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Thread: 2004 RSV Tuono backfiring after fuel pump line replacement

  1. #1
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    2004 RSV Tuono backfiring after fuel pump line replacement

    Hey folks,

    My 04 RSV Tuono blew out its high pressure fuel line recently and I replaced it with the OEM part, and did the fuel filter and line to the outside with the parts from AF1 Racing. Since I've done that, it's taken to backfiring loudly on a slight bit of throttle opening.

    In trying to resolve this, I've checked all the fuel lines and checked all the vacuum lines for leaks. None visible. I've replaced the air filter with a K&N (it was due), and pulled out the bung from the intake (ram air ducts side). I replaced the airbo gasket in case there was an air leak (it was a bit worn anyway).

    The bike is definitely running richer... you really notice it at idle where it smells rich. I checked the idle air bleed screws and they were both a half turn out from fully tightened, which didn't seem enough, so I've pulled them both out to 1 1/2 turns - its smoothed out the bike a bit in the lower range but the idle still varies a bit and occasionally at idle (especially when cold) you'll get this hiccup from the engine, and a little "puff" sound fropm the exhaust - too much fuel I reckon.

    Fuel consumption is up a bit - 180kms to warning light, when I used to get about 205 - 210kms.

    I've thrown it into diagnostic mode and there's no codes. Throttle position 0 when throttle closed and 1 when you open it.

    Any thoughts here? I'm leaning towards either:

    a) the O2 sensor isn't reporting right; or
    b) the problem with the fuel line had been around for a while and the previous owner has tuned the bike by tweaking the two potentiometer screws in the ECU to compensate and now the fuel pump is working fine it's too rich.

    The performance of the bike when off idle is astounding - it will easily loft the front wheel in third gear at speed limit (its geared 15F 44R) - so this issue is only affecting the idle and when decelerating - the backfires are pretty loud - if it was just popping loudly I'd have no issue.

    Obviously my throttle bodies aren't sync'd, and that is having an effect on the ropey idle, but I can't see how that could be causing the backfiring, and besides, it did that before I changed anything anyway.

    Cheers guys.
    And I to my motorcycle parked like the soul of the junkyard. Restored, a bicycle fleshed with power, and tore off. Up Highway 106 continually drunk on the wind in my mouth. Wringing the handlebar for speed, wild to be wreckage forever.

    - James Dickey, Cherrylog Road.

  2. #2
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    Quote Originally Posted by riffer View Post
    Hey folks,

    My 04 RSV Tuono blew out its high pressure fuel line recently and I replaced it with the OEM part, and did the fuel filter and line to the outside with the parts from AF1 Racing. Since I've done that, it's taken to backfiring loudly on a slight bit of throttle opening.

    In trying to resolve this, I've checked all the fuel lines and checked all the vacuum lines for leaks. None visible. I've replaced the air filter with a K&N (it was due), and pulled out the bung from the intake (ram air ducts side). I replaced the airbo gasket in case there was an air leak (it was a bit worn anyway).

    The bike is definitely running richer... you really notice it at idle where it smells rich. I checked the idle air bleed screws and they were both a half turn out from fully tightened, which didn't seem enough, so I've pulled them both out to 1 1/2 turns - its smoothed out the bike a bit in the lower range but the idle still varies a bit and occasionally at idle (especially when cold) you'll get this hiccup from the engine, and a little "puff" sound fropm the exhaust - too much fuel I reckon.

    Fuel consumption is up a bit - 180kms to warning light, when I used to get about 205 - 210kms.

    I've thrown it into diagnostic mode and there's no codes. Throttle position 0 when throttle closed and 1 when you open it.

    Any thoughts here? I'm leaning towards either:

    a) the O2 sensor isn't reporting right; or
    b) the problem with the fuel line had been around for a while and the previous owner has tuned the bike by tweaking the two potentiometer screws in the ECU to compensate and now the fuel pump is working fine it's too rich.

    The performance of the bike when off idle is astounding - it will easily loft the front wheel in third gear at speed limit (its geared 15F 44R) - so this issue is only affecting the idle and when decelerating - the backfires are pretty loud - if it was just popping loudly I'd have no issue.

    Obviously my throttle bodies aren't sync'd, and that is having an effect on the ropey idle, but I can't see how that could be causing the backfiring, and besides, it did that before I changed anything anyway.

    Cheers guys.
    So the problem was there before you changed filter and air bleed screws? Is it worth syncing the inlets? That sounds a good place to start- playing with the air bleed screws without doing this could be the issue?

  3. #3
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    post on the AF 1 forum
    Bet someones had this happen previously.
    I'd put money on one of your vac hoses being off
    RSV Mille: No madam, its an Aprilia, not a Harley. If it were a Harley, I would be pushing it !

