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 Need help diagnosing engine stuttering

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HalBran




PostSubject: Need help diagnosing engine stuttering   Tue Oct 14, 2014 8:47 am

Hi,

During yesterday's ride, I encountered engine stuttering and need your help to diagnose this issue. I've lost all confidence in the bike and I'm now afraid this bike won't bring me home Pray . I need help to diagnose the issue with certainty so I can restore my confidence. I can't bring the bike to a mechanic because I'm afraid they won't be to replicate the issue and thus not fix it.

The syptoms:
The bike was running perfectly and after riding easy on the road for 2.5h in beautiful sunny 15C (60 F) weather, the bike started stuttering (kind of like misfiring). This happened 5-6 times and lasted maybe 5 seconds each times. I upright, straight and was going around 50 mph. It was possibly happening when going uphill but it might just be a coincidence since the issue happened only a couple of times. The bike would also randomly die when stopping at stop signs. I had about 1/2 a tank full of gas.

The setup:

  • 2008 WR250X
  • Bike #110 produced in March 2008
  • 13 000 km (8000 miles)
  • Fuel pump replaced around 6000 km by previous owner
  • Fuel pump replaced by me 2 weeks ago with new for 2013 fuel pump (#3D7-13907-10)
  • AIS removed (by previous owner)
  • Power Commander V (by previous owner, map with stock exhaust and airbox mod)
  • K&N air filter (by previous owner, haven't cleaned it in a while)
  • EXUP present but disconnected (by previous owner)
  • Stock exhaust
  • Flapper door removed (by previous owner)


Recent issues:
3 weeks ago, without any notice or weird behavior before, the fuel pump stopped priming when I tried to start the bike during a 25C (75 F) ride. I verified fuses, connections, and the connection behind the radiator and handle bar that seems problematic, etc. without success. After letting it sit for 2 hours it started fine. My diagnosis was a dead fuel pump. I replaced it myself with the new for 2013 fuel pump part #3D7-13907-10. In the process I also replaced the spark plug. After installation I noticed the dealer had sold me a different spark plug (NGK CR9E single electrode) than what's recommended in the service manual and what was on the bike before (NGK CR9K double electrode). The new fuel pump has about 200 km on it and unfortunately I don't have the old fuel pump anymore.

My (mechanically challenged) diagnosis:
Since I never experienced mechanical issues before the fuel pump gave up 3 weeks ago, either I did not fix the issue by changing the fuel pump (350$ down the drain?) or the issue was fixed by changing the fuel pump but I created another issue in the process.
That's where I need you guys help!

Thanks in advance! thumb
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motokid
Moderator
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PostSubject: Re: Need help diagnosing engine stuttering   Tue Oct 14, 2014 10:03 am

You've hit most of the obvious stuff.

Some people have had weird experiences when battery terminal connections were loose. Check those.

Make sure your battery is fully charged and holds a good charge.

Fuel. Spark. Air.

A possible vacuum leak somewhere? scratch

Some people have had issues with cracked porcelain on spark plug.

Since you have a stock exhaust you could try disconnecting the PC-V.

How long have you owned bike? How much time riding it before these things started to happen?

Is it possible you've gotten bad gas?

Have these issues shown themselves through multiple tanks of gas?
Are you using premium octane gasoline from a gas station that see's lots of business?



_________________
2008 WR250X
Gearing: 13t - 48t
Power Commander 5 / PC-V
Airbox Door Removed - Flapper glued - AIS removed
FmF Q4
Bridgestone Battlax BT-003rs
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HalBran




PostSubject: Re: Need help diagnosing engine stuttering   Tue Oct 14, 2014 11:52 am

motokid wrote:
You've hit most of the obvious stuff.

Some people have had weird experiences when battery terminal connections were loose. Check those.

Make sure your battery is fully charged and holds a good charge.

Fuel. Spark. Air.

A possible vacuum leak somewhere? scratch

Some people have had issues with cracked porcelain on spark plug.

Since you have a stock exhaust you could try disconnecting the PC-V.

How long have you owned bike? How much time riding it before these things started to happen?

Is it possible you've gotten bad gas?

Have these issues shown themselves through multiple tanks of gas?
Are you using premium octane gasoline from a gas station that see's lots of business?  


