Desperate for help: Bike starts stuttering after a while - repairs itself by turning engine off and on again

jaffabaffa

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Yes, I removed the extra fuel filter.

The more I think about it, the more I am actually starting to consider the possibility that my local Yamaha dealership didn't really replaces the TPS like the said they did. I know it is hard to believe, but theoretically it is a possibility. They make virtually no money at all on recalls I guess, so who knows. I might actually just buy a new TPS myself, and install it myself, just to be 100% sure that the TPS is not faulty.

I can buy an OEM Yamaha TPS for about $225,- but I can also buy a Chinese remake TPS for about $60,-

Any of you guys have any experience with those cheaper Chinese TPS units?
 

Motogiro

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That is very smart idea!
In case replacing the fuel pump en thoroughly cleaning the inside of the fuel tanks does not fix the problem, I will try doing that as a last resort.
Thanks for the help!
Keep in mind that when you bypass that fuel pump/injection relay you are bypassing safety protocol that module provides. So I'm recommending this as a test , hoping you will be cautious in regard the putting the side stand down and not having the bike in neutral with the clutch out.
 

Gary in NJ

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Correct, I was thinking of the CPS (crank). The TPS is evaluated through a sweep and verifying the results.

A faulty TPS would not result in a bike that would become unridable after 5 miles of riding. A faulty TPS usually manifests as an idle that is inconsistent. If it effected riding at all, it would be from a closed throttle position to a slightly cracked-open position.

With that said, most of the data points we have are a result of the TPS recall. A completely failed TPS may present differently.

Perhaps it might be worthwhile for the OP to perform a throttle sweep when the engine is warm but not showing signs of the problem, and then again right after the problem re-emerges. This way he won’t be guessing at the problem.
 
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TownsendsFJR1300

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Clogged tank vent can also cause similar issues.

Plus 1 ^^ and the fuller the tank, the quicker the issue will happen.

If you raise your tank up, the vent line, that runs down the left side of the bike, tends to kink.
Simply reaching thru the frame and where it exits (lower right side) and gently pulling will open it back up..
 

jaffabaffa

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@TownsendsFJR1300 @Gary in NJ @trepetti @Macconraoi @Motogiro

Hey guys!

Thanks a lot for all the help so far!

I have a little update on the matter, followed by a small question. I have discovered an interesting fact that could really narrow down the search.

So yesterday something interesting happend. I was slowly pulling away from a roundabout to around 90 km/h (55 mph) when all of sudden the bike lost pretty much all its power. I went and pulled in the clutch, with the intention of listening to the bike at idle RPM. As soon as I pulled in the clutch, the engine completely shut of (stopped running). After this had happened, I slowly disengaged the clutch again, and the enige turned right back on, with all it's power fully restored.

So, why is this fact interesting?

This discovery pretty much rules out any ECU restart/rebooting theories, as well as my own theory on the fuel pump doing its thing.

So, pretty much we know this so far:

  • It has nothing to do with temperature or certain parts getting warm or cold, since the bike is capable of fixing itself in a mere second (at any temperature).
  • It has nothing to do with the ECU restarting or rebooting, since the bike is also capable of fixing itself by intentionally letting the engine stall, and then bump starting the engine on again.

First of all, do you all agree with these statements?

if so, do you guys also agree that the problem must have something to do with ventilation of the fuel system, or a vacuum being created somewhere?

I came across this very interesting topic on another forum:


This guy had a similar problem. It turned out to be his charcoal canister. It is known that not all versions of the FZ6 are equipped with such a charcoal canister. my bike is a European version. A Dutch version to be more specific.

Do you guys happen to know whether or not my bike has a charcoal canister?


Looking forward to your reactions and answers! I will keep you guys updated!
 

jaffabaffa

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@TownsendsFJR1300 @Gary in NJ @trepetti @Macconraoi @Motogiro

I used a compressor to blow air through these two black hoses exiting the fuel tank. I also blowed air in the red coloured rubber under the fuel cap. All the air exited through the nipple underneath the tank.

Nothing came out of any of the hoses. No debris or filth or anything.

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Also, today something interested happened again. When I went full throttle in second gear, the bike started to lose power at around 1000 RPM before hitting the redline. Even though I kept applying full throttle, the bike wasn't apple to spin up till the redline. When I rolled back on the throttle, the bike regained power again, and everything seemed fine. After I had noticed this, I turned the bike off and on again, and went full throttle right away. The bike revved up straight into the rev limiter. Also, it had noticeable more power at the top.

What did I learn of this?

The degree in which the symptoms can occur is variable. The bike can either lose all power and stall, or only lose (a little) power at the top of the rev range.


Any further ideas or suggestions?
 

TownsendsFJR1300

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If you have correct fuel pressure at the rail, to rule out a tank venting issue, ride the bike with another key in the tank, cracked open.

At this point, I don't think the above is your issue but something electrical. Either a bad connection somewhere or again, a badly failing TPS (which you mentioned earlier, may NOT indeed have been changed)..

