PCX 125 Died Mid Ride

[scootin]

Hey folks,

After a rear wheel puncture last week and (seemingly) successfully swapping out the wheel on my 2013 PCX to my 2016 PCX, disaster has struck again. Riding home today, 60mph, the PCX 125 lost power mid-ride and came to a gradual halt. Pushed the b*stard about 2 miles home!

Now, the bike starts up as usual but the throttle gives absolutely nothing and as soon as I let go of the brake / ignition, the bike cuts out. Going to swap out the spark plug but I've a feeling it's not going to be that easy. Battery seems fine and everything has power. Would appreciate any words of wisdom ~ not having a great time of it lately!

[iceman]

Seems its just the alternator (atart) working and no fuel/drive. Check the belt to see it's actually ok.

[scootin]

Seems its just the alternator (atart) working and no fuel/drive. Check the belt to see it's actually ok.

I'll take a lookie at the belt tomorrow, iceman - thanks once again for your advice and input! The belt giving out was my first thought, even as the PCX was losing power, but I've only put 9k miles on the bike... Then again, those 9k miles are from 5 days a week, 25 mile a day commuting for almost a year!

[iceman]

That amount of use is nothing really - pizza delivery bikes must clock up lots more in all weathers and are constantly stopping and starting the bikes.

Hmm, if the variator end of the CVT is driven from the engine, then I imagine with the bike on the centre stand and the engine ticking over using the start held it, if the belt is gone then I believe the rear tyre should not rotate at all < unless I have this wrong?

I did 19,000 or so miles on my first belt, changed it as it was 4,000 past the recommended limit and I had never inspected it before. Came out looking almost as good as the new one - same width, no cracks on either side of the ribbed belt - kept it as a spare but probably no use as I do not carry it and rubber ages over time.

Could be fuel, a connector come loose, loads of things. Do you see any flashing on the dash? Often there is supposed to be a flashign sequence if the ECM detects sensor issues or such.

[Coasting]

Sorry to hear!

I'm a bit confused by your description; is the engine actually firing when you try to start it - or is it only turning over on the "starter motor" and not firing?

Would be very surprised if the belt had anything to do with it - in my experience they're damn near indestructable (despite me going significantly over the recommended change interval).

[scootin]

That amount of use is nothing really - pizza delivery bikes must clock up lots more in all weathers and are constantly stopping and starting the bikes.

Could be fuel, a connector come loose, loads of things. Do you see any flashing on the dash? Often there is supposed to be a flashign sequence if the ECM detects sensor issues or such.

Good point on the mileage! I do "thrash" the bike, at least insofar as you can thrash a scooter - full throttle everywhere, dual carriageway and back roads, but still maybe a more durable machine than I've given it credit for.

No weird startup sequences or lights staying on.

Sorry to hear!

I'm a bit confused by your description; is the engine actually firing when you try to start it - or is it only turning over on the "starter motor" and not firing?

Would be very surprised if the belt had anything to do with it - in my experience they're damn near indestructable (despite me going significantly over the recommended change interval).

Hey Coasting, thanks for getting involved!

I can try to get a video tomorrow, but basically when you hold the brake and press the ignition to start the bike as usual, the engine starts up slightly half-heartedly. If I pull the throttle at this stage, absolutely nothing happens, the bike just continues to purr away as long as the ignition button is pressed in. As soon as I let go of the ignition button / brake, the bike cuts out.

[iceman]

Belts do break - several people on this forum have experienced that!

It seems all you are seeing is your turning over the alternator, no actual engine start (the alternator/starter is the same item).

You do have fuel? (silly thing but some people have run out whilst riding). Did you fill up a little before stopping?

[Coasting]

Belts do break - several people on this forum have experienced that!

I just did a little "Googling" and was surprised to find some examples happening here. It's quite odd; some seem to have failed very prematurely whereas mine have looked like they could do twice the recommened interval and still be in good condition.

It seems all you are seeing is your turning over the alternator, no actual engine start (the alternator/starter is the same item).

That's what I was trying to ascertain. If it were my bike I'd be removing the spark plug and earthing it via something like a jumper lead to see if I had a spark whilst cranking. If so then most likely a fuel problem (insufficient quantity, failed pump, blocked filter, contamination etc).

Probably begs the question of how much effort one wants to put into resolving it; sometimes it's just easier to get a dealer to diagnose it.

[DAB]

Is it firing our just turning on the starter motor? Is the exhaust getting warm?

[you you]

Plenty of fuel in it?

[scootin]

Morning all, not looking good I'm afraid - thought I'd take the opportunity to change the oil while the bike was out of action, was horrified to see a trickle of only ~100ml of oil come out. No idea what's happened there and where it all went, but I'm guessing the engine has siezed?

Prior to discovering there was pretty much no oil, I'd siphoned out the half tank of petrol just in case it was bad and added a fresh half a tank.

Checked the spark plug, it looked brand new, but still have another one on the way. Oil filter was also spotless. Waiting on some tools to get in and check the belt, but going to assume it'll be just fine.

Have stripped all the faring off the sides and back, cracked a couple of pieces in the process. Unsure of where to go from here. New engine?

[you you]

If the engine had seized it wouldn't turn over. Any bits in the oil?

[Coasting]

That's the rub with the PCX - it doesn't burn any oil when new (and we get complacent about checking it) - and then when consumption starts to increase it gets low or can run out before we realise. I make a point of checking mine every 2 or 3 days now - and HAVE to carry extra oil if I shoot off on a 100 mile days trip. It's done about 300 miles since my last change and is now coming up on needing an extra 100ml.

