FJRiders.com

Did one more cleaning this morning before work, and ran a few test cycles. YouTube is taking it's time to make them all playable so if it doesn't work, try again later.

Idle Speed Test




Acceleration Test




Variable Speed Test




Medium Speed Test




Looks like they are coming in pretty well.

Silverback, no OBD port on a Gen 3, coils are on each plug, so no wires.

I would say that you are done! What little differences remain will likely disappear with a few tanks of fuel. If it was me, I think I would drop these four injectors and the new fuel rail in and give it a try.

If this doesn't do it, I guess there could still be a problem with the fuel pump/pressure regulator or the TPS could be bad (I know that was replaced earlier). Note: In addition to the TPS (#12 in the attached fiche), there is also an "Accelerator Sensor Assembly" (21 in the fiche).
https://www.partzilla.com/catalog/yamah ... g/intake-2

I also noticed TWO pressure sensors on the Gen III (#14 in fiche)...

FJRoss wrote: ↑Sun May 29, 2022 8:39 am I would say that you are done! What little differences remain will likely disappear with a few tanks of fuel. If it was me, I think I would drop these four injectors and the new fuel rail in and give it a try.

If this doesn't do it, I guess there could still be a problem with the fuel pump/pressure regulator or the TPS could be bad (I know that was replaced earlier). Note: In addition to the TPS (#12 in the attached fiche), there is also an "Accelerator Sensor Assembly" (21 in the fiche).
https://www.partzilla.com/catalog/yamah ... g/intake-2

I also noticed TWO pressure sensors on the Gen III (#14 in fiche)...

Yep, 2 pressure sensors, one is atmospheric pressure and not hooked to anything, just open.

He replaced the Accelerator Sensor as well. In short, from memory, new plugs, 1 new coil (happened before and after coil replacement. Coil didn't fail, he just didn't like the condition of the rubber boot ), new TPS, new Acceleration Sensor, new fuel pump/filter. I can't think of anything else that we've done or he's replaced, off the top of my head.

Another whack at it with no results. Viper Dad picked up the cleaned injectors and fuel rail, put that on and went for a test ride. Nothing changed. So add swapping out the fuel rail and injectors with no improvement.

We're trying to do the tank swap but that's going to take some time to get to. He's busy and I'm 90 hours a week at work so finding time for that is our next challenge.

I truly hope this gets figured out, sooner rather than later.

Disappointing!!

If the tank swap doesn't do it, I guess you are down to a bad replacement TPS, a leaky throttle body boot (easy to happen) or an air leak somewhere (vacuum hose)? If the tank does it, then I guess you will be looking for a replacement fuel pump.

Do you have any way to measure the fuel pressure on the rail - especially while riding?

Good luck!

Viper Dad dropped his bike off with me as our schedules are just too different right now and I'm determined to fix this issue so he can have a smooth running bike again.

I had to move it about 30 ft from where he left it for me. I started it and first thing I said in my head was "that doesn't feel right". Something about the idle just felt rough to me. I texted that to him and he said it felt fine to him and he never noticed it. I wonder if that's a symptom or just something I'm imagining in my head.

One other thought hit me. What about the O2 sensor?

My plan, as of right now, is to pull it apart and verify everything. Verify all connections, plugs, fittings, seals, etc, so I can check them off one by one. Also, tank swap as well.

At least for a Gen II, a warmed up bike runs OK without the O2 sensor hooked up. (For the Gen I and Gen II bikes, Dynojet recommends disconnecting the O2 sensor when installing the PC.)

I had an experience where the wire for the O2 sensor got mashed between the timing cover and the case. Theory is that the O2 sensor was giving a WRONG signal instead of either the right signal or no signal.

Couldn't prove anything for certain, but the bike was running horribly after a service that included a CCT replacement and got immediately better after I discovered the mashed wire (presumably shorted to the case) and restored the insulation. Like magic. If the Gen III doesn't lose its mind without the O2 sensor, I would try unplugging it.

(I was concerned that we had messed up the timing)

Idle issue in 30 feet.... well, that could just be because it wasn't warmed up and that should all go away.....
I'd still do the tank swap before I tore into a list of I dunno's... you had some indication that was the ticket, so I'd prove that one way or the other first.

