VF1000 fuel issues

Discussion in '1st & 2nd Generation 1983-1989' started by cookies, Mar 31, 2021.

  1. cookies

    cookies New Member

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    Hey guys, new here and was looking to get some advice on my troubleshooting. I recently started working on a 84 VF1000 that has been my dads bike since the 90's. The bike was used regularly until 2010 and then started once every few months until 2019. Bike will turn over but not fire.

    Replaced the old battery.
    Syphoned gas from tank and replaced with new gas. (old gas looked to be fine when removed)

    I cannot hear the fuel pump priming once the key has been turned into the "on" position. I know I can test the wires coming into the fuel pump and there seems to be some relay or fuse that also goes bad. I just can't for the life of me find where to actually test on the bike with my meter.
    -Fuel Pump does not prime in the "On" position, ended up being a stuck fuel pump

    Update#1
    The bike will now idle and can rev. I notice that she sits at around 2,500-3,000 rpm once it has some heat in it. I checked the mixture screws and they are 3-3.5 turns out depending on the screw. She also likes to pop a bit from the exhaust when I get on the throttle. I'm thinking she is running rich because of the mixture screw. For the high idle I was initially thinking the idle was set high, but she jumps around in revs a bit which makes me think there is a vacuum leak.

    What is the factory setting for the mixture screws?
    Where is the idle adjustment on these bikes?
    -Found the idle adjustment between the carbs. Was having issues with throttle sticking before which was preventing the idle from dropping when I turned the knob.

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    Last edited: May 3, 2021
  2. Captain 80s

    Captain 80s Member

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    The pumps on the VF/VFRs do not "prime" when the key is turned on. Sometimes you'll get one click when you turn the key. They only pump when then the engine is being cranked or when it's running. The fuel pump relay is on the left side near the regulator / rectifier under the side cover. You can unplug the relay and jump 2 wires to bypass and see if the pump is working (Blue and Black??). I'm just going from memory, but you can try a couple combos til you find it. There's a turn signal relay in that area too, so be sure you've identified the right relay.

    The relays are know to fail. I wire in parallel toggle switches on all my bikes to prime the fuel system (like after winter storage) or to save my ass if the relay fails out on the road. There are many people that just permanently bypass it, but I like to keep it as long as I have my back up plan in place. It has saved me twice on two different bikes: Once in the middle of a floating bridge and once pretty far out in the country.

    Don't rule out the possibility the carbs need a proper cleaning. Even starting every now and then is often not enough to eliminate carbs fouling up.
     
  3. cookies

    cookies New Member

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    Didn't know that, at least jumping the relay seems easier than chasing wires.

    Yeah trying to rule everything out before I go for the carbs. Haven't worked on carbs a whole lot, a bit daunting especially when parts seem so hard to find.

    Will keep that in mind for the future lol
     
  4. Captain 80s

    Captain 80s Member

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    Parts you need to take care of the carbs are available. Suitable Viton o-rings can be sourced WAY cheaper than OEM. Reach out before you source any. I rebuild my V4 carbs for about $3 in rubber.

    The intake boots will be the biggest expense and I highly recommend replacing them if the carbs have to come out.
     
    Last edited: Apr 5, 2021
  5. squirrelman

    squirrelman Member

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    if you heaR THE PUMP TICKING alot WHEN YOU TURN ON THE KEY IT Suggests that the pump relay has ALREADY been hotwired. (blue to blue/black)
     
    Last edited: Mar 31, 2021
  6. cookies

    cookies New Member

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    So I ended up taking the fuel tank off, pulling the fuel pump and changing the fuel lines. The fuel pump was the culprit, whaled on it with a hammer for a while and it started right up after. Seems like the carbs are a bit gunked up as it will hold idle with about half choke but anything else it will die. Going to put some carb cleaner through it this week and hope she clears up, if not looks like I'm going to be pulling those carbs.

    I went through the clutch master cylinder and found that what ever fluid had been in there had turned to solid....fun. Cleaned it out then blew out the fluid in the line going to the bike. After refilling it and attempting to bleed it I cannot seem to build pressure, I can see the piston moving inside the master when I look in from the top but it won't build pressure. I'm thinking a seal or something has gone out.

    I have also been having issues with my front brake, where even after bleeding it the tire and lever will lock up after letting it sit for a few days. Bleeding it again will loosen them both back up. Not sure what it is as it doesn't seem to be an issue with air in the lines.
     
    Last edited: Apr 4, 2021
  7. squirrelman

    squirrelman Member

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    to get pressure in the clutch mc........try removing the slave cylinder and use a C-clamp to hold the piston fully retracted. you may need to remove the mc banjo bolt and bleed from there first.

    you know the carbs need work if it only idles with choke on, and cleaning chemicals seldom work, but you can try seafoam.

    make sure the front brake mc has an air space above the fluid, not too full.
     
    Last edited: Apr 5, 2021
  8. cookies

    cookies New Member

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    Updated Post
     
  9. straycat

    straycat New Member

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    I would only add a note here to say, do NOT spray the aerosol type carb cleaner into those carbs while they are still fully assembled. many carb cleaners will turn the rubber diaphragms into goo pretty quick if it gets into that top area under the round chrome cover.
     
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