Chinese 16HP vertical shaft engine problems

[Dave M7040]

The idea of the fuel solenoid was to stop the engine from back firing when it is shut off. With time the top of the piston and cylinder head builds up with carbon and will get red hot like a glow plug in a diesel engine, when the key is shut off the piston continues to spin a few more turns and sucks in more gas /air mix and is ignited by the red hot carbon and fires when ever it wants and can break the connecting rod.So they put the fuel solenoid on it, probably more worried about warranty work then anything else cause that part is a ton of money. Idling the engine down and let it cool a bit before turning the key off works just as well.
Moving on to another thought, by chance is your fuel tank cap vent plugged up causing a vacuum in the tank? Is your gas tank under the seat ? or under the hood/ bonnet ?
Some engines have a black plastic spacer between the engine and carb and take a gasket on both sides of it. It is hard and brittle . This is where I drill my hole to tap threads for a hose barb to pick up the vacuum for my propane regulators safety device , I have used JB Weld to repair the ones I have broken.

Rocky I agree with your comments on the need for a fuel cut off solenoid but would like to suggest a second reason.

Cheap generators have no idle feature on them as an expensive Honda would that would idle the engine after it warms up and then kick it up to 3600 rpm when there is a call for power. This is done to reduce noise level and save fuel.

On the cheap generator, the carb does not have an idle circuit and when it runs it is at full speed. Getting the engine to stop from full throttle without a lot of run on and back firing is easily accomplished with the solenoid valve on the bottom of the float bowl.

I dont know if the garden tractor carbs with a solenoid are open or closed without power applied.

On generators, which do not have a battery, the solenoid only works while the generator is putting out power. A small amount of DC is taken from the generator to activate the solenoid which cuts off the fuel to the main jet and stop the engine.

Dave M7040

 

[Wazrus]

I'm with Soundguy. Sounds like a fuel supply problem. Did you clean out the fuel tank when you changed the carb? There may be a screen in the outlet of the tank that's clogged.

Thanks once again for all your replies. The fuel tank is - or was - under the bonnet. I 'lost' the bonnet years ago, as the new engine didn't quite fit, widthwise, but the hole centres were OK. Appearance hasn't been a priority. Your American engines all sound as though they have a fuel solenoid: the Australian version, or at least my engine, doesn't have a fuel solenoid at all and no, I didn't 'lose' it!
I checked the fuel cap and the tank venting and although there was some crap around the venting arrangement, it didn't seem to affect the problem. I tried running with the cap loosened also, to no effect. I note remarks about the hard plastic 'spacer' between the carb and the cylinder and the gaskets either side of it. I'll be looking at those, too.
Wazrus

 

[Wazrus]

Thanks once again for all your replies. The fuel tank is - or was - under the bonnet. I 'lost' the bonnet years ago, as the new engine didn't quite fit, widthwise, but the hole centres were OK. Appearance hasn't been a priority. Your American engines all sound as though they have a fuel solenoid: the Australian version, or at least my engine, doesn't have a fuel solenoid at all and no, I didn't 'lose' it!
I checked the fuel cap and the tank venting and although there was some crap around the venting arrangement, it didn't seem to affect the problem. I tried running with the cap loosened also, to no effect. I note remarks about the hard plastic 'spacer' between the carb and the cylinder and the gaskets either side of it. I'll be looking at those, too.
Wazrus

Wazrus here again: 8th December, 2016
Today, I stripped the fuel tank out and guess what? The very small strainer located inside the fuel delivery tube was full of crud! Did I hear you say 'no surprises there'? So the new carb, air cleaner, line filter and spark plug were all a bit unnecessary. I can, however, say with a deal of confidence that the engine will be good for at least another four or so years and I'll know where to look next time!
The machine did an hours' mowing without missing a beat yesterday morning. You beaut!
Thanks once again for your help.

Wazrus

 

[Rocky J]

Another mystery solved , I have had good luck with the Clone engines from china, I have noticed I have to be right on the adjustment of the exhaust valve for a easy spin start, if the adjustment gets a little loose it acts like a low battery, the compression release works well so it must be the electric starters are not over powered,I have looked inside of one of them and it was all metal ,dont see that much anymore .