  • Batterry, I will check this as I've obviously put a big strain on the battery when my fuel pump gave up.
  • Vacuum leak: Don't know where to search, any idea?
  • Cracked porcelain. I will check this soon. I was thinking that maybe the spark plug "cover" or whatever that's called might have moved and was doing a bad contact with the spark plug.
  • PC-V I can try this but I had no issues before with it connected.
  • I've owned the bike for 2 years, 6000 km. and no issues before.
  • Bad gas is always possible but I filled up in a station that sees a lot of usage so gas was "probably" fresh.
  • This issue was seen through only one tank at the moment. I filled-up half-way through my ride and the issue happened only at the end of the ride. I made a b-line for home when it happened to avoid being stranded.
  • I'm using regular gas all the time and have been doing so for the last 2 years without issues.


I might add that I can be mechanically challenged at times so it's entirely possible I've messed something up/made errors when changing the fuel pump/spark plug. I thought at first maybe pinched fuel line (Would have had the issue throughout my ride no?) or problem with Spark plug installation (I know I was mightily scared of stripping the head when installing the spark plug, possible problem there?)
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blusmoke




PostSubject: Re: Need help diagnosing engine stuttering   Tue Oct 14, 2014 2:10 pm

Sorry this happened to you out on a ride bud.
I would retrace your steps so to speak going over everything you've done recently and make sure nothing has been left off, pinched, come undone...I would first check that the fuel line is not kinked it can and will give you a symptom like this.
Next i would make sure the power commander and wiring are in good shape since most of those connections are right by the spark plug.
Definitely inspect your plug, make sure it isn't compromised.
As for checking for vacuum leaks have the bike idle and spray a little starter fluid(or carb cleaner) on the joints and connections of your throttle body/intake manifold your idle will either lower or raise though you probably don't have any unless you've removed any vacuum lines.
Then get some premium in her and ride around see if you can make it happen again.
good luck, I hope it is something simply
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HalBran




PostSubject: Re: Need help diagnosing engine stuttering   Sun Oct 19, 2014 9:12 pm

Thanks everyone for your help diagnosing this issue.

While checking various components and re-tracing my last maintenance (fuel pump and spark plug) I noticed the ignition coil was fairly rusty and didn't look too good (I even noticed a rust mark coming out of the hole on the side of the engine to blow off dust near the spark plug):



Is that rust normal? Do you believe this could affect the spark?

Nevertheless I replaced the spark plug with the recommended one, torque it to spec, used dielectric grease to help the connection as recommended and cleaned the ignition coil a bit. I also noticed the ignition coil was not seated all the way and was fairly though to get out (I was barely able to pull it out by hand)

I also made sure the fuel line was not kinked and that connections were tight.

After a 30 min ride, the engine died twice at stop signs.

Here's my theory: The ignition coil was rusted/fused to the old spark plug. When replacing the spark plug, the contact was not optimal due to the rust and might have caused ignition issue. This would explaing why this situation started happening after my fuel/pump and spark plug change.

So should I replace it? Anyone have any idea of the costs of those? The manual says it's part: Mitsubishi F6T558 but I have a hard time finding those in Yamaha's parts.
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rsteiger

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PostSubject: Re: Need help diagnosing engine stuttering   Sun Oct 19, 2014 9:22 pm

https://www.rockymountainatvmc.com/oem-schematic/2

It is listed on Rocky Mountain ATV site as Item 7 (8ES-82310-00-00 IGNITION COIL ASSY - $88.87) on the Electrical 1 Parts diagram for a WR250R.
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HalBran




PostSubject: Re: Need help diagnosing engine stuttering   Mon Oct 20, 2014 12:57 pm

rsteiger wrote:
https://www.rockymountainatvmc.com/oem-schematic/2

It is listed on Rocky Mountain ATV site as Item 7 (8ES-82310-00-00 IGNITION COIL ASSY - $88.87) on the Electrical 1 Parts diagram for a WR250R.

So you think my coil look bad enough that it could cause those issues and I should go ahead and replace it?
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morgan9283




PostSubject: Re: Need help diagnosing engine stuttering   Mon Oct 20, 2014 1:27 pm

HalBran wrote:
rsteiger wrote:
https://www.rockymountainatvmc.com/oem-schematic/2

It is listed on Rocky Mountain ATV site as Item 7 (8ES-82310-00-00 IGNITION COIL ASSY - $88.87) on the Electrical 1 Parts diagram for a WR250R.

