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Sporadic hesitation, need ideas.


dehning

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Hi all, I've had my '02 XX for 5 years now, love the thing to death. I have put about 15,000 miles on it, the vast majority of which is commuting. In the last few days something a little troubling started. Last week on the way home it lost engine power for about 1/2 a second, it came right back and was fine the rest of the way home. This morning I was about 10 miles out and it did it again twice, separated by about a minute. Not wanting to risk being stranded, I turned round and went home to swap bikes, it never hesitated once on the way home.

I have racked my brain about what would cause this and I am looking for any ideas, here are some notes/points:

* I have not changed anything whatsoever on the bike in a couple thousand miles now (short of an oil change and chain lube)

* Bike has ~29,000 miles on it.

* It has happened at 95 and 75 degrees fahrenheit (I'm in Texas). No water/rain whatsoever.

* The clock/trip meter doesn't reset when the hesitation happens and there is no misfire.

* I have a Power Commander III-USB with a custom tune for my setup (K&N air filter and full Yoshi 4-1 system)

* I'm still on the original battery that came with the bike which cranks easily and the bike starts easily.

* I never ever push the bike, you could call it "babied", it sleeps inside a garage.

Please give me some ideas, right now I have the following suspicions:

* Bad power line to PC3

* Oxidization inside the plugs of the main harness.

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Lost engine power or all power including electric?

Lights go out or dash blink out?

Know you mention the trip meter not resetting but wondering about lights

Only engine power for 1/2 a second, all other power stayed working fine. Dash didn't change.

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Just a hunch... Check your vent lines for raw fuel - they should be dry. If not, the FPR diaphragm could be compromised (pin hole will sometimes manifest similar symptoms - at first... unfortunately, it'll only get worse). The good news is that it's an easy fix; just replace the FPR (on the right end of the fuel rail).

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Just a hunch... Check your vent lines for raw fuel - they should be dry. If not, the FPR diaphragm could be compromised (pin hole will sometimes manifest similar symptoms - at first... unfortunately, it'll only get worse). The good news is that it's an easy fix; just replace the FPR (on the right end of the fuel rail).

Wow, and this would cause this VERY sporadic issue ? With all my playing with these things I don't think I've ever messed with an FPR.

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I don't have a lot of experience with the FI bikes but lose of engine power only sounds like a fuel issue to me.

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Just a hunch... Check your vent lines for raw fuel - they should be dry. If not, the FPR diaphragm could be compromised (pin hole will sometimes manifest similar symptoms - at first... unfortunately, it'll only get worse). The good news is that it's an easy fix; just replace the FPR (on the right end of the fuel rail).

Wow, and this would cause this VERY sporadic issue ? With all my playing with these things I don't think I've ever messed with an FPR.

It starts out as sporadic... but it can end up with a hydro-locked engine. Fuel leaks through the compromised FPR into the vent lines and then into the cylinders. That alone can hydro-lock a cylinder. Or even worse, it'll find its way past the rings and into the crankcase. It mixes with the oil - leak enough volume and it can hydro-lock the bottom end.

It's one of the few things on a FI XX that may become a problem thanks to ethanol blended gasoline. It appears the FPR's diaphragm may be susceptible to deterioration when subjected to prolonged exposure to ethanol. It's happened to a number of folks on this board.

OTOH, your Power Commander could be wonky... or both... shit happens.

At least check the vent lines, if for no other reason than to eliminate the FPR as the problem.

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So is that FPR part number 16740-MAT-E22, or number 18 in this diagram:

(Also, could somebody explain the mechanics of how fuel from a fuel pressure regulator ends up in a vent line ? They don't seem like they should be linked ?)

MAT4E1802C.gif

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So is that FPR part number 16740-MAT-E22, or number 18 in this diagram:

(Also, could somebody explain the mechanics of how fuel from a fuel pressure regulator ends up in a vent line ? They don't seem like they should be linked ?)

MAT4E1802C.gif

Right! Part 18 is the FPR...

There are two lines attached to the FPR. One, on the underside as you view it from the right side if the bike, is a vacuum (vent) tube on the outer cap of the FPR; the other is the (larger diameter) fuel return line that's located past the FPR's rim, aimed aft, and closer to the fuel rail.

That (smaller diameter) vacuum line leads to a series of collateral lines that connect to the throats of the throttle bodies. In my shop manual ('99-2000), it's clearly depicted on page 5-62 (Throttle Body Vacuum Tube Routing). Of course the California bikes have additional vent/vacuum lines that connect to the EVAP purge control valve and the CARB mandated canister.

I'm aware that after '99, there were some small changes - yours is an '02, so the vacuum line routing is a bit different.

Maybe you didn't know we have a shop manual ('99-2002) available on this site... http://www.cbr1100xx.org/forums/index.php?showtopic=32678

It downloads as a PDF file. It's an extensive (146.32Mb) file so be patient. You'll need to see the diagrams on pages 5-72 and 5-73.

If your vent/vacuum lines are internally dry your FPR is probably fine... if not, that is a problem you can nip in the bud.

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I think it's the Power Commander. Dis-connect it from the system and ride it for a while. If the symptoms don't return...............

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OK I think I get the vacuum hoses, I will check for fuel in them.

I'm not so sure of the PC3, seems too sporadic?

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OK I think I get the vacuum hoses, I will check for fuel in them.

I'm not so sure of the PC3, seems too sporadic?

Takes 3 minutes to disconnect the PC3 and take it out of the equation... why not do that first? It's possible that when it gets hot it has problems... a few seconds is probably all it needs to reboot itself.

Yep.. check for bad ground/loose wiring. Also, check the bank angle sensor under the seat.

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I will check PC3 (It's a lot longer than 3 minutes to get to that plug though)

I was riding smooth and flat so I don't think it's the angle sensor, I've had one of those go out and the problems are much more noticeable, not 3 misses in 20+ miles.

Like I said in the original post, this is drought stricken Texas, bike hasn't seen water for months.

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