Bizarre engine behavior (Any ideas?)

2011 Yamaha WRX, location Nicaragua

Short story: Got 2 years of riding with no battery charging out of it and then since October 2015, it's been the most painful bike of all time, I want to stick an icepick in my temple and I'm completely baffled with what's going on.

The Problem: Video here: my wr250x At first, anyone would say it's "misfiring". It starts and dies, idles for a few then dies, it may a have a good run of 15 seconds of idle before it dies. With just a bit of throttle, it can't maintain a steady rpm either. One can see the rpms dropping out constantly in the video. But when it misses, the rpm indicator in CO mode drops to zero and it's like the whole bike voltage drops in and out, head lamp dims too. Almost like a bad lean angle sensor, which i experienced first hand in my racing days. But I checked the lean angle sensor, probed it, use dthe self-diagnostic...it's good.

Normally if the spark is missing, it just doesn't fire right? the rpms should still indicate and it would run a bit rough. So, I'm wondering the issue is in the wiring harness and/or circuits of the main switch, on/off switch, battery, fuse box...because those lines feed the entire system.

If I try to test ride, it's worse. sporadic and constant ON/OFF...keep the rpms up a bit and it limps along like a three legged dog. Maybe the head gasket blew again? I just replaced it a month ago, maybe I screwed up? I can't see how, I tried riding it two days and kinda felt like it did when I first blew the head gasket. And when that happened, I was in denial for a long time hoping it was just a leaking waterpump seal.

1) Crankshaft position sensor could maybe cause it? Installed new stator, flywheel and CPS last week, wiring is good, checked continuity everywhere.

2) If the timing chain was off by a gear tooth (I may have made a mistake!), would it cause this kind of behavior?

3) insight or ideas from the forum?

Wr250X Background: Bought here in Nica used, all work done by myself since, this is the chronological order of the work I've performed: new spark plug, new rear shock (revalved), new battery, new stator(June 2016, new stator(2nd one, Oct 2016), new battery, new spark plug, new fuel pump(actual pump swapped from plastic assembly), new fuel injector, new temperature sensor, new head gasket, new stator, new flywheel, all new relays (every single one), new coil, new pressure sensor, valve gaps within spec.,

I've electrically checked continuity on the ignition system and EFI and checked every connector terminal, switches, gone through every sensor in diagnostic mode, I've probed the sensor themselves like the manual instructs(lean angle sensor, speed sensor, throttle position sensor), the list is very long now...too much to post. *I've even swapped the ECU and the damn thing still won't run right with the problem I described above. I think i'm going to pull the camshaft cover off and check the timing sprocket marks at TDC, chain slack...I may have screwed up and not even know it.

Has anyone experienced or seen this kind of thing before?

Thanks!

Maybe the head gasket blew again?
What was the cause of that failure the first time?

it's an interesting reason...I laid it down dirt/gravel probably about 10mph, was messing around and it was dry and loose.

The symptoms started showing about a couple weeks after that. And i thought it was my fuel pump or something...dark rabbit hole.

Anyways, when I went to put the the head on, it has a 12mm bolt right into the frame...it was out of alignment. I had to loosen the bottom engine mount bolts, lift the motor, align them perfectly, then cinch'm down. It was off by a good 3/16". I had been riding it for a couple weeks with the frame pulling the head up...i'm sure my little spill jostled it and then it was pulling the head away from the cylinder.

That's my theory!

The fact that the tach from the computer drops to zero, it makes me think it's electrical, if it were mechanical, like the valves or head gasket, the computer wouldn't know the difference. For whatever reason, it thinks that it has died when it miss fires.

I've been wrong before though. Could be again.

You checked every ground, a wire could be loose and making good contact till the bike starts vibrating. So it'll check good at the connector with a meter, till the bike starts running.

My logic agrees and that's why I bought a used wire harness from eBay. I've checked everything, i really don't know what else to do other than swap out the wiring harness.

The main switch(key), on/off switch and statir/regulator all connect to the fuse box and feed power to th harness. I clean and checked them multiple times...haven't discovered it yet. I bought a wire harness off of eBay that's in good shape and had it shipped here last month. I'm thinking of swapping it out... seems like the last thing to do. Did you all watch the video?

Intrinsic wrote:

My logic agrees and that's why I bought a used wire harness from eBay.  I've checked everything, i really don't know what else to do other than swap out the wiring harness.

The main switch(key), on/off switch and statir/regulator all connect to the fuse box and feed power to th harness.  I clean and checked them multiple times...haven't discovered it yet.  I bought a wire harness off of eBay that's in good shape and had it shipped here last month.  I'm thinking of swapping it out... seems like the last thing to do.  Did you all watch the video?

