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Riding lawn mower carb problems

Its not a car question butttt…

we have a older riding lawn mower that until we fired it up today ran great, we started it up about a week ago and it was ok, but today we were useing it and it started cycling on the rpms. now it stalls after a few min, and will only start when we prime it.It is a yard pro with the 17 hp tucumsa moter. we took the carb off and cleaned it but it didn’t help does it need a new carb or what? thanks.

float level,air filt blocked,main jet,pilot jet(you know transition jet)you are missing air to match fuel or fuel to match carb? unlikely.

that help

I’m not familiar with that particular engine but a couple things to check. If the float is hung up closed it won’t allow fuel in the bowl so make sure the float moves freely. Also, my twin Briggs has a diaphram type fuel pump and if yours has a similar fuel pump, you may need a new diaphram. Check the parts list for the carb and look at the main jet, gaskets etc. Easiest is just get the carb kit and put new parts in while you’re at it. Also check for water in the fuel, plugged fuel filter, etc. You did turn the fuel on didn’t you? I tore my snow blower carb apart twice after an overhaul and finally discovered I didn’t turn the fuel on.

two thoughts.

when did you last put gas in it?

was it before the mower started running rough?

and have you checked the gas level?

although the carb may be a problem, if you haven’t put good gas in it (or the gas you put in was filled with crud) or if it is low on gas may outweigh any other info

Did you check for a plugged fuel filter? Does it have a float type carb or a diaphragm “pumper” type carb? MANY SME problems originate with contaminated fuel…

Sounds like the choke is sticking on, to me.

We checked all of the stuff you guys listed, it has good fresh gas, a clear fuel filter and the float is fine. we can’t seem to find the jet ajuster screws, but we checke and the choke is not sticking. It is a gravity fed fuel system so the pump is not in the picture. another thing is it will run (after we prime it) only if we have it on full choke.

sounds like the main jet or emulsion tube are plugged. Happens on engines sitting for a long time. Need to clean the orifices with a fine wire after pulling them. Carb cleaner rarely resolves it by itself.

i asked about the timing of when this started, compared to when you put gas in it.

i have found when a particular fuel related problem crops up, it is most often just after a refueling, indicating something was in the fuel, or the funnel used to fill up.

since you describe the ‘runs on full choke’ scenario, that would indicate a fuel supply problem.

i would change the fuel filter, and then go after the carb. cleaning and new gaskets are probably not going to cost much, just the aggravation of having to take apart something as simple as this is a pesky time eater.

have you cranked it while totally blocking the air intake? i have found that will force the gas through the jets and seems to clean them out. be aware the force created by the suction is pretty strong and you don’t want to get a hand stuck in the intake.

Aha, so actually, your problem is that it dies without having it on full choke. The surging and such is an effect of having the choke on.

This is certainly a fuel delivery problem. I think ripstop has it right.

The main jet on these carburators is usually in the bolt that holds the fuel bowl to the body of the carburator. Visualizing the main jet is hard to do as it goes down the center of the bolt. If you slip something white in the cross drilled hole you should be able to see if the jet is open. One problem is that any debris is going to be on the hidden side of the jet so flush both the jet and the cross drilled hole with carburator cleaner and then use compressed air to thoroughly clean the jet of all debris. You should see the nice round hole of the main jet when it is clear.

Also make sure that the pathway to the priming bulb is not broken or leaking. If air can get into that circuit it will lean the fuel flow to the main nozzle.