Now here's a question.....Kymco 4x4 Mule

[moizeau]

Looking for some knowledge. I know diddy squat about fuel injected petrol engines, give me a carb any day.
A mate has a Kymco 700cc fuel injected buggy. It started off being hard to start then once started wouldn't hit peak revs, now it won't start.
I've done all the normal stuff that I would do on one my bikes, mowers etc. to no avail.

It has fuel at the plug. I've removed the injector and it mists.
It has a spark.
I've confirmed valve clearances, fine now. The inlet was tight so reset it.
I have access to the factory manual so have even checked the various sensors (ohms), TPS, Air idle, temp etc. fine.
I've gone through as many connections as I can see and cleaned them all.
It has good compression.
The exhaust is clear.

When you first turn the key it tries, for a split second, to start, doesn't, then just turns over.
If you hit the starter multiple times for a second it tries to start multiple times, doesn't, then spits back into the airbox.

There is in-built diagnostics or sorts that should throw a fault but there isn't one.
The local dealer is crap and just a seller.

I can only think ignition or valve timing now. I can't see how the ignition timing could be out or the cam timing but I'm thinking the next step is rocker cover off, confirm the cam positioning at tdc. I have no idea how to do an ignition timing check on this. Easy with old points....a bulb.

Any ideas before I pull the valve cover off would be great.
Cheers

[bobins]

Does it have a cam or crank sensor, or are these some of the sensors you've checked ? The other thing might be a chewed woodruff key that's allowed the timing to wander.

Completely unrelated to your problem, but my mate had a 2 cylinder Briggs engine on a nearly new ride-on and it struggled to start. It turned out to be the camshaft that was made of finest Chineseum cheese - in fact the whole engine was a Chinese manufactured Briggs one

[moizeau]

It does have a cranks sensor, the one I haven't tested of course. Should be straight forward to check if the flywheel has moved by using the TDC mark and a straw down the spark lug hole.
Good call
Cheers

The bloody thing has only done 3500 kms!

[moizeau]

Well, I did mention the dealer was crap. He had it a couple of years ago because of a non-start when hot, took months to sort while he threw various parts at it including Coil, starter motor. Never got billed thankfully. It did come back fixed but when asked 12 months later what he'd done he 'couldn't remember' which either means it was something embarrassing, he really can't remember or his dad fixed it. It's family business run by a very good friend's potential son in law. Needless to say the unwritten law is not to talk about it.

Anyway, this is relevant because I've found the issue.
I checked the crank sensor and it passed, as expected because it did spark. I then put a screwdriver down the plug hole and started turning the engine over. The screwdriver slipped from being in line with the piston and jammed against the plug hole at an angle locking the piston. No problem, I'll back the engine off. 1/8th of a turn and the screwdriver is still jammed, odd. Another 1/8th while looking at the flywheel through the window, the flywheel didn't move and the flywheel nut/bolt (unsure at the moment) is unscrewing! It's bloody loose, well not torqued up at least. It must have sheared the key which has thrown the ignition timing out. Oil also dribbled out when I removed the centre flywheel cover cap which means it is 1/2 full of oil. No mention of this in the manual from what I've seen so it will be interesting to see what that condition is once the cover is removed.

I'm sure I remember him changing the flywheel and starter after he'd badly fitted a starter that then chewed it's teeth.

I couldn't understand how the ignition timing could have changed initially....unless of course a muppet has been in there and not torqued the flywheel up.

Thanks Bobins for the prod in the right direction.
Do you know that 'bobine' in French means 'ignition coil', well you were a good spark here, cheers.

[moizeau]

Yep, loose flywheel caused this

Cleaned the high spots up with a sanding wheel dremel attachment and reshaped a lawnmower woodruff key to fit. Luckily the crank isn't too bad and it still has enough meat in the groove of the flywheel to accept the key snugly. I'm going to lap the flywheel onto the crank to ensure a good fit and no unseen high spots.
I'll see tomorrow if it works.......