Have you had the valve cover off?  I'm just going from the youtube video of course but your motor does not sound healthy.  If you've done any motor work I'd check that the cam chain is properly tensioned and the timing marks are aligned.

-morgan

I have to agree with the above....based on that video that seems like a motor issue......something is not right.  Pull the valve cover and check your cam timing, do a compression check etc.  Your engine sounds broken to me.....

Okay, I'll pull the valve cover, check the timing Marks and check the cam chain tension. I may have missed something. I'll post a pic too. It's good to know, because it's always kind of sounded like that.

\I can reposition the intake cam one tooth the other direction and give it a shot? what do you think? BTW, thanks for the suggestions guys!

Intrinsic wrote:

\I can reposition the intake cam one tooth the other direction and give it a shot?  what do you think? BTW, thanks for the suggestions guys!

Just so I'm sure I understand you, take your finger out of there and properly tension the cam chain, are your alignment marks off?  I imagine they will be.

I haven't done this on a WR but on a CBR600 there is enough play in the cam chain with the tensioner out to work the chain a tooth at a time back into position.  It's a pain to do it but doable and less drama than pulling cams.

Also: change your oil once you're up and running, my CBR had little flecks of metal floating around from the cam being off a tooth.

-morgan

My finger is just holding the gasket and cover up for the pic. The cam chain is tight in the photo; I did not remove the cam chain tensioner. I hate the cam chain tensioner on this motor, such a pain to reset...you have to rotate the crank counter clockwise for it to release without the chain skipping teeth. Maybe that's what happened? I'll for sure change the oil.

Intrinsic wrote:

My finger is just holding the gasket and cover up for the pic.  The cam chain is tight in the photo; I did not remove the cam chain tensioner.  I hate the cam chain tensioner on this motor, such a pain to reset...you have to rotate the crank counter clockwise for it to release without the chain skipping teeth.  Maybe that's what happened? I'll for sure change the oil.

Ah, I see. You should wait for someone more versed in the WR motor to confirm whether that's enough out of alignment to qualify for being off a tooth. I would check that your tensioner is working correctly or consider a manual tensioner--a Krieger worked well for me when my manual tensioner started failing.

-morgan

I adjusted the intake cam one tooth the other direction and problem didn't go away.

For the short amount of time it does idle (3-5 seconds), its idling for a shorter period of time and feels a little rougher.

So, I'm swapping the entire wire harness.

See if the problem goes away.  If it does, then I'll pull the cams and re-install, gap and finally it's solved.

If the problem is still there with the new wiring harness? Then I'm selling it or parting it out.

Intrinsic wrote:

I adjusted the intake cam one tooth the other direction and problem didn't go away.

For the short amount of time it does idle (3-5 seconds), its idling for a shorter period of time and feels a little rougher.

So, I'm swapping the entire wire harness.

See if the problem goes away.  If it does, then I'll pull the cams and re-install, gap and finally it's solved.

If the problem is still there with the new wiring harness? Then I'm selling it or parting it out.
 

Do you have a decent mechanic in your area that could look at the bike? Replacing the wiring harness is an awful lot of work for what just might be one bad connection or not a bad connection at all.

-morgan

I live in Nicaragua man, can't get parts unless I personally import them on a flight and moto mechanics are serious hacks. Seriously, if you seen what I've seen, it would make you cry and impressed all at the same time.

It's okay, I'm a ME of 20 years, I raced 10 years, AMA 600 Supersport for 5, I did most of my own engine work...Once I had an electrical gremlin and had to replace the wire harness, and it fixed the issue. Same with lean angle sensor and the list goes on.

Also, the conditions here are brutal. Electrical problems are common due to corrosion, humidity, rainy season...it's gnarly. My truck for example has had endless gremlins from corroded relays, connectors, etc. That's why I replaced all the relays on the the bikes wiring harness and damn there every sensor to eliminate potential culprits that I couldn't open up to inspect/clean. Same goes for the connectors. They've all been inspected/cleaned. I've crossed I think everything off the list except for the key switch and like you said a potential undiscovered short/open on the main power circuits.

One thing that's interesting, the main switch (key) could cause this problem/symptoms (based on circuit diagram) if it is faulty and it's the only switch I haven't been able to get inside and investigate. I'll see if I can hard wire the connector on the wire harness and test, before swapping wire harness. That would eliminate the key switch as a culprit at least.

