Results 1 to 28 of 28
  1. #1
    Senior Member
    Join Date
    Aug 2006
    Location
    Manassas, VA
    Country
    My Ride
    1987 VFR 700
    Posts
    109
    Thanks
    0
    Thanked 12 Times in 7 Posts

    87 VFR 700 Fuel Pump...not pumping.

    Before I go off half cocked and buy a new fuel pump, I'd like to make sure it's hosed.

    I jumped the black/black-blue wire to test it. I can hear the motor going, but nothing is coming out. Lines are hooked up correctly, I see gas in the fuel filter on the inlet side, no pinches in the lines etc, etc. Anything else I can try, or is it time for a new one?

    87 VFR 700 F2 (restored)
    02 FZ1
    03 KLR 650
    93 KDX 200
    89 YZ 250 (restored)
    84 CR 250 (restoration doubtful)

  2. #2
    Senior Member Dukiedook's Avatar
    Join Date
    Oct 2009
    Location
    Kansas City, USA
    Country
    My Ride
    1973 K3 CB750 (2) 1986 VFR750F
    Posts
    979
    Thanks
    1
    Thanked 42 Times in 42 Posts
    I don't think these are rebuildable, probably need to start looking for a replacement.
    Anyone know of a newer/more reliable substitute fuel pump you can use in this situation?

  3. #3
    Uber Guru Rollin_Again's Avatar
    Join Date
    May 2008
    Location
    Duluth, GA
    Country
    My Ride
    Going...Going...Gone....(2007 VFR800 RWB (SOLD) (1993 VFR750F - SOLD)
    Posts
    2,313
    Thanks
    46
    Thanked 294 Times in 223 Posts
    You should be able to bypass the fuel pump altogether and use a gravity fed system. The only modification you may need to do is alter the petcock so that it doesn't require vacuum to be actuated. Jamie Daugherty can give you more details on how to do it.

    Regards,
    Rollin

  4. #4
    Senior Member
    Join Date
    Aug 2006
    Location
    Manassas, VA
    Country
    My Ride
    1987 VFR 700
    Posts
    109
    Thanks
    0
    Thanked 12 Times in 7 Posts
    I know I can go with a gravity feed setup, but...I'm just planning to run it stock with the fuel pump. Are there alternatives to the oem replacement at $150?
    87 VFR 700 F2 (restored)
    02 FZ1
    03 KLR 650
    93 KDX 200
    89 YZ 250 (restored)
    84 CR 250 (restoration doubtful)

  5. #5
    Administrator

    tinkerinWstuff's Avatar
    Join Date
    Oct 2009
    Location
    Colorado Front Range
    Country
    My Ride
    '85 VF500f(sold) / '03 Honda Shadow(sold)/ '90VFR750(sold) / '98VFR800 / '99 DR650SE
    Posts
    7,545
    Thanks
    407
    Thanked 680 Times in 553 Posts
    Blog Entries
    2
    I'm not sure that gravity feed was recommended for the larger motors, only the 500?

    I'd recommend that you make sure it isn't a petcock problem. put the pickup line for the pump in a small fuel can and see if she'll pump.
    5th Gen Resurrection - Rebirth and re-invention of a wrecked 5th Gen

    3rd Gen Resurrection - Craigslist project bike

    Dumped the California Cams - swapped 49 states cams into a Cali' motor

  6. #6
    Uber Guru

    TOE CUTTER's Avatar
    Join Date
    Nov 2008
    Location
    Sacramento
    Country
    My Ride
    2007 RWB SUPERCHARGED / 1986 750 SSA
    Posts
    6,483
    Thanks
    210
    Thanked 704 Times in 559 Posts
    A fuel pump is a must have item for gen 2 , it will only gravity feed until the fuel is level with the petcock. About half a tank and does a rather poor job at that. Have you tried to blow throught the pump to see if the valve is stuck or stuck open?
    I am nuttier than a squirrel turd "Nancy Pelosi"

    My theme music.
    http://www.youtube.com/watch?v=_r-M9gipm9s

    Only a motorcycle rider knows why a dog sticks his head out a car window.