When you get this fixed, I'm going to miss reading this thread. I love a good mystery.

FJRPittsburgh wrote: ↑Fri Jun 17, 2022 5:59 pm When you get this fixed, I'm going to miss reading this thread. I love a good mystery.

It's turning into Lord of the rings. The orcs are circling around precious

bungie4 wrote: ↑Fri Jun 17, 2022 6:31 pm

FJRPittsburgh wrote: ↑Fri Jun 17, 2022 5:59 pm When you get this fixed, I'm going to miss reading this thread. I love a good mystery.

It's turning into Lord of the rings. The orcs are circling around precious

They stab it with their steely knives but they can't kill the beast!

Well….. took my first ride on it today. Ride for 15-20 minutes and could maybe feel a super slight surging but hard to tell. Could have just been the road, it was that faint. About 2 blocks from home, in 2nd, I slowed to turn right and it was a quite violent jerking. Definitely a “holy shit” moment.

That’s definitely not a fuel tank swap issue. That’s something else. Went through it methodically, pulled the plugs, checked them. 1 was open wider than the rest and outside of spec but I don’t think that was it. Pulled the throttle bodies off and cleaned them. All the little ports next to the rubber caps seemed dirty. Cleaned everything up and then shoved the camera down the intake.

1st valve on left hand side pretty caked with carbon. Ever other valve looked pretty clean. Something is happening to that first valve for sure.

Put it all back together and swapped the coils around.

Ride it again and it’s there almost all the time and I’m changing the dialogue. To me, it’s not a surge, it’s a miss.

I’m going to swap my coils and his and see if that changes anything. Definitely feels like a miss to me.

Arrgh!!
I wonder if that first intake is crapped because of an earlier injector problem?
Have you done compression and leakdown? (I can't remember)

Seems less likely to be a tank issue.

Coils - I really doubt the plug is the issue
TPS (I know it was replaced)
Compression...

?????????

Maybe dumb questions if I've missed stuff in the 8 pages of this thread but anyway...

Can the condition be duplicated on the centerstand? Has anybody put a meter or scope on this bike to look at sensor/output voltages or patterns? Do Gen3 bikes have an OBD port that a device can be plugged into to look at live data?

Swapped the coils and I’d say if it’s not gone, it’s very close to gone. If it’s still there, it’s so minor I can’t tell if it’s the road or the bike. I rode it for 30-35 minutes and never felt any bucking and it seemed like it might be gone. On a scale of 1-10, 10 being the worst, I’d say if it’s there, it’s a 1 now.

I left my coils in his bike and put his in mine but haven’t ridden mine yet. I’ll let him take it and see if his is fixed or might is now broken.

Any way to check a coil? At $150 each, it would be nice to know which one is bad instead of trial and error replacement.

No ODB.

I don’t have a scope or know how to use one.

Festus wrote: ↑Sat Jun 18, 2022 5:17 pm Swapped the coils and I’d say if it’s not gone, it’s very close to gone. If it’s still there, it’s so minor I can’t tell if it’s the road or the bike. I rode it for 30-35 minutes and never felt any bucking and it seemed like it might be gone. On a scale of 1-10, 10 being the worst, I’d say if it’s there, it’s a 1 now.

I left my coils in his bike and put his in mine but haven’t ridden mine yet. I’ll let him take it and see if his is fixed or might is now broken.

Any way to check a coil? At $150 each, it would be nice to know which one is bad instead of trial and error replacement.

Four for $80

https://www.ebay.com/itm/165492685376?h ... Sw94Ba82tf
Free shipping...

Rode my bike with his coils in for about 20 minutes. Smooth as silk. No transfer of the issue.

Where are the coils getting their juice? And how do I check that? Maybe it’s further upstream than we are thinking.

Festus wrote: ↑Sat Jun 18, 2022 7:30 pm Rode my bike with his coils in for about 20 minutes. Smooth as silk. No transfer of the issue.

Where are the coils getting their juice? And how do I check that? Maybe it’s further upstream than we are thinking.

Maybe just a connection to the coil-on-plug?
I still want to know why that intake was crapped up. If carbon due to a leaky injector, it may eventually clear itself.

If you haven't done it, I think it needs a compression/leakdown test.