Loss of power

Discussion in 'Mechanics Garage' started by mikeplayer, May 25, 2021.

  1. mikeplayer

    mikeplayer New Member

    Country:
    United States
    Joined:
    Jul 11, 2015
    Messages:
    2
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Ottawa Ontario
    Map
    • [​IMG] [​IMG] [​IMG] [​IMG] [​IMG]
    • Hey gang. I have a 2002 vfr800 interceptor with 55000kms on it, two brothers exhaust, power comander and k&n filter. Riding today at highway speed, suddenly lost power. Had to trailer home. The bike will start and runish with significant throttle but is clearly unhappy and won't stay running. It sounds like it may be running on 1 or 2 cylinders. The valves have not been adjusted. Any ideas on the best place to start? Given the sudden and extreme loss of operability, I'm thinking cam chain. I've already disconnected the power commander to no effect to eliminate that possibility. Was thinking plugs as a simple fix but it seems unlikely to be that sudden and drastic. Had no fault indication on the dashboard.
     
  2. Captain 80s

    Captain 80s Member

    Country:
    United States
    Joined:
    Apr 25, 2009
    Messages:
    5,824
    Likes Received:
    2,353
    Trophy Points:
    158
    I'd personally start with checking for spark. Also due to the number of times I've read about it, the early VTEC VFRs seem to be very susceptible to corrosion in some of the connectors. Disconnect, clean, inspect the major players to start with.

    I'm sure a few more peeps will be along. I've worked on one once tracking down a no-start situation. Stupid Fucking Spaceship. That problem is not yours, turned out to be a wrong ignition switch installed by PO after being stolen.
     
  3. Simon Edwards

    Simon Edwards New Member

    Country:
    United Kingdom
    Joined:
    Mar 16, 2021
    Messages:
    51
    Likes Received:
    18
    Trophy Points:
    8
    Location:
    Berkshire
    Map
    I'm more of a carb' guy, and there are plenty of others on the forums with far more experience of these, but I'll make a few suggestions if I may?

    Given the sudden loss at speed it appeaers as though something let go under stress.

    If this was a car I'd be looking straight at the MAF sensor(s) for this symptom. Preferably by reading the fault codes from the ECU to confirm it. But on the VFR the MAF appears to be driven by a complex collection of pipes instead of the direct air filter to throttle-body flow you'd find driving it in a car installation. Like I said I'm not used to the VFR setup, but there are a lot more hoses and joints that could throw the sensor out on a VFR.

    As far as I can tell the MAF is F-21 (P/N 37830MCF003) here https://www.cmsnl.com/honda-vfr800-2002-2-england_model5703/partslist/E__1701.html#.YKz7yqHTUUQ

    Which is also item 14 here: https://www.cmsnl.com/honda-vfr800-2002-2-england_model5703/partslist/F__2100.html#.YK1nLqHTUUQ

    I guess that if any one of those hoses were split, or a joint were leaking it'd show up like your symptoms. Or of course the MAF itself or its wiring could have failed.

    If I were betting, I'd be looking very carefully at those 19 year-old hoses and their unions for any hardened rubber and leaks. A smoke tester inserted into the hose where it joins the MAF would show you this without needing to strip the bike down to take a look at each one.

    After that, assuming I am wrong, I'd go with a back to basics check:

    Is it getting enough fuel? So...
    Check for a blocked or otherwise collapsed fuel filter?
    Fuel pump failure. Note: Although rare. just because its buzzing and sounds like its running doesn't mean it is capable of supplying at full capacity.
    Blocked injectors or feeds. Leaky feeds.

    Is it getting the right amount of fuel?
    Failed fuel pressure regulator
    Failure in any of the vacuum hoses that control that regulator.
    Failed ECU causing injector chaos.

    Is it getting enough Air?
    Air filter collapse or blockage?

    Can it ignite the mixture?
    Its unlikely, but I suppose it could have lost one or two coils, or the timing generator could have failed, so check for sparks at all plugs.

    After that I'm out of ideas.
     
  4. Diving Pete

    Diving Pete Member

    Country:
    United Kingdom
    Joined:
    Mar 25, 2016
    Messages:
    1,969
    Likes Received:
    548
    Trophy Points:
    143
    Location:
    London
    Map
    Check the earths on the left front mount. If only on 2 it could be that.
    Whats your voltage on the battery & output from stator..
     
  5. Diving Pete

    Diving Pete Member

    Country:
    United Kingdom
    Joined:
    Mar 25, 2016
    Messages:
    1,969
    Likes Received:
    548
    Trophy Points:
    143
    Location:
    London
    Map
    A coil pack failing will cause this.


    This will not matter - lol

    Earths

    Nope

    good idea, just unlikely

    Nope not plugs.
     
  6. Alan1234

    Alan1234 New Member

    Country:
    United States
    Joined:
    May 21, 2021
    Messages:
    5
    Likes Received:
    0
    Trophy Points:
    1
    Does it run ok when the bike has cooled down? I had almost the exact issue on my 85 VF 500. Once it cooled down it ran great until it warmed up again. Turned out that the screws holding one of the coils to its bracket had come out so the coil was just dangling almost on top of the hot valve cover. I guess the ground on the coil is heat ground and not a regular electrical ground. For me the coil was working properly but was just overheating
     
Related Topics

Share This Page