  4. #4
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    Quote Originally Posted by frogfeaturesFZR View Post
    post on the AF 1 forum
    Bet someones had this happen previously.
    I'd put money on one of your vac hoses being off
    You'd think so eh, but I'm damned if I can find anything wrong with the stupid thing. I've also posted on the AF1 forum too, cheers.
    And I to my motorcycle parked like the soul of the junkyard. Restored, a bicycle fleshed with power, and tore off. Up Highway 106 continually drunk on the wind in my mouth. Wringing the handlebar for speed, wild to be wreckage forever.

    - James Dickey, Cherrylog Road.

  5. #5
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    Quote Originally Posted by SVboy View Post
    So the problem was there before you changed filter and air bleed screws? Is it worth syncing the inlets? That sounds a good place to start- playing with the air bleed screws without doing this could be the issue?
    Yeah, the problem occurred as soon as I put the immersion fuel pump back in the tank and connected everything back up again. Playing with the air bleed screws has been an attempt to get the idle fuel mix back to something a little less rich. I've put it back to where it was originally (always write down what you had previously so you can go back to it) but its so damned rich it's not funny.
    And I to my motorcycle parked like the soul of the junkyard. Restored, a bicycle fleshed with power, and tore off. Up Highway 106 continually drunk on the wind in my mouth. Wringing the handlebar for speed, wild to be wreckage forever.

    - James Dickey, Cherrylog Road.

  6. #6
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    Any luck diagnosing this? Any fault codes?

  7. #7
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    Okay...

    after two months of trying all sorts of things, testing all the lines, playing about with the idle air mix, and feeling like I was gonna have to give in and give it to the shop I've finally found the problem...

    The giveaway was the vacuum lines on the gear lever side of the bike. If you squeezed the vacuum line for the rear cylinder the bike would die. But the front cylinder line... nothing. So there had to be some air getting in to the front cylinder injector somehow. And then I found it.

    The fuel/air sensor for the front injector was sticking out just a little bit more than the one for the rear cylinder injector. Now, whether that was something that I did when I removed the fuel lines, or whether there's an O-ring that's perished that's let it come out I don't know, but it has had the effect of making the ECU think that front cylinder is running lean, which made it richen up the mixture in the front cylinder. End result - popping and backfiring on over-run and off-throttle, and higher fuel consumption. Not to mention a wandering idle that I had to sit at 2000 rpm because I'd wound up the idle air mixture to compensate. Now, the idle is back to 1200rpm, the idle air mixture screws are wound back to where they were, and it's purring like a kitten again.

    To say I'm pleased would be an understatement.

    Now I'm going to have to find out if these fuel/air sensors are supposed to be a soft fit or if there's some kind of O-ring that I need to replace.
    And I to my motorcycle parked like the soul of the junkyard. Restored, a bicycle fleshed with power, and tore off. Up Highway 106 continually drunk on the wind in my mouth. Wringing the handlebar for speed, wild to be wreckage forever.

    - James Dickey, Cherrylog Road.

  8. #8
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    Interesting.


    So if you took it to a shop, presumably they plug in the computer and see if anything shows up as off - I wonder if this would or would it be experience or trial and error.

  9. #9
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    Quote Originally Posted by AllanB View Post
    Interesting.


    So if you took it to a shop, presumably they plug in the computer and see if anything shows up as off - I wonder if this would or would it be experience or trial and error.
    Well. the Aprilia does have diagnostics ability and there weren't any diagnostic problems showing. This is exactly what would have shown up if they plugged in the computer - they could possibly have seen that cylinder 1 was reading lean. Knowing my luck they would have replaced the vacuum lines and fuel/air sensors before advising me that they'd sorted the problem - $1000 please. Cha-ching.

    But maybe not. Perhaps I'm being too harsh. It must be my Scottish/Latvian Jew heritage... I always like to see if I can fix it myself before I throw it at the shop.

    No idea if this sensor is gonna pop out again though. Seems to be a bit of a loose fit, but I'm picking the vacuum holds it in ... if it's in there enough in the first place. Weird... but that's Italians for you.
    And I to my motorcycle parked like the soul of the junkyard. Restored, a bicycle fleshed with power, and tore off. Up Highway 106 continually drunk on the wind in my mouth. Wringing the handlebar for speed, wild to be wreckage forever.

    - James Dickey, Cherrylog Road.

  10. #10
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    Quote Originally Posted by riffer View Post
    Well. the Aprilia does have diagnostics ability and there weren't any diagnostic problems showing. This is exactly what would have shown up if they plugged in the computer - they could possibly have seen that cylinder 1 was reading lean. Knowing my luck they would have replaced the vacuum lines and fuel/air sensors before advising me that they'd sorted the problem - $1000 please. Cha-ching.

    But maybe not. Perhaps I'm being too harsh. It must be my Scottish/Latvian Jew heritage... I always like to see if I can fix it myself before I throw it at the shop.

    No idea if this sensor is gonna pop out again though. Seems to be a bit of a loose fit, but I'm picking the vacuum holds it in ... if it's in there enough in the first place. Weird... but that's Italians for you.
    Well done
    Now take the thing out, and enjoy it !
    RSV Mille: No madam, its an Aprilia, not a Harley. If it were a Harley, I would be pushing it !

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