But having just said all that, if it's turning over on the "starter" then it's clearly not seized. Keep in mind too that it needs to be on the centre stand to get most of the oil out - AND you'll get a bit more if you tip the bike by a few degrees whilst it's on the stand (at which point it'll start running down the stand).

So best guess is that you've probably dodged a bullet by the skin of your teeth. I'd put the right amount of oil in to bring it up to the full mark and try to start it again. It probably won't make any difference given that they don't have a low oil pressure cutout (or at least they don't on my model), but it's something that needs to be put right before you can do anything else anyway - and there's a small chance that it'll get it going.

Other than that you just have to make a decision as to what you're prepared to try before you hand it over to a dealer. Fundamentally it's one of 3 things: fuel, ignition or "something else". If it's not something like a blocked air intake then the "something else" is probably going to mean something catastrophic - but that's probably unlikely. First thing I'd be wanting to test is if I was getting a spark - to do that I'd whip the plug out - put the HT lead back on - and earth it to the frame with a jumper lead - and then (keeping body parts well away) crank it over (preferably in a dark place) to see if there's a spark. If so then you're probably looking at a fuel issue - at which point I'd check the fuel pump and fuel filter.

Issues like this are frustrating - so I think it's important to just try to put that aside and do a "Mr Spock" logical progression.

[scootin]

Nothing to report in the trickle of oil that came out, you you!

Sorry, not very mechanically-minded so might have given an inaccurate explanation of what's happening when I start the bike. Push the brake in, push the starter button, bike splutters into life and usually conks out after a few seconds even with the starter button held in. Or, sometimes it'll splutter away for a bit longer and cut out as soon as I release the starter button. During the time it's spluttering, pulling the throttle does absolutely nothing. Was able to see the throttle cable now that the bikes stripped down and it looks to be intact and working as it should.

Coasting, definitely slacked on checking the oil, especially as it's a commuter.

At a loss but really appreciate you guys taking the time to help with the troubleshooting! Got Fri, Sat, Sun off so will use this time to put in fresh oil and investigating based on all of the advice here. Fuel intake, plug, spark etc. Going to try and check valve clearances while I'm in there and give it a basic servicing based on the manual.

[Coasting]

Unfortunately "not very mechanically minded" and ""check the valve clearances" are fairly mutually exclusive IMO. I am pretty mechanically minded and even I won't go near valve clearances with a barge pole.

So from what you're saying it does fire up ... but barely? That's sounding more like it's getting starved for fuel, but it could be many things. Personally I'd probably give it to the dealer and give them a time limit of a couple of hours to find something (ie not a blank cheque) given that they do that kind of stuff for a living and will probably be able to make better decisions than us amatuers due to their experience.

[gn2]

Has the air filter ever been changed?

[scootin]

Hey gn2, same part of the world as me!

Never changed the air filter and picked this scoot up with just 2k miles on the clock but checked today and it at least "looked" to be in good condition. I can't get it off at the pipe to check because the screw that holds the jubilee clip thing in place has no thread to latch onto, but the interior cover and filter part were fairly clean, if that's any indication.

I took a video of trying to start it, hopefully this sheds more light. If you guys are unable to view it, please let me know. Throttle might sound funny because the air filter is off.

https://drive.google.com/file/d/16KSO_V ... sp=sharing

[iceman]

Hard to tell on the PC at work (low audio) but do you hear the fuel pump fire up for a few seconds when you turn the ignition full way? It does seem to be starved of fuel or something like that.

[Coasting]

Never changed the air filter and picked this scoot up with just 2k miles on the clock but checked today and it at least "looked" to be in good condition. I can't get it off at the pipe to check because the screw that holds the jubilee clip thing in place has no thread to latch onto, but the interior cover and filter part were fairly clean, if that's any indication.

The element pops out of the housing, but the whole assy still runs the entire length of the housing. Not sure what you mean by "can't get it off at the pipe"? But regardless that's clearly not the problem since you have the same issue with the filter removed.

I took a video of trying to start it, hopefully this sheds more light. If you guys are unable to view it, please let me know. Throttle might sound funny because the air filter is off.

https://drive.google.com/file/d/16KSO_V ... sp=sharing

That was very helpful. Seems like a lot of cranking without firing - and then firing right at the end but dies again quickly. Personally I'd put my money on it being either a fuel supply problem (broken fuel pump) or the ECU doing something funny (ie not getting what it wants from a sensor). I'm almost wondering if there's a way you could try slightly pressurising the fuel tank to rule out a pump failure (with all the usual cautions regarding working with a flammable high-energy liquid and a tank not designed to be pressurised to any significant degree).

Was also interesting to see that it stops and then restarts cranking. Is it you or the bike doing that? Mine cranks continuously until it either starts or I release the switch (only time it doesn't start is if I've got the plug disconnected).

As an aside, I noticed that you seemed to be able to move that left hand brake lever in one hell of a big amount; I adjust mine so that it's the same as the right hand one for the front wheel (the adjustment is at the end of the brake cable at the back of the bike down real low -- you can easily adjust it by hand - real quick and easy to do).

[Inoplanetyanin]

If the engine stopps turning with the start button pressed, it would mean there is a strong mechanical resistance inside, likely a seized piston or broken rings, or something with the rod/valve. In either case, not good. Plug the spark plug hole with some newspaper and see if it shoots out, if you don't have a proper cylinder pressure gauge.