Weird symptoms. Need your expertise please...

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Now I'm not sure if gas can get to the charcoal canister either, after reading the FSM a few times. There are some very detailed diagrams of the canister and routing. For the California bike, there are 2 hoses running from the tank: 1 runs directly to outside atmosphere (to the ground) to release overfill gasoline and 1 runs from the top of the filler to the canister to capture fume. Normally the canister ever sees is fume and this fume gets recycled back to the engine by the hose that goes back to cyl#3 and #4.

For the non-CA bike, the 2 hoses from the tank just run directly to under the bike and released directly to atmosphere.

 
I wish you would have tried the "fill it only 1/2 way and see if the symptoms repeats itself" test before cutting anything.  If you don't try just one thing at a time, you may not (likely won't) know what ultimately fixes it.  The 1/2 fill test will help much more definitively identify the source of the problem in the fuel venting system, in your case, to include the canister and its plumbing.  Since you have cut one of the lines, maybe go with a full fill up next tank in an attempt to keep things at "one fix at a time"?

 
One of the hoses coming off the tank drains the space between the cap and the filler neck. It has nothing to do with the evap system. 

 
Just filled up this morning, as usual, after 250 miles and filled with 5.8 gal. No improvement. Still die at idle after riding for 25 miles to work. I should use a different gas station. Stupid me. I used the same gas station as before.

More observations:

- When riding on the freeway at ~70 mph, holding the clutch and return the throttle to idle, I saw the engine rpm slowly dropped back to the lowest mark (probably around 500 rpms) and the engine died while cruising. However, everything else on the dash still worked as usual even after the engine died: speed/coolant temp/outside temp etc... still displayed properly and no check engine light.  I'm pretty sure this rules out electrical problem?

- Release the clutch restarted it. Then when clutched or stopped,  I had to open and hold the throttle to keep it above 1000 rpms so the engine doesn't die. After arriving at work after 25 miles, it still died when I closed the throttle. After a few restart/die/restart in the parking, the throttle is back to normal at around 1100rpm and did not die.

- Does this sound like TPS problem? I'll run the diag tonight. I didn't not see check engine light turned on? Would TPS problem trigger the check engine light?

- It also ruled out charcoal canister problem too, yes (as the canister isn't in the loop)?

Things to try next:

- I always filled up after riding 250 miles since new and never had any problem until now. May be I ran it too low? But that was how I filled it for the last 40k miles. I'll fill up at 200 miles next time. I also never overfilled. I stopped when the gasoline reached the bottom of the filler neck. Again, always that way for the last 40k miles.

Thank you all!
mike-

 
Ok, just went out to my bike and just checked and verified the following:

- it started immediately and idled perfectly

- put it in diagnostic mode and saw no stored fault code

- in diag mode 01, throttle closed read 15 (fsm calls for 12-22). Throttle fully opened read 103  (fsm calls for 97-107). So everything is within spec and the throttle moves smoothly and nicely from 15 to 103.

Back to square one.

Any other suggestions?

Thank you!

Mike

 
dcarver, thanks for the link, I'll check it out. What's still weird is that it happened ONLY after filling up and once it's cleared (this time it took 25 miles), it never happened again until next fill up.

I think I'll go fill up tonight on my way home. That'll be ~50 miles since my fill up this morning and see if the same symptom happens.

 
Just ran through some diagnostic from the FSM. 01 (TPS), 13 (throttle signal 2),14 (accel signal 1),15 (accel signal 2) and they all within specs. Also ran diag on the 4 fuel injectors (diag code 36, 37, 38, 39) and they all fired up clicking 5 times as expected.

 
This is just weird.  I'm not completely familiar with the idle circuit on the Gen 3+.  Is it all controlled by the ECU?  If so, it almost sounds like you have an ECU issue.  That's all I can come up with.

 
Have you addressed the possibility of a bad plug, bad COP or bad connection to the plug?  I don't think you can totally rule out the possibility of a bad TPS or even a MAP sensor.  Even an O2 sensor giving the wrong data to the ECU could be problematic.  In the absence of a "smoking gun" (i.e. leaking vacuum line) these things can be difficult to diagnose.

 
After the engine warms up your bike should idle around 1K rpm. There is an adjustment screw on the right hand side kind of hidden away next to the lower part of the tank.

I didn't read every freakin thread so maybe I missed you correcting this issue first off.