  7. #7
    Senior Member
    Join Date
    Aug 2006
    Location
    Manassas, VA
    Country
    My Ride
    1987 VFR 700
    Posts
    109
    Thanks
    0
    Thanked 12 Times in 7 Posts
    I'm getting fuel all the way through. Gas comes out of the petcock, goes through the line through the filter. Free flowing all the way to the inlet side of the fuel pump using reserve, on, and turns off when I throw it to off. Now I'm just getting a click every time I jump it. It's not even running as it had before. Toasted fuel pump...
    87 VFR 700 F2 (restored)
    02 FZ1
    03 KLR 650
    93 KDX 200
    89 YZ 250 (restored)
    84 CR 250 (restoration doubtful)

  8. #8
    Uber Guru squirrelman's Avatar
    Join Date
    Jul 2006
    Location
    Barf-a-load, ny
    Country
    My Ride
    '86 VFR 700F X3/ '97 VFR 750F/ '89 NT 650 HAWK/ '86 Yamaha Radian X2/ '66 Yamaha YL-1/ '88 VTR 250 / '90 VTR 250/ '73 CB 125
    Posts
    6,969
    Thanks
    286
    Thanked 591 Times in 534 Posts
    IF it clicks, it's alive, but you could have a bad diaphram or debris in either one of the two one-way valves.

    If fuel is going in, try running output side into a can and check volume of flow.

    Pump does NOT run continuously as it senses pressure and turns itself off as long as fuel pressure is built up in outlet side.



    " Goin' to Hell in a bucket, but at least I'm enjoyin' the ride. "


    FRACKING: kiss your aquifer good-bye !!

  9. #9
    Junior Member
    Join Date
    Dec 2009
    Country
    Posts
    8
    Thanks
    0
    Thanked 0 Times in 0 Posts
    i had the fuel pump diaphram go bad in my 86 and i picked up a low psi (2-5psi) universal auto fuel pump from auto zone and direct wired it to the hot line going into the fuel pump relay and a negative to the battery. had to bypass the relay because the relay wasnt allowing a full flow of current into the pump which it needed to work. as long as you turn your bike off when your not running it,no probs, as the relay only regulates the current to the oem pump to keep it from flooding the carbs.works like a dream, and it only cost me 35 bucks and 15 min work.if you have to test electrical systems tho i recomend you disconnect the pump's power or you will overflow the carbs.

  10. #10
    Uber Guru squirrelman's Avatar
    Join Date
    Jul 2006
    Location
    Barf-a-load, ny
    Country
    My Ride
    '86 VFR 700F X3/ '97 VFR 750F/ '89 NT 650 HAWK/ '86 Yamaha Radian X2/ '66 Yamaha YL-1/ '88 VTR 250 / '90 VTR 250/ '73 CB 125
    Posts
    6,969
    Thanks
    286
    Thanked 591 Times in 534 Posts
    Glad your generic pump works, but you have a few misunderstandings of the system. Have u read the service manual ??

    OEM pump will never flood good carbs if carbs are good.



    " Goin' to Hell in a bucket, but at least I'm enjoyin' the ride. "


    FRACKING: kiss your aquifer good-bye !!

  11. #11
    Administrator

    tinkerinWstuff's Avatar
    Join Date
    Oct 2009
    Location
    Colorado Front Range
    Country
    My Ride
    '85 VF500f(sold) / '03 Honda Shadow(sold)/ '90VFR750(sold) / '98VFR800 / '99 DR650SE
    Posts
    7,545
    Thanks
    407
    Thanked 680 Times in 553 Posts
    Blog Entries
    2
    Quote Originally Posted by squirrelman View Post
    OEM pump will never flood good carbs if carbs are good.
    +1 Properly functioning needle/seat and floats. A stock pump that doesn't generate too much pressure will "dead-head" when the needle/seat close.
    5th Gen Resurrection - Rebirth and re-invention of a wrecked 5th Gen

    3rd Gen Resurrection - Craigslist project bike

    Dumped the California Cams - swapped 49 states cams into a Cali' motor

  12. #12
    Junior Member
    Join Date
    Dec 2009
    Country
    Posts
    8
    Thanks
    0
    Thanked 0 Times in 0 Posts
    with an oem pump it shouldnt overflow unless the carbs are dirty i agree. but i was talking about if he replaces the oem with the generic. the generic is a few pounds of pressure over the oem rating, and will flood the carbs if the bike is powered without starting the engine.

