I'm trying to repair this mower for a family member; this Hyundai is the first one I've worked on.

It would start, but it needed 20-30 pulls, and once you stopped it, the damn thing wouldn't start again unless you were lucky and could withstand another 30-40 pulls 

I removed the carburettor and gave it a good clean; it wasn't too bad. I changed the spark plug and tested the coil with a multimeter. I finally managed to start it, but it will not restart after running.

I reassembled it without the plastics and noticed a fuel leak from the tank. It is a Red Herring unless it introduces air into the fuel line; the crack is high on the tank.

I am thinking perhaps the ignition coil is breaking down under load.

I am going insane and would appreciate some advice. I have usually got a Hayter, Stihl or Honda running by now 

Thanks all,

Hi Changy, and welcome to TGMF.

It could be the coil, but I would check everything else thoroughly before throwing money at it.  Does your one have a choke, or do you have to prime it to start.

As I have no idea what engine is on yours, If it has a choke then make sure it's closing fully when cold and opening when hot.

See if it will start if you remove the air filter and spray a little carb cleaner or a drop of fuel direct into the intake. If it does then you still have a carb problem.

It's also possible it could be flooding slightly and taking a few pulls to clear the excess fuel when you try to start it.

Hi Mick,

Thanks for the reply. 

It's a strange fault. Once it is running it cuts well, but when I tried longer grass it died on me. I wonder if it's unable to get enough fuel which means your carburettor line is closer to the mark. I managed to start it by spraying carb cleaner into the inlet.

Yep it does sound like it's running a bit lean.  A good clean of the carburettor should cure this. Make sure tank cap is breathing, and make sure you have good flow from the tank as well. 

Also check gaskets on front and back of carb are fitted the right way around, if not this can also cause issues.

This is now driving me mad.

Despite the mower starting after several pulls, it misbehaves and doesn't feel like it is running correctly. It doesn't seem to rev fully, and as soon as you cut some longer grass, it dies. If you try to restart it, you get a backfire. It's also hot, and so I suspect the timing is wrong.

I took the flywheel cover off and rechecked it; the key looked strange, almost as if it was at an angle. I've attached a photo, but correcting the angle and lighting is hard.

Any suggestions are welcomed, and also a recommendation for a flywheel puller. You cannot tap this one from below because there is no access.

Grrrr.

I called my sister and asked about the mower. I now know she ran over a large stone which brought it shuddering to a halt. I used the old-school method to remove the flywheel; a hammer!

You can see the key has sheared the shaft 

Schoolboy error, I should have asked for more information 

Yep, that's taken a fair old knock, must have been a big stone.

Glad you found the fault, it should run nicely after you change that key. 

Quote from: Mick on May 23, 2023, 08:28:16 PMYep, that's taken a fair old knock; it must have been a big stone.

Glad you found the fault, it should run nicely after you change that key. 

Mick,

Could I clean out the shaft to ensure a better fit of the key? I have never seen one that looks like that. I am used to a straight key and shaft slot, so am I correct in thinking this one started life differently because of the taper?

TIA

Yes tap the remains of the key out with a tiny punch or an old screwdriver, it should come out ok.

The key is more of a woodruff type than a straight key, and is slightly half moon in shape with the curve fitting into the shaft. You will need to get the right key for the job.

Quote from: Mick on May 24, 2023, 07:56:02 PMYes tap the remains of the key out with a tiny punch or an old screwdriver, it should come out ok.

The key is more of a woodruff type than a straight key, and is slightly half moon in shape with the curve fitting into the shaft. You will need to get the right key for the job.

Thanks, Mick, I will get onto it later. Im in the middle of sorting some Stihl petrol strimmers and Kombi tools and time is tight.

I replaced the woodruff key; it was a PITA because it constantly moved. I used a gasket sealant to add adhesion, and the flywheel slotted home. You can see how the original key had sheared.   

It started after several pulls, but again, it took 4-5 pulls to restart.

Does anyone have information on the carburettor? I wonder if the setting of the main jet is incorrect.

Changy, have you got a pic of your carb you can share with us? just so we know what carb we're dealing with.

Here are some photos of the carburettor.
   

Thanks.  So it's a primer version, now they normally start very well so my next question will be is it priming?  Primer button, and the little hose must be in good condition, and because it relies on pressurising the bowl to push the fuel up the main jet the bowl seal must be sealing properly. You should be able to see fuel being push up into the venturi when you press the primer button.

Hi Mick

I checked the primer and rechecked all the usual suspects. The bowl seal is fine.

I may have found the problem, but it is weird. If you pull the starter and then pull it again quickly while it is still rotating, it starts.

I decided to tune the coil (brand new) by adjusting the air gap. It was fussy about the gap, and it is now much easier to start. It isn't perfect, but it's acceptable.