My ride-on when it gets an increased load starts to surge ( revs increasing and decreasing) but when the load is removed continues to surge. The governor arm is moving so I expect that is what is the problem but I cannot find a reason. Can anyone offer advice?
Yes most likely but will cleaning it fix the problem, sometimes it will sometimes it won't and without knowing the carby type they can also suffer from wear around the butterfly spindle
I'd check the easy things first ,like make sure the air filter is clean and when the motor surges you can put the choke on a little to see if that fixes the problem if it does you must have a carby running lean problem.
Check the fuel is good and not old , check the fuel flow meaning the fuel filter is not blocked and the fuel tank breather is working.
You could remove the fuel bowl on the carby to check that the old fuel hasn't waxed up the insides of the carby.
It wouldn't hurt to replace the spark plug and check /adjust the spark plug gap.
I took the carby off and cleaned it with spray. The fuel is new. The solenoid piston seems sloppy as there is sideways movement in it. The engine runs for about 60 seconds while surging then stops. Leave it for 30 seconds then will start again and do the same thing. Thank you for your advice so far.
It could easily have a faulty fuel solenoid on the carby GWA.
What happens when a fuel solenoid fails? Trouble cold-starting, the engine suddenly shuts off, erratic idling, and hesitant acceleration are all tell-tale symptoms of a bad mower fuel solenoid in action. The solenoid's sole function is to either stop or allow gas flow, and defective units fail to carry out this task.
Take the solenoid out and put an earth jump lead to the solenoid body and other end to negative of the battery then put a lead from positive of the battery to the wire connector on the solenoid to make sure it's operating without sticking ,if it's sticking you could clean and lubricate the plunger shaft but sounds like it's loose by your description..If the solenoid is more like the one in the image below the earth lead will go to the lead with the earth type washer part.
Possibly wire the solenoid straight to the battery and that should tell you if it's a wiring issue if the problem doesn't happen when wired straight to the battery.
You may be able to start the mower with the solenoid removed and your finger blocking the hole so fuel doesn't leak out onto the motor and see if the motor runs without the problems.
The mower is about 6 years old. It had the issue once before but revtified itself. This time it has come back with a vengeance. Cleaning the carby out onky made it worse. I will try out the solenoid test tomorrow. I am leaning towards that as usually when they put an electronic device on a normally reliable machine it is a cause for issues.
On a 6 year old mower I wouldn't expect the body to be overly worn but as you say the problem is worse now proves the problem is the carby. Might be an idea to look around for a new one,
I found out that the mower is only 4 years old. I asked a local mower repairer to find a carby for me but after a comprehensive search they came back to me and said there is not one in Australia. I found one on amazon in the USA. I do not believe anything on a mower is rocket science so I stripped the carby down as much as possible and cleaned it with carby spray in every orifice I could find. Put it back together and now it is running fine. So now if all go well, in a couple of weeks there will be at least one spare 4X90HU carby in Australia. Thank you for everyone's advice.