  13. #13
    Junior Member
    Join Date
    Dec 2009
    Country
    Posts
    8
    Thanks
    0
    Thanked 0 Times in 0 Posts
    from what i understood is that the relay supplies power to the pump only when the ignition is firing, to prevent flooding in case of mechanical probs so there isnt a fire. but only supplies power when engine revs are at a determined speed. i may be wrong but i dont know of any other reason to regulate power to the pump to run only when engine is firing other than a saftey measure. the pumps will work just fine without a relay, but the relay is there to prevent flooding in case of malfunction somewhere.

  14. #14
    Uber Guru squirrelman's Avatar
    Join Date
    Jul 2006
    Location
    Barf-a-load, ny
    Country
    My Ride
    '86 VFR 700F X3/ '97 VFR 750F/ '89 NT 650 HAWK/ '86 Yamaha Radian X2/ '66 Yamaha YL-1/ '88 VTR 250 / '90 VTR 250/ '73 CB 125
    Posts
    6,969
    Thanks
    286
    Thanked 591 Times in 534 Posts
    Quote Originally Posted by yllibllik View Post
    from what i understood only supplies power when engine revs are at a determined speed.
    Seems you might not understand.....power to pump whenever engine is turning.



    " Goin' to Hell in a bucket, but at least I'm enjoyin' the ride. "


    FRACKING: kiss your aquifer good-bye !!

  15. #15
    Junior Member
    Join Date
    Dec 2009
    Country
    Posts
    8
    Thanks
    0
    Thanked 0 Times in 0 Posts
    im pretty sure that is what i just said. my english may not be perfect but im sure that i said the relay only supplies power to the pump when the engine is running. i will repeat. the relay regulates power to the pump when the engine is running.r.i may be wrong but i dont know of any other reason to regulate power to the pump to run only when engine is firing, other than a saftey measure. the pumps will work just fine without a relay, but the relay is there to prevent flooding in case of malfunction somewhere.like an accident.seems i didnt explain myself well. i was only saying that he does not need the relay, because its only a saftey measure, that is not necessary to function. it is there to prevent fuel overflow in case of malfunction.if there is malfuntion the oem pump can indeed flood the bike and is dangerous so there is a relay to protect from overflow. if the carbs are empty than the pump will fire once when the ignition is pressed, but the pump will not run because engine wont spin fast. it has to spin at a certain speed.that is why you have to jump the oem pump when the carbs are empty its because of the relay. if all it took was a turning engine you could just hold down the ignition for a few seconds at a time until it filled.this is why it is called a fuel cut relay.it cuts fuel supply in case of mechanical problems. i dont know one wrong thing i said, but maybe that i didnt make myself more understandable.im sure i didnt missunderstand.i dont remember saying that the oem pump would flood a working system, only that the purpose of the relay was to protect against flooding and fuel overflow, which is true. and that the relay only powers the pump when the engine is running, which is also true.and that attaching a generic impeller pump with the psi rating i did and bypassing the relay you will flood the bike if it is not powered down, which is true.
    Last edited by yllibllik; 03-31-2010 at 12:43 AM.

  16. #16
    Senior Member
    Join Date
    Aug 2006
    Location
    Manassas, VA
    Country
    My Ride
    1987 VFR 700
    Posts
    109
    Thanks
    0
    Thanked 12 Times in 7 Posts
    Quote Originally Posted by squirrelman View Post
    IF it clicks, it's alive, but you could have a bad diaphram or debris in either one of the two one-way valves.

    If fuel is going in, try running output side into a can and check volume of flow.

    Pump does NOT run continuously as it senses pressure and turns itself off as long as fuel pressure is built up in outlet side.
    Back in the fall when I was having fuel issues, I was jumping it to verify that it was working, with no line connected to the carbs. It pumped gas into my jar every time. I would expect to see the same results this time. I did try blowing very low air pressure through the fuel pump, it didn't help.

    The entire thing was gone through last Fall. Carbs removed and cleaned etc. New petcock was installed, I also had some other issues and had to replace the fuel relay (new OEM unit).
    I'm probably just going to install a new OEM fuel pump if need be. My past experiences with jerry rigging things like this typically cost me more $ in the long run, so...oem seems to be the way I'm leaning.
    87 VFR 700 F2 (restored)
    02 FZ1
    03 KLR 650
    93 KDX 200
    89 YZ 250 (restored)
    84 CR 250 (restoration doubtful)

