5th Gen VFR bugging acceleration

Discussion in 'Mechanics Garage' started by Gerren Brook Hunter, Jul 5, 2021.

  1. Gerren Brook Hunter

    Gerren Brook Hunter New Member

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    Hey everyone, new here. Couldn't find anything like this on google so I figured I would try asking here.

    I am recently a proud owner of a 5th generation VFR (year 2000) and I've had my bike for about a month now. I recently took a trip through the mountains and came home to some very bad weather. I spent about 4-5 hours driving in the rain and me and my bike got absolutely drenched.

    Now when I try to run my bike, my acceleration is probably a 6th of what i use't to be. The bike struggles to get into gear and has no bottom end at all. She doesn't want to go past 6000rpm and struggles to go over 100km/h. Uh oh!

    I figured I flooded something and I tried checking my air filter. It seemed ok... the container and filter was a little wet and smelled a little bit like petro but it could just be that the gas tank covers the filter so I don't think that's it. I also took a look at all the sparkplugs and none of them were wet but could probably use replacing.

    I also tried unplugging the battery for a minute or two and replugging it back in to see if there was any error codes that would pop up. While the bike does a 'lamp check' on startup, all is good but the oil pressure light remains on. Now this light will stay on until my bike's engine turns on, then it will turn off. Definitely wasn't doing that before so that might be hint!

    If anyone here could help me out I would greatly appreciate it!
     
  2. GreginDenver

    GreginDenver New Member

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    I'm going to latch onto the part of your story where you said, "I recently took a trip through the mountains" and "very bad weather".

    Since your problems started with a combination of high altitude and bad weather (lots of rain) my bet is that one or both of your VFR's pressure sensors are messed up. The two pressure sensors are the MAP Sensor and the BARO Sensor. I'm betting one or maybe both of them has water in it (and the MAP Sensor has tubing connecting it to the Throttle Body Assembly so there's also the possibility of water in that tubing to consider).

    Trapped water could block the BARO Sensor from being able to "return" to a sea level pressure reading as you rode down out of the mountains. Trapped water could prevent the MAP Sensor from sensing the vacuum pull in the bike's Throttle Body (or maybe it would just reduce the MAP Sensor's normal sensitivity to Throttle Body pressure changes).

    That's my guess.
     
    Last edited: Jul 5, 2021
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  3. Gerren Brook Hunter

    Gerren Brook Hunter New Member

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    Hey, thank you for the response.

    For clarity, I didn't get rained on until I got out of the mountains. I did some googling about the BARO and MAP sensor... shouldn't my bike be throwing some F1 codes?

    Also, where are those sensors located? Is that something I can do, or should I take it to the shop?

    I really appreciate your help.

    Gerren
     
  4. GreginDenver

    GreginDenver New Member

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    The bike's ECM will "throw codes" if the sensor is dead or the voltage on the line is way out of range, but it won't throw a code if the sensor is just messed up somehow and reporting a value that's wrong for the actual condition.

    First thing you should do is download the electronic copy of the 1998-2001 Honda VFR800FI Service Manual. I can't remember if it's available here on VFRWorld.com but I'm pretty sure it's available on VFRDiscussion.com.

    Okay, I went to VFRDiscussion.com and found the Service Manual, it's in the "Downloads" section. Here's a link to it:

    https://www.vfrdiscussion.com/index...onda-vfr-service-manual-optimized-bookmarked/
     
    Last edited: Jul 7, 2021
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  5. GreginDenver

    GreginDenver New Member

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    Once you have the Service Manual in hand there's nothing you can't figure out about your VFR800. If you can read and follow instructions this Service Manual will explain the situation and walk you through just about any maintenance issue.
     
  6. Grum

    Grum New Member

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    "I also tried unplugging the battery for a minute or two and replugging it back in to see if there was any error codes that would pop up. While the bike does a 'lamp check' on startup, all is good but the oil pressure light remains on. Now this light will stay on until my bike's engine turns on, then it will turn off. Definitely wasn't doing that before so that might be hint! "

    - It's completely Normal for the Oil Pressure light to remain ON until the engine is running and oil pressure build up will then turn the light OFF.
    - Wonder if your Air Filter is saturated with water and restricting air flow, seeing you noticed a bit of water in the air filter housing. Remove your Air Filter and give it a very good going over with a hair dryer, see if this helps.
    - Make sure when checking for active EFI codes that your SideStand is Down.

    Good Luck
     
  7. raYzerman

    raYzerman Insider

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    Have you checked the chassis ground and the orange ground spider? Poor grounds can be an issue. A prevention clean might be in order anyway.
     
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