Good luck, Dave

 
Again, I can't see where you have tried to eliminate the cause of the problem being a fuel venting issue from fuel at the top of the fuel tank after fill up?

Things could be normal now just recently because you have 50 miles of fuel burned off and the venting issue is no longer there until you fill up again.

Repeating my suggestion:  You are at 50 miles on the tank - lets call that 1.25 gallons burned (more or less).  Burn off 2-3 gallons more.  Then go to the gas station and put ONLY about 2 gallons in it.  Report back if the problem repeats itself.  If it DOES NOT, then do not assume you have figured it out.  Burn off 2 gallons and then put 2 gallons in it again.  Confirm you can duplicate the problem under a controlled condition.  Then return and fill up the bike all the way and if the problem repeats itself, THEN you know where to start digging deep to find the problem.

Another thought - after you have confirmed that the problem does not duplicate on partial filling of the tank, return to the gas station and start adding a 1/4 gallon of fuel to the tank and try to get the problem to repeat itself.  Keep adding a quart until it happens.  Take note of that level and use that as a gage to see what's happening with the venting system at that level.

Of course, if the problem repeats itself at any point with a partial fill up, then at least we have eliminated that and now have to dig further into the issues described above.

The bike is inherently so dog gone reliable, we are likely going to learn that this is something very simple.  A piece of crap in the tank vent - like that simple.

 
 It is very difficult for us to diagnose a problem remotely unless someone has actually experienced it and solved it in the past, so we are just guessing, but I agree with Pants that I don't think you have ruled out a tank venting issue thoroughly. Have you read up on how the charcoal canister works so you understand where and how to verify that it is working properly? The hard part is to take off enough of the covers on the FJR so you can follow the hoses and see which ones go where. 

While you are poking around, verify the electrical connections to the fuel pump.   

 
I had a similar issue a couple of years ago. Turned out to be a hole in a vacuum line that went to the fuel rail. When I fixed that, the bike ran normally again. Check the lines or just simply replace them. A pretty easy fix and good preventative maintenence for old lines anyway.

 
Thank you all and I truly appreciate all your inputs.

- Is the tank venting this tiny holed rubber under the cap? From the FSM, I saw there are only 2 hoses coming from the tank: 1 is for overflow gasoline to run to the ground and 1 goes to the charcoal canister. I'm going to remove the hose from the canister and use my air compressor to blow air in it to see if it's vented all the way to the tank.

- I will try to not fill to the top on next fill up. Thank you hppants.

- Now more and more sounds like a venting problem, as the electrical seemed to be all checked out fine (by the way, it's so awesome to have onboard DIAG mode built-in on the dash from Yamaha engineers. I could even run it without getting off my FJR's seat! On a BMW one needs a $500+ tool to do what we do for free. But Yamaha removed the DIAG on all models after 2014, right? They must hired an ex-BMW manager)

 
Just checked the tank vent hose to canister. No obstruction.

Got to love the built-in DIAG mode. I ran through all the codes from the FSM and everything passed, except code 67 has a 02. It's "idle speed control learning" and looking up 02 in the FSM and it said "need to erase ISC learning number". Wow. To erase, it said hit "stop-start" 3 times within 5 seconds" and the code was cleared to 0 and the computer relearns. Cool. May be this is related to my hiccup. We'll see.

 
Thanks Bounce, for the link. Appreciate it.

I just used my air compressor to blow the 2 vent hoses and air came out normally. I'll revisit.

 
Sorry for being late to update, I didn't ride much since my last post. Here is the latest:

_ I refilled twice since my last post

- 1st refill: after riding 250 miles, as usual, without a single incident (except the problem that happened immediately after the previous refill). Opened then closed gas cap without refill, restart, no problem.  Refilled with only 3 gallons (Instead of almost 6), start and it died as before. Tried a few times, same thing. Held the throttle to keep the rpms up and rode away. After 5 minutes or so, it was back to normal for the rest of the tank again.

- 2nd refill was yesterday after riding until the low fuel warning flashed. This time, I refilled it all the way full to the bottom of the neck as before. Start and no problem! It idled perfectly at the 1st start. 

Now I don't know what the conclusion is. Nothing else changed ever since the problem started except that I now temporarily bypassed the canister (but the same problem persisted right after I bypassed it so that's inconclusive)

Thank you all.

 
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