  17. #17
    Uber Guru squirrelman's Avatar
    Join Date
    Jul 2006
    Location
    Barf-a-load, ny
    Country
    My Ride
    '86 VFR 700F X3/ '97 VFR 750F/ '89 NT 650 HAWK/ '86 Yamaha Radian X2/ '66 Yamaha YL-1/ '88 VTR 250 / '90 VTR 250/ '73 CB 125
    Posts
    6,969
    Thanks
    286
    Thanked 591 Times in 534 Posts
    Quote Originally Posted by yllibllik View Post
    im pretty sure that is what i just said. my english may not be perfect but im sure that i said the relay only supplies power to the pump when the engine is running. i will repeat. the relay regulates power to the pump when the engine is running.r.i may be wrong but i dont know of any other reason to regulate power to the pump to run only when engine is firing, other than a saftey measure. the pumps will work just fine without a relay, but the relay is there to prevent flooding in case of malfunction somewhere.like an accident.seems i didnt explain myself well. i was only saying that he does not need the relay, because its only a saftey measure, that is not necessary to function. it is there to prevent fuel overflow in case of malfunction.if there is malfuntion the oem pump can indeed flood the bike and is dangerous so there is a relay to protect from overflow. if the carbs are empty than the pump will fire once when the ignition is pressed, but the pump will not run because engine wont spin fast. it has to spin at a certain speed.that is why you have to jump the oem pump when the carbs are empty its because of the relay. if all it took was a turning engine you could just hold down the ignition for a few seconds at a time until it filled.this is why it is called a fuel cut relay.it cuts fuel supply in case of mechanical problems. i dont know one wrong thing i said, but maybe that i didnt make myself more understandable.im sure i didnt missunderstand.i dont remember saying that the oem pump would flood a working system, only that the purpose of the relay was to protect against flooding and fuel overflow, which is true. and that the relay only powers the pump when the engine is running, which is also true.and that attaching a generic impeller pump with the psi rating i did and bypassing the relay you will flood the bike if it is not powered down, which is true.
    <<<<>>>>

    OK. man....you do understand, but i was referring to this statement :

    "........ but only supplies power when engine revs are at a determined speed. i may be wrong....."



    " Goin' to Hell in a bucket, but at least I'm enjoyin' the ride. "


    FRACKING: kiss your aquifer good-bye !!

  18. #18
    Senior Member captb's Avatar
    Join Date
    Jul 2009
    Location
    A Van down by the river Arizona
    Country
    My Ride
    1987 VFR 700 1998 CBR1100XX DRZ400E 2006 GS500F
    Posts
    622
    Thanks
    6
    Thanked 52 Times in 45 Posts
    VFR700.COM

  19. #19
    Junior Member dbmcd's Avatar
    Join Date
    Jul 2012
    Location
    Los Angeles, CA
    Country
    My Ride
    1984 VF1000F...1986 VFR700F
    Posts
    1
    Thanks
    1
    Thanked 0 Times in 0 Posts
    Quote Originally Posted by squirrelman View Post
    <<<<>>>>

    OK. man....you do understand, but i was referring to this statement :

    "........ but only supplies power when engine revs are at a determined speed. i may be wrong....."
    Why don't you tell him what he doesn't understand...YSS. You're not much help.

    Sent from my SM-G900P using Tapatalk

  20. #20
    Uber Guru squirrelman's Avatar
    Join Date
    Jul 2006
    Location
    Barf-a-load, ny
    Country
    My Ride
    '86 VFR 700F X3/ '97 VFR 750F/ '89 NT 650 HAWK/ '86 Yamaha Radian X2/ '66 Yamaha YL-1/ '88 VTR 250 / '90 VTR 250/ '73 CB 125
    Posts
    6,969
    Thanks
    286
    Thanked 591 Times in 534 Posts
    Quote Originally Posted by dbmcd View Post
    Why don't you tell him what he doesn't understand...YSS. You're not much help.
    His first post and he's already kikkin my ass !!


    Pump only supplies fuel when it senses lowering level in float bowls, not any predetermined engine speed !



    " Goin' to Hell in a bucket, but at least I'm enjoyin' the ride. "


    FRACKING: kiss your aquifer good-bye !!

  21. #21
    Senior Member JasonWW's Avatar
    Join Date
    Apr 2012
    Location
    Hou. TX
    Country
    My Ride
    86 VFR700F2 Pearl White
    Posts
    631
    Thanks
    3
    Thanked 31 Times in 31 Posts
    I believe the safety relay provides low voltage at low rpm and higher voltage at higher rpms. It provides zero voltage at zero rpm. The 86 model has the tachometer wire go through the safety relay while later models used a wire from one of the coils to go to the safety relay.

