitive.

First step for me would be to swap both the main jet and tube from the old carb into the china carb, and the jet under the screw on top of the carb. Might be all there is to it.

If that doesn't work, it sounds like you had a temp repair on the old carb. Try it again and see if it will work. If it works, obviously CCP sold you junk that can't be made to work, and you know what to do...either get a OEM carb, or find a way to permanently repair that float pin post.

In either case above, suspect it will run and then die. I am guessing you have a bad fuel pump. I suspect the float pin support post may have been broken and the carb still work adequately. All it does is shut off the fuel to the carb, so it would be backfiring when off throttle, but would still run. The bad side is that you could get gas in the block by turning it over and it not firing, so I wouldn't leave it that way. Gas would just pump through the carb past the needle valve, assuming the float couldn't close it.

Have you changed your oil? If your oil is thinned with gas, ie: got gas into the case after flowing through the carb, you could have a bigger problem, and would explain why it runs poorly once it heats up.

Also, have you checked your valve lash? .004, as has been said before. It is very likely that that broken carb was working and its just time to adjust those valves.

[trig123]

Originally Posted by Futility Vehicle

The cart runs fine with no air filter. The filter doesn't look very dirty. What's the next step?

Does your air filter box have any hoses that run to the front of the cart connected to it ?
I have seen these plugged up. One that had been sitting for a while actually had a bird next in it, but again I am not sure which air box you got ?
Round or Rectangle ? I would guess the round one on the ST350 ?

[Futility Vehicle]

I have a rectangular box that goes to a vent under the cart's seat. I can yank the hose and make sure it's clear. I don't think mice could get into it, but they have surprised me before.

I kind of wonder if the 295cc carb would have worked better. I hate to suggest that a vendor of $20 Chinese carbs might make a mistake, though.

The old carb is history. Maybe I could use a TIG torch to build up a new post to hold the float pin, but when you start talking about measures like that, I suppose it's best to find an OEM replacement somewhere.

Chinese carbs work great in my other equipment. My winning streak came to an abrupt halt with the cart.

[Futility Vehicle]

I took the main jet out of the old carb and compared it to the new one. It was definitely smaller. I put the old main jet in the new carb. Now the cart runs, even when warmed up.

It looks like the way to make a Chinese carb work is to use your old jet or buy an OEM jet when you get your Chinese carb. Or maybe the 295cc carb is actually the correct size for the 350cc engine.

Now I'm starting to wonder if I actually have a 350cc engine. I thought I checked. Anyway, the cart runs.

Thanks for all the help. The suggestion to take the air filter off showed me what was wrong.