Baffling FPR...
 

Ok guys , this is starting to become one of those gremlin chases that seems to never end and I could really use a fresh look on this.

I'm a fairly competent mechanic and I work on a diagnose and cause elimination process so, buying stuff and hoping to fix it is not an option.

Take in consideration that the bike starts, runs and pulls as new apart from a slightly erratic idle -1200 to 2000

-Here's the deal, I notice a small smell of gas when the bike was idleing but there was no blue, white or black smoke coming from the exhaust.

-Checked my oil level - it was higher than before, so I assume some "extra" gas was being dumped in the cylinders.

-Took tank off to check the FPR, vaccum hoses and plugs

-Testing FPR/Injectors leak : without the airbox, wide open throttle while ignition was off, then turn ignition on to see if any gas dribbled down the injectors = No dribble

-Removed vaccum hose from FPR and it was completly dry
Blow and sucked on the vaccum hose and seems good, it's completly sealed

-Started bike with vaccum hose off the FPR and no gas came out

-Installed hose, started bike, give her a few revs while looking at the intake and the injectors seems to be putting out the same amount and same spray pattern of gas

-Removed plugs and they were all dry, no soot and tanned looking

BUT there were 2 plugs with the terminals sligthly rusted: *1plug and coil and *3 plug and coil

NOW here's my doubts:

*Can a weak sparking plug not burn the gas being dumped and allow it to run down to the crank?

*Is it possible that the FPR only fails and dumps more gas to the injectors when the bike is running?

*Will a clogged Fuel Return Hose forces the FPR to fail under load?

*How could there be gas in there unless the FPR was bad, even if it seems to be ok?

So guys if anyone as experienced anything like that or has had some FPR problems or new insights please share them, I'm open to suggestions and mechanical know how :icon_teeth:

T.I.A.

Come on guys, nobody?

when i got my bike i had the same problem..
could smell gas at idle
no smoke
vacuum hose dry, not filled with gas
bike ran ok but i could tell it wasn't running like it should...it just didn't seem like it had as much power as it should have wile riding...
i didn't go into detail testing like you did...
i got a new fpr, changed the oil... gas smell went away and bike ran a lot better...
have not had the same problem again since.. but that was a year and a half ago...

So you didn't had smoke coming out and your vaccum as still dry?
Just like mine, but I do not feel any kind of power loss, she still gives everything she has...

And I do feel some very slight power surges below 4k under steady throttle

yes, no smoke, vacuum is dry..
after reading about the fpr problems in other threads and as many forums as i could find it kinda seemed like thats what it was but not all the problems fit... so i took a gamble and glad i did...i think it cost me about $80 for new one.. but after i installed it i could tell thats what the problem was...

at low rpms from steady throttle to wide open it struggled a bit.. not like it was off time but like it was getting flooded...

i am no expert thats why i come to the forums for more info.. but it sounds like it is your fpr to me...
i would guess the spring inside the fpr is just a little week but the seal is not busted since there is no gas in vacuum hose... just a guess...

That's one of the things that's leaving me baffled, she has no power issues at all.
But common sense tells me that in reallity it is the FPR. Maybe it's just the beginining of failure and it still doesn't flows enough to be noticeable while riding...weird.

The truth is that she's getting gas in the oil, and that's a big no-no.

It all leads to it, but my testing did not showed me clear indication of that being the case :icon_screwy:

I'm getting really :icon_rant:with this... and the sun is shining around here

I think I'm gonna take the FPR apart and check for visual signs of detioration and check the spring itself.
I really don't now how to check the spring but hey, I gotta try :icon_teeth:

I forgot, did you check your plugs and boots when you had that problem?
How did they look like?

the only thing i checked was the vacuum hose.. thats what others were telling me, that and gas in the oil, or smell of gas in exhaust...after i herd that i figured if nothing else at least that was one less problem to worry about...lol...
when i looked at my old fpr it looked just like the new one the spring seemed fine and the seal wasn't broke.. i was just as confused as you are...
might be early warning stage of it going out and most riders don't notice till it does need to be replaced... i have no idea.. i do know that after i replaced it the gas smell from exhaust went away, oil didn't smell like gas, and i had a little more power under load...

I took a look at it and it looks just as new like you said, no tears in the diaphragm and the spring as good tension on it...:icon_shrug:

Come on, black should be black and white should be white not whitish black! ARRRRRRRRRRRRGGGGGGGGGG