Did you go thru the dash/TPS and do a throttle "roll on" check looking for missing/skipping digits?
I hate throwing parts at an issue but a known bad TPS issue may still haunting you..

I would go thru ALL the connectors again, besides looking for corrosion but a wire potentially pulled out slightly..

It wouldn't hurt by passing all the safety switches including the side stand, clutch switch (likely not an issue) and the Red kill switch (forgot if you already did that..) The side stand switch, IF activating when it shouldn't, WILL kill the engine..

Is any of your dash cutting out/flickering when the engine acts up?
 

jaffabaffa

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If you have correct fuel pressure at the rail, to rule out a tank venting issue, ride the bike with another key in the tank, cracked open.

At this point, I don't think the above is your issue but something electrical. Either a bad connection somewhere or again, a badly failing TPS (which you mentioned earlier, may NOT indeed have been changed)..

Did you go thru the dash/TPS and do a throttle "roll on" check looking for missing/skipping digits?
I hate throwing parts at an issue but a known bad TPS issue may still haunting you..

I would go thru ALL the connectors again, besides looking for corrosion but a wire potentially pulled out slightly..

It wouldn't hurt by passing all the safety switches including the side stand, clutch switch (likely not an issue) and the Red kill switch (forgot if you already did that..) The side stand switch, IF activating when it shouldn't, WILL kill the engine..

Is any of your dash cutting out/flickering when the engine acts up?


Thanks for the reply!

I already went through the dash/TPS and did a throttle "roll on" check. No digits were missing or skipping whatsoever.

I already tried opening the fuel cap after the the issue occurs, but I have yet to try riding off with an open fuel cap right from the get go.

Bypassing the kill switch and side stand switch would indeed be a logical next step.
I found this post on Reddit from a guy with the EXACT same issue:


It turned out to be his ignition switch. (Might he have meant kill switch, as opposed to his ignition switch?)

If those things don't turn out to be the solution, I have yet to try cleaning the fuel tank and fuel pump mesh.
 

Motogiro

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What did I learn of this?

The degree in which the symptoms can occur is variable. The bike can either lose all power and stall, or only lose (a little) power at the top of the rev range.


Any further ideas or suggestions?

Let's back up a little. Have you confirmed that the pump is delivering proper fuel pressure and has continual power? Since this is an intermittent you want to be able to monitor what occurs during the failure. If we suspect it's a fuel problem we should eliminate the possibility it is actually a fuel issue.
 

jaffabaffa

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I have not yet been able to determine whether or not the fuel pump is faulty, since the bike can not be plugged into a computer. I have Idea no on how I can somehow monitor the fuel pressure while the bike is running.

I doubt the fuel pump is bad, but the fuel pump mesh might very wel be badly clogged.
 
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TownsendsFJR1300

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I have not yet been able to determine whether or not the fuel pump is faulty, since the bike can not be plugged into a computer. I have Idea no on how I can somehow monitor the fuel pressure while the bike is running.

From post #12 earlier:

Check page 7-29 in the S1 Yamaha shop manual for pressure testing.

I believe you now have the shop manual as a PDF and can check the procedure..
You don't need a computer and the bike HAS to be running to check it..
 

jaffabaffa

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From post #12 earlier:

Check page 7-29 in the S1 Yamaha shop manual for pressure testing.

I believe you now have the shop manual as a PDF and can check the procedure..
You don't need a computer and the bike HAS to be running to check it..


Thanks a lot! I will look into it!

Any specific pressure gauge you can recommend me to buy?
 
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jaffabaffa

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Hey guys,


Small update.

Today I removed the fuel pump assembly from underneath the tank. This is what I encountered:

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Looks pretty horrendous to me. What do you guys think?

I have rust remover by Tank Cure in the tank right now.

1631913790526.jpeg

I'ill leave the rust remover sitting in the tank over night, and will continue working on the bike tomorrow.

I do have another question though.

Can I connect my new fuel pump to the wiring loom, so I can test if its starts to prime when I turn on the ignition? That is without it being in the tank, or being in any fuel for that matter. Is that oké, or would that possibly damage the pump, or confuse the ECU?

Many thanks!
 

TownsendsFJR1300

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Wow, that's REALLY BAD..

And yes, that would in-deed cause some running issues.

As the pump would run at "key on" and pump till primed/pressurized line,
I don't know if the pump would keep running (there's no build up of pressure) .
It wouldn't hurt the pump(or bike) for a second or two of running. But I'd be quick to turn off the key.

If your old pump primed, and it sounds like it did, you know the wiring is fine.
If you really want to check the new pump, I'd just run 12 volts to it for a second..

The old assembly is most definitly an issue
 
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trepetti

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There is NO WAY that pump screen would allow enough fuel flow to keep up with demand! When troubleshooting I rank things into:
Obvious
Probable
Possible
Unusual

Your pictures all rank as Obvious. I think you found the issue.
 
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