    This is designed to shut the fuel pump off in case of a crash. If the running bike falls over the carbs will flood out the engine shutting it off, but the key will still be on. So if the safety relay loses its pulses, it will not let voltage pass.

    I think the factory pump is rated at 1 psi or there about. As the carbs fill, the floats shut off supply and fuel pressure builds up to 1 psi. The pump will stop due to pressure build up. Then as the fuel levels in the carbs start to drop, the floats open the needles and fuel line pressure is removed. The pump will click and start pumping fuel again.

    I hope this helps.

    To the original poster, did you check the contacts? That's the rebuildable part of the pump. If they are okay and working, yet it's not flowing and the inlets and outlets are not mixed up, then it's probably the diaphragm or internal pump part not working. Also make sure the plunger is moving up and down as the pump clicks.

    I remember some oem type pumps for a different model honda on ebay costing about $30-$35 dollars that was identical, but had straight fittings instead of 90 curved fittings. These pumps would work fine if you attached rubber 90 boots onto the ends.
    Last edited by JasonWW; 12-15-2016 at 10:41 PM.
    Front end swap from 1990 Kawasaki ZX7 sportbike, taller police handlebars and Daugherty revalved rear shock. 97 CBR1100XX brake and clutch master cylinders. 98 VFR800 Euro switches. Euro turn signals. Yoshimura 4-1 exhaust. Hayabusa adjustable shifter. Universal gear indicator. Custom chain oiler. Koso EX-02S speedo. Working on slightly extended swing arm with Kawi rear wheel/170 tire.

  22. The Following User Says Thank You to JasonWW For This Useful Post:

    marcuch (01-06-2017)

  23. #22
    Uber Guru squirrelman's Avatar
    Join Date
    Jul 2006
    Location
    Barf-a-load, ny
    Country
    My Ride
    '86 VFR 700F X3/ '97 VFR 750F/ '89 NT 650 HAWK/ '86 Yamaha Radian X2/ '66 Yamaha YL-1/ '88 VTR 250 / '90 VTR 250/ '73 CB 125
    Posts
    6,969
    Thanks
    286
    Thanked 591 Times in 534 Posts
    oem pump is 3 PSI.



    " Goin' to Hell in a bucket, but at least I'm enjoyin' the ride. "


    FRACKING: kiss your aquifer good-bye !!

  24. #23
    Senior Member JasonWW's Avatar
    Join Date
    Apr 2012
    Location
    Hou. TX
    Country
    My Ride
    86 VFR700F2 Pearl White
    Posts
    631
    Thanks
    3
    Thanked 31 Times in 31 Posts
    Quote Originally Posted by squirrelman View Post
    oem pump is 3 PSI.
    That's higher than the 1 psi I was thinking, but I'll defer to you.

    The replacement fuel pump I was thinking of was for the cbr600. They are easy to find on ebay and run about $17. They are rated for 1-2 psi.
    Front end swap from 1990 Kawasaki ZX7 sportbike, taller police handlebars and Daugherty revalved rear shock. 97 CBR1100XX brake and clutch master cylinders. 98 VFR800 Euro switches. Euro turn signals. Yoshimura 4-1 exhaust. Hayabusa adjustable shifter. Universal gear indicator. Custom chain oiler. Koso EX-02S speedo. Working on slightly extended swing arm with Kawi rear wheel/170 tire.

  25. #24
    Junior Member
    Join Date
    Aug 2006
    Posts
    7
    Thanks
    1
    Thanked 0 Times in 0 Posts
    Quote Originally Posted by JasonWW View Post
    I believe the safety relay provides low voltage at low rpm and higher voltage at higher rpms. It provides zero voltage at zero rpm. The 86 model has the tachometer wire go through the safety relay while later models used a wire from one of the coils to go to the safety relay.
    I'm intrigued by your statement.
    I've been hunting running issues with my 87 VF1000 FF that I think is a dying 2-4 pulse generator coil. This is the one that sends the signal to the fuel pump.

    However, in troubleshooting this, I have found that the fuel cut-off relay, at idle RPM, only supplies 8-9v to the fuel pump. I cannot see how this is possible, as the relay appears to be more of an electrically activated switch than a relay, so there is no reason why voltage would drop from 12+ to barely 9 in passing through it. However, if what you are saying here is correct, then the at higher RPM, more voltage flows, then that would make sense.