So you think my coil look bad enough that it could cause those issues and I should go ahead and replace it?

Does anyone know if the WRR has an in-line fuel filter?  I'd check that if so.  But you might also want to pull the tank, dump the gas and look for debris in the tank.  I'd get fresh gas from a different station just be sure.

Vacuum leaks are a nightmare to troubleshoot but in my admittedly limited experience this does not sound like a vacuum leak.

When the bike dies have you tried opening the fuel tank immediately to see if you get a sucking sound?  Intermittent stalling can be a blockage in the tank vent.  I've not heard this happening with the WRR/X but I can't imagine it's immune.

Once you rule out blockage in the fuel lines/tank, replaced the fuel and checked that the vent is venting I think replacing the coil would be a reasonable next step.  Where are you located?  It would be nice if you could locate a loaner coil so as to not spent $90 just to troubleshoot.

-morgan
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HalBran




PostSubject: Re: Need help diagnosing engine stuttering   Mon Oct 20, 2014 2:48 pm

morgan9283 wrote:
HalBran wrote:
rsteiger wrote:
https://www.rockymountainatvmc.com/oem-schematic/2

It is listed on Rocky Mountain ATV site as Item 7 (8ES-82310-00-00 IGNITION COIL ASSY - $88.87) on the Electrical 1 Parts diagram for a WR250R.

So you think my coil look bad enough that it could cause those issues and I should go ahead and replace it?

Does anyone know if the WRR has an in-line fuel filter?  I'd check that if so.  But you might also want to pull the tank, dump the gas and look for debris in the tank.  I'd get fresh gas from a different station just be sure.

Vacuum leaks are a nightmare to troubleshoot but in my admittedly limited experience this does not sound like a vacuum leak.

When the bike dies have you tried opening the fuel tank immediately to see if you get a sucking sound?  Intermittent stalling can be a blockage in the tank vent.  I've not heard this happening with the WRR/X but I can't imagine it's immune.

Once you rule out blockage in the fuel lines/tank, replaced the fuel and checked that the vent is venting I think replacing the coil would be a reasonable next step.  Where are you located?  It would be nice if you could locate a loaner coil so as to not spent $90 just to troubleshoot.

-morgan

When I replaced the fuel pump there seemed to be a filter right on the pump itself so I would guess there is no other filter. I will need to verify in the manual.

I got fresh premium gas and the bike died right after fill up. The tank was only half-empty when I filled up. Don't know if it could be related or just a concidence. I will try to open the gas cap to see if there's a sucking sound.
I'm in Canada might be though to locate a loaner coil. From the picture I saw from new coils they definitively looked better than mine. Mine seems to have expanded with rust. I called my dealer and it's 110$ CAN. GAHHHH
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morgan9283




PostSubject: Re: Need help diagnosing engine stuttering   Mon Oct 20, 2014 2:53 pm

HalBran wrote:
morgan9283 wrote:
HalBran wrote:
rsteiger wrote:
https://www.rockymountainatvmc.com/oem-schematic/2

It is listed on Rocky Mountain ATV site as Item 7 (8ES-82310-00-00 IGNITION COIL ASSY - $88.87) on the Electrical 1 Parts diagram for a WR250R.

So you think my coil look bad enough that it could cause those issues and I should go ahead and replace it?

Does anyone know if the WRR has an in-line fuel filter?  I'd check that if so.  But you might also want to pull the tank, dump the gas and look for debris in the tank.  I'd get fresh gas from a different station just be sure.

Vacuum leaks are a nightmare to troubleshoot but in my admittedly limited experience this does not sound like a vacuum leak.

When the bike dies have you tried opening the fuel tank immediately to see if you get a sucking sound?  Intermittent stalling can be a blockage in the tank vent.  I've not heard this happening with the WRR/X but I can't imagine it's immune.

Once you rule out blockage in the fuel lines/tank, replaced the fuel and checked that the vent is venting I think replacing the coil would be a reasonable next step.  Where are you located?  It would be nice if you could locate a loaner coil so as to not spent $90 just to troubleshoot.

