Sputtered out bike

Discussion in 'Mechanics Garage' started by 1990 vfr 750, Apr 14, 2025.

  1. 1990 vfr 750

    1990 vfr 750 New Member

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    Hello all,
    The bike in question is a 1990 honda vfr 750 r
    Currently I am having some issues with my bike is don't know what it is happy to hear suggestions. So to start last week I was out for a ride and thankfully just before I got home my bike started to sputter and then died. It wouldn't start again so I started to walk It home. When I got home it started again which was weird so I took it for a test ride and it again sputtered out and died. It is important to note when my bike dies. It is always under load for example I true and accelerate a little above normal or when ever I start to go up a hill. Or when I go into second.

    My first attempt at fixing this was the fuel pump which I replaced and it is not the issue. I thought this was it forsure as it was already leaking.

    After I replaced the fuel pump it idled no problems I was even able to rev it. I was starting to ease the anxiety of having not being able to go out this early in the season.

    What are your thoughts ? I'm thinking it's not spark plugs as I am able to idle. Carb issue sounds strange as I cleaned it before winter and it was working well when I went for the few rides so far. Could be vacuum issues or maybe a leak somewhere else.
     


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  2. squirrelman

    squirrelman Member

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    trusting that you did the carbs properly ;) you might have missed tightening some carb mount clamps.
     


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  3. Terry Smith

    Terry Smith Member

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    Sure sounds like fuel flow to me.

    Is the tank vent open and allowing air back in as fuel comes out?
    Have you kinked a fuel hose from the pump to the carbs?
     


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  4. 1990 vfr 750

    1990 vfr 750 New Member

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    It could be one of the vacuum issue. I will test this and let you know for the kinked hose I dont think so cause I didn't move anything.
     


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  5. 1990 vfr 750

    1990 vfr 750 New Member

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    I am certain I cleaned it correctly I took everything apart cleaned it with carb cleaner and tooth brush and put it back together. Well. It could be a tightening of a carb mount I'll check those
     


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  6. Captain 80s

    Captain 80s Member

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    Jump the Fuel Cut Relay as a test too if everything else checks out. While they usually just fail, they can be intermittent when failing. I had one like that.

    Unplug the relay from the harness and make a jumper wire. Not exactly sure which 2 wires on the 1990 from memory, but on some bikes it is black and black/blue. The pump will operate normally without the relay when the harness side is jumped correctly.
     
    Last edited: Apr 16, 2025


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