One thing I can think of.....first, put the cam back to where it was...it was probably correct.  Second, I think I can recall people saying there is a connector buried behind the radiator/fan that on some bikes was not fully seated.  After a while the connection would cause all kinds of problems running wise.  Plugging it all the way in until it clicks fixed the issue. Might be worth a check.....

I swapped the "main" wire harness, went through every connector, started it up...

...and the problem is still there. Cuts out just like in the video I posted.

Though I already replaced the fuel pump(not the assembly), maybe I should open it back up, make sure everything is proper, never know.

Other than that, I've done everything one can do. Every sensor, switch, coil, injector, pump, wire harness, etc. has been swapped or verified good according to the manual.

Which means I basically have a new bike that still won't run. Also, verified the head gasket is not leaking. Oil is pristine.

Maybe I should pull the head again, remove the valves, etc...might discover something?

It really does seem like a fuel pump issue to me. Especially if the one you have fitted is a cheap ebay item.
I tried the replacement element thing in one of my pumps. It lasted a very short time in hot weather. Replaced it with a genuine item, and never looked back. Cost is the only thing, but probably very little compared with money already spent.

I can't see connectors or wiring being your problem. Whereas I have experienced more or less the same symptoms as you are, and it has been a stuffed fuel pump.

Not all pumps fail in the same way imo. I've had one fail instantly and completely. And one fail so slowly that detonation was the only symptom for a couple of thousand km (bit slow to wake up to what was going on there). That one eventually failed when the fuel got hot, but would work when it cooled off, as did another genuine one (early -00 part number. They're up to -11 now!). I'm on my fourth pump now, but the previous one, which failed instantly, lasted 1000hrs and about 20,000 km.

End of history. Apologies for dribbling on.

I bought a brand new fuel pump off of amazon and installed it into my existing plastic housing. $60 vs $380 for the whole assembly. Entirely possible connections are loose. I can't Buy a new fuel pump assembly until my next trip to the states... but I'll pull mine out again and see if there is something to deal with. Ivan also out my old one back in and see if te problem changes? If I could buy one today, I would and install Ian's call it done.

Regardless of what the problem is, I hope you get it fixed - then you can relax. Bloody annoying, but you've certainly given the issue a great deal of thought and work. Full credit!

THanks for the ideas, suggestions , support Yeah, it's been a rough deal here, this is my main mode of transpo living in the jungle with no alternatives. until I can get a new fuel pump assembly and try that. I need a moto to get around, it's been 5 minths!, so I'm gonna have to buy a new moto as soon as I am able to save some money.

So, I finally figured it out...While I finally decided to realign the camshafts I discovered the problem.

The crankshaft bearing/crankshaft has quite a bit of play in it.  I know, "Oh no....".

The tension from the camshaft chain tensioner masked the issue because it pulls the crankshaft up and removes the play.  When the tensioner is removed, the crankshaft has quite a bit of play in it.  

So what was happening was...as the generator flywheel rotates, the crankshaft position sensor is sensing from the rectangular bosses on the flywheel the timing and the rpms. If there is play like this (it's substantial), then there would be space between the sensor and the flywheel bosses, which means the sensor wouldn't pick up the signal to fire as well as resetting the rpm count. That's why the rpms where dropping to zero randomly and  the motor would die.

Splitting the cases and fixing this is a now a big project requiring special tools and a lot of parts/gaskets/o-rings that I just can't buy here in Nicaragua.  And as we all know, when doing this kind of thing, one is always going to come up on some part or tool, that one doesn't have...and for me,  that means I'm going to have a heck of time reaching the end, as I'll constantly be in need of something and unable to get it.

I'd buy a new motor if I could buy one here in Nicaragua, but that's never going to happen.  Probably just worth my effort to figure out a way to import one from the states rather than splitting the cases and embarking on a long long rebuild. Parting it out here isn't going to work either. Pushing it off a cliff makes sense too.

Obviously, that's very bad news mechanically and financially. So much for my fuel pump theory.

I do hope you get it sorted. It does seem to me that if it's one main bearing at fault, then it might be worth splitting the motor. In fact, whole aftermarket cranks aren't too expensive, really. All the very best with it.

Intrinsic wrote:

Probably just worth my effort to figure out a way to import one from the states rather than splitting the cases and embarking on a long long rebuild.  Parting it out here isn't going to work either. Pushing it off a cliff makes sense too.

I don't know how practical this would be from your location, but given you have crank damage, it may be worth sending your motor to Thumper Racing for a Big Bore kit and a Hot Rods Stroker crank. Displacement goes up to 306cc, and power is increased by about 50%. Riding impressions in this thread.