-morgan

When I replaced the fuel pump there seemed to be a filter right on the pump itself so I would guess there is no other filter. I will need to verify in the manual.

I got fresh premium gas and the bike died right after fill up. The tank was only half-empty when I filled up. Don't know if it could be related or just a concidence. I will try to open the gas cap to see if there's a sucking sound.
I'm in Canada might be though to locate a loaner coil. From the picture I saw from new coils they definitively looked better than mine. Mine seems to have expanded with rust. I called my dealer and it's 110$ CAN. GAHHHH


You may want to check that fuel filter on the pump itself to make sure it's not clogged.

If the problem occurred with multiple tanks of gas gas is probably not the problem. I would try to rule out crud in the tank.

In case the subtlety was missed: you need to open your fuel cap immediately after it dies to see if it's a suction issue. The tank will slowly pull in air over time and the vacuum will be lost if you don't check immediately.

Let us know what you find.

-morgan
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blusmoke




PostSubject: Re: Need help diagnosing engine stuttering   Sat Oct 25, 2014 4:19 pm

IMO the coil is your problem...
I would start looking for a replacement immediately.
It shouldn't look like that and has got to be arcing and shorting its self out. FYI when I changed my spark plug, mine was slathered in a healthy amount of grease apparently to prevent this very situation.

That "filter" on your pump is there more to wick up the fuel when the level is low and sloshing about, its more of a screen and isn't designed to trap dirt.

heres a used ebay coil for a decent price only $30
http://www.ebay.com/itm/08-WR250X-WR250R-ignition-coil-spark-3-/190546065995?pt=Motorcycles_Parts_Accessories&hash=item2c5d6e3a4b&vxp=mtr
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BackRoader

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PostSubject: Re: Need help diagnosing engine stuttering   Sun Oct 26, 2014 10:47 am

Pretty well the same symptoms here as my recently aquired 2009 is randomly shutting done.
I have done all the checks as mentioned on this thread and have gone as far as pulling connectors appart and cleaning them.

I will test ride today with a new plug, new fuel again (a little Sea Foam again) and see if it was the fix.

A new programmer and FMF Pipe are sitting on bench, ready for installing. I figure I need to get the bike running well before adding anymore complications to the current situation.

Update; did a 30 minute run tonite and no issues.
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66T

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PostSubject: Re: Need help diagnosing engine stuttering   Sat Nov 01, 2014 10:41 pm

Sorry to read that your bike is being a worry.

Mine was running (and starting) a bit off from about 3,000km and cutting out randomly from about 7,000km, to final expiry at just over 8k. It turned out that it was the charging side of the stator. Symptoms can vary according to the type of damage to the charge windings, though.

Simple to check: just measure the charge rate at idle across the battery terminals. It should be very close to 14v DC, and not vary when you rev it up. Australian stators have the same part numbers as yours, so I assume this info is good for US bikes.

There were no new stators in Australia, but the ones from America are bargain priced from MR Cycles (by our standards: about US$110.00, I think). Ours are AU$377.00, according to one dealer here, so I bought a spare one.

I may be way off with what's wrong with your bike, but it's so easy to check.

All the best and keep us informed?
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HalBran




PostSubject: Re: Need help diagnosing engine stuttering   Mon Nov 03, 2014 9:55 am

Here's a quick update and again thanks for your help!thumb

This weekend, I charged the battery and replaced the coil, cleaned and re-installed everything as you guys suggested (being careful to avoid di-electric grease on the coil and spark plug contacts). I let the bike idle for 40 mins without dying. I made sure it went through the temperature range, it got hot (the fan was running).

I also verified the charge rate at it was at 14.25V at idle and momentarily dipping to 14.22V on throttle so I guess the stator is fine.

Then I went for a 2h ride in near freezing temps. Did not experience any stuttering, stalling or power issues. I am cautiously optimistic that my issue is now fixed. wings

Unfortunately I've stretched the season as far as I could, snow is expected this week so I will to resumed testing next spring, hoping my issue is fixed for good! GAHHHH
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66T

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PostSubject: Re: Need help diagnosing engine stuttering   Tue Nov 04, 2014 2:22 am

Glad you got it sorted. Charging woes are a pita, so a good thing all is well there thumb
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