VFR Dies When Warm

Discussion in '3rd & 4th Generation 1990-1997' started by Durus, Jun 22, 2021.

  1. Durus

    Durus New Member

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    Guys, help me out here. I love my baby and pretty soon I'll be taking her across the country. She's been treating me right for a long time but now, as it's warmed up here in Louisiana, she's started dying when the temp gauge gets around midway. Starts up cold with choke and runs fantastic up until this point. Then lugs and dies as if it's got no spark or no fuel. What's weird is that it will not start again UNLESS I put the choke on. Then she starts right up. Will run on the choke until I lower it to about 2000 rpm then she lugs and dies. What gives? This almost sound like the bike is leaning out when warm. But that doesn't happen right? If anything shouldn't it get richer when warm? I pulled my plugs and they look okay to me. Not even wet or smelling of fuel. I also checked the secondary windings on my ignition coils and I checked the pulse generator and both read good on resistance. What's happening?
     
  2. Durus

    Durus New Member

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    All the plugs look something like this.
     

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  3. Diving Pete

    Diving Pete Member

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    When was it last serviced?
     
  4. Captain 80s

    Captain 80s Member

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    Fuel pump starting to go and gets ugly when everything is hot? Also you might consider temporarily bypassing the fuel cut relay and make sure it's not acting weird when hot. They usually just fail, but you never know.

    Pop the gas cap next time and make sure it's venting properly too.

    Frustrating I'm sure.
     
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  5. Durus

    Durus New Member

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    I do all the service myself. Is there something specific you're talking about? The carb?
     
  6. Durus

    Durus New Member

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    So I checked the fuel pump points not that long ago and they had plenty of life left on them. Is there another potential point of failure inside it? Also wouldn't it not work regardless of the choke? The fact that it runs on choke is what leads me to believe it isn't related to fuel delivery. I measured resistance at the cut relay and it was fine. Also no signs of melting. Clean too.

    If it's a problem with tank venting wouldn't I hear a release of pressure when I opened the tank? I thought this could be the issue as well so I tried opening it and it neither made an audible sound nor did it fix the problem. Although, there are no hoses leaving the tank other than the fuel hose and I've always wondered how it should really be set up from the factory.
     
  7. Captain 80s

    Captain 80s Member

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    I was throwing it out there that perhaps the diaphragm in the pump is failing, not the points. The fact that it starts on "choke", which is actually an enrichening circuit, is odd. But I know sometimes when I'm running out of fuel in the driveway (and haven't realized it yet), the bike will then start on "choke" for a little while.

    I don't know... just throwing shit out there.

    One more thing, resistance tests are not definitive. It could still be the pulsar coils, the relay, an ignition coil, etc. I would still bypass the relay as a sanity check, as it's easy and you can then eliminate it before spending money elsewhere.

    Good luck!!!
     
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  8. Durus

    Durus New Member

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    Thanks for your help Captain! I'll bypass the relay and also monitor my pump when recreating the problem and see what happens.
     
  9. VFRVogt

    VFRVogt New Member

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    Hmm…I’m sort of experiencing something similar except mine will start and run for a while normally-but after a warm up and some riding miles, it starts to die off unless I put the choke on about a 1/4. I thought: Fuel Pump. Ordered a replacement from highflowfuel.com but still starts to cut off unless choked.
    BTW the fuel pump is a perfect match. $75
     
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