fuel, overheat or flooding issue??? No power loss then the engine dies.

Discussion in '1st & 2nd Generation 1983-1989' started by garageking700f2, Jul 19, 2014.

  1. garageking700f2

    garageking700f2 New Member

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    So I've been working on getting her road worthy and finally did last week. Took her around for about 5 minutes then went to fill it up. Wouldn't start... had to push her home. Thought it could be the 9 amp battery that was in it so i got a fresh new 12 and I thought we were good. Started great today, ran perfect for about 10-15 minutes until I goosed it a bit.... and she died. Parked in a nice ladies driveway because it wouldn't start and walked home. Came back 2 hours later and came right to life. What gives! I'm thinking fuel line. Is it normal to have this much air in the filter?? 20140719_182824.jpg
     
    Last edited: Jul 20, 2014
  2. RotaryRocketeer

    RotaryRocketeer New Member

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    The filter is prone to having that much air in it from time to time, you'll drive yourself crazy worrying about it. Not a big issue IMHO. Flow-tested the fuel pump or tried bypassing the relay yet? Next time it happens, open a float bowl drain and see if you have fuel in the carbs.
     
  3. garageking700f2

    garageking700f2 New Member

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    I'll have to try again this weekend. It just seemed very odd that it cut out in the middle of the road after riding for like 20 minutes. The pump is working, but could it just not be working well enough? I was looking into the fuel filter and even when I rev it a bit sitting still there is just a very slow drip coming out of the fuel line. Is that normal?
     
    Last edited: Jul 21, 2014
  4. RotaryRocketeer

    RotaryRocketeer New Member

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    Flow test procedures are in the manual. I think it's supposed to pump something like 27.1 fluid oz. per minute. Just pump it into a can for 15 seconds, measure, and multiply by 4.
     
  5. RotaryRocketeer

    RotaryRocketeer New Member

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    I would suspect the fuel pump relay. It's a pretty well-known fault with our bikes. It can be bypassed easily so that the pump will run whenever it needs to. Bypass it, take her for a ride and see what happens?
     
  6. Hermie0311

    Hermie0311 New Member

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    This happened to me last night! I've been doing some research on this because it won't start again after it is warmed up and been running for a while, last night was the first time it died on me while riding. I'm thinking it's a heat issue. Like I said, I've been doing some research, and I think the coils are getting hot and building up resistance and therefore not firing.
    It left me stranded last night so I'm going to go get it tonight, ride it home, and do some testing on it. I'll let you know what I find/think I find.
     
  7. RotaryRocketeer

    RotaryRocketeer New Member

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    I posted about this same thing as well last week. I bypassed the relay (again, I already had a wire made up in my backpack) and put 20 trouble-free moderate traffic city miles on it before I had to run to a prior engagement. I'm hoping it's fixed. Then again, I tested my coils a while back due to another since solved problem, so I'm confident that they're good. Best of luck, and post your results!
     
  8. garageking700f2

    garageking700f2 New Member

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    PERFECT! So I'm not the only one with this PITA problem. To Bypass the pump relay should I just hook it right to the battery? I'll test the flow before I do that, hopefully tonight. Thanks for the input.
     
  9. Hermie0311

    Hermie0311 New Member

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    To test the fuel pump all you need to do is unplug the relay and take a piece of wire and jump the two outside wires I believe (there are 3 on the plug). I have put a new fuel pump on mine since I've had the bike so I'm fairly confident it's not that, at least for me.
     
  10. RotaryRocketeer

    RotaryRocketeer New Member

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    On the '86 there should only be two wires, one is black and the other black/blue. Just cut a short length of wire (I put some prongs on the ends to make it easy to plug in) and connect the two sides of the plug. This should supply constant power.

    Edit: The plug I'm referencing is the one that plugs into the bottom of the relay next to the yellow/green wire.
     
    Last edited: Jul 22, 2014
  11. Dukiedook

    Dukiedook New Member

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    Chuck the fuel pump relay as stated above and jump the leads (The HFM tells you how to do this).
    If you wreck you are in trouble anyway, might as well go out in a flaming ball of fire.
     
  12. NormK

    NormK New Member

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    I'm having a similar problem since I fitted an aftermarket Fawcet style pump which requires a filter fitted before the pump and as room in there is very restricted I fitted the filter horizontally in behind the rectifier and the fact it is horizontal is the problem with air getting trapped in the filter. Today I'm going to see if I can fit it vertically, take the hose down and come up under the pump and see how that goes
     
  13. garageking700f2

    garageking700f2 New Member

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    Well the pump works great. Maybe too good? 16 oz in 15 Seconds...
     

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    Last edited: Jul 23, 2014
  14. Hermie0311

    Hermie0311 New Member

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    I did a little testing on mine last night after I got it back home. My theory was the coils, which I still think there is a problem with because they were reading with a resistance of 4.2 ohms instead of 2.8 like they should be (hot or cold). That seems pretty high to me, so maybe it's a combination.
    But after doing some consulting with a friend, they only thing I've done to the engine since the last time it ran good was I changed the lower radiator. I'm thinking maybe there is a lot of air trapped in the system? After I got it home the bike was super hot but both radiators were pretty cold. I checked the thermostat and it seemed ok, although I'm probably going to replace it since it's cheap anyway. Thoughts?
     
  15. squirrelman

    squirrelman Member

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    Items that fail randomly due to heat are almost always electrical. I had a problem with an '86 700 that would suddenly run rough every time i'd started (started OK) then ridden 15 or 20 minutes. A failing pulse generator coil was the only problem !!
     
  16. garageking700f2

    garageking700f2 New Member

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    That's got to be it then, easy fix?
     
  17. Dukiedook

    Dukiedook New Member

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    Not horrible as long as you can source a new coil and those are NLA new.
     
  18. MPH Racing

    MPH Racing New Member

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    I have almost the same problem but with mine it's the carbs flooding when it gets to operating temp and killing the engine. I shut off all the idle mixture screws and the bike still runs till it gets warm then I can hear the fuel flowing past the float and killing the bike. Until the bike warms up the thing runs great and then dies. After 30min to an hour sitting it fires right up again till it gets warm again. I will be taking the carbs in for a full rebuild and service and see if it fix's the problem.
     
  19. Hermie0311

    Hermie0311 New Member

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    So I think Squirrelman is right, at least with me bike. I checked the resistance on the pulse coils and the one with yellow wires was reading fine, but the one with blue wires was reading something like 1600 ohms. They should be 480 ohms according to the shop manual. I'll know for sure when I can find some replacements and install them.
     
  20. Hermie0311

    Hermie0311 New Member

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    Does anyone know if the pulse coils from a vf500f or maybe a sabre/magna of the same year as my bike will work on the vf750f interceptor?
     
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