    I tried two different FCoRs, one from a later CBR600F2, and both do the same thing, at idle RPM, they both supply between 8 and 9V to the pump.

    How is this achieved? A mate who is better at electrickery than I am, says the wiring diagram shows a device of some sort on the line between the FCoR and the pump that he says might be responsible for the voltage drop. However, on stripping back the loom, there is a single white wire completing that circuit, and there is no apparent device in it, but the resistance of this short run (no more than 100mm) is 4 Ohms, which seems high, but seems consistent with the ‘something in there’ theory.

    I've managed to get a spare old pulse generator coil assembly and fit it, I'll be firing it up tonight (fingers crossed), but I’m just intrigued to know what the story is with the fuel pump and its apparent voltage issues.

    Cheers,

    A

  26. #25
    Senior Member JasonWW's Avatar
    Join Date
    Apr 2012
    Location
    Hou. TX
    Country
    My Ride
    86 VFR700F2 Pearl White
    Posts
    631
    Thanks
    3
    Thanked 31 Times in 31 Posts
    Quote Originally Posted by Ascalon View Post
    I'm intrigued by your statement.
    I've been hunting running issues with my 87 VF1000 FF that I think is a dying 2-4 pulse generator coil. This is the one that sends the signal to the fuel pump.

    However, in troubleshooting this, I have found that the fuel cut-off relay, at idle RPM, only supplies 8-9v to the fuel pump. I cannot see how this is possible, as the relay appears to be more of an electrically activated switch than a relay, so there is no reason why voltage would drop from 12+ to barely 9 in passing through it. However, if what you are saying here is correct, then the at higher RPM, more voltage flows, then that would make sense.

    I tried two different FCoRs, one from a later CBR600F2, and both do the same thing, at idle RPM, they both supply between 8 and 9V to the pump.

    How is this achieved? A mate who is better at electrickery than I am, says the wiring diagram shows a device of some sort on the line between the FCoR and the pump that he says might be responsible for the voltage drop. However, on stripping back the loom, there is a single white wire completing that circuit, and there is no apparent device in it, but the resistance of this short run (no more than 100mm) is 4 Ohms, which seems high, but seems consistent with the ‘something in there’ theory.

    I've managed to get a spare old pulse generator coil assembly and fit it, I'll be firing it up tonight (fingers crossed), but I’m just intrigued to know what the story is with the fuel pump and its apparent voltage issues.

    Cheers,

    A
    The VF1000 is a different engine than the vfr700/750 we are talking about in this thread, but are similar in theory. The pulse generator coils by the crankshaft don't have anything to do with the fuel relay. They provide the signal to the ecm/spark box. That's all.

    Getting back to the fuel relay, it needs a series of pulses to provide output. I don't have a wiring schematic for a vf1000, but the similar VF750 uses 2 spark boxes. Each box has a yellow wire coming out that provide 12 volt pulses. One boxes yellow wire goes to the tachometer and the other boxes yellow wire goes to the fuel relay. The fuel relay is an analog circuit, nothing digital about it at all. I don't know how it works inside the relay, but image you had an analog volt meter with a needle that swings back and forth. If you apply 12v to it, it swings over to 12v. Now if you start touching it to 12v rapidly on and off the needle doesn't have time to swing all the way over to 12 or all the way back to 0v. A decent steady pulse will make the needle kind of hover in between.

    When the engine is idling it's a slow pulse which may only let 9 volts pass. It higher rpm the pulse is much quicker so you start to see higher voltages. If the engine stalls out with the key on, the pulses stop and the relay sends out no voltage.

    I hope that makes sense.
    Front end swap from 1990 Kawasaki ZX7 sportbike, taller police handlebars and Daugherty revalved rear shock. 97 CBR1100XX brake and clutch master cylinders. 98 VFR800 Euro switches. Euro turn signals. Yoshimura 4-1 exhaust. Hayabusa adjustable shifter. Universal gear indicator. Custom chain oiler. Koso EX-02S speedo. Working on slightly extended swing arm with Kawi rear wheel/170 tire.

  27. #26
    Senior Member JasonWW's Avatar
    Join Date
    Apr 2012
    Location
    Hou. TX
    Country
    My Ride
    86 VFR700F2 Pearl White
    Posts
    631
    Thanks
    3
    Thanked 31 Times in 31 Posts
    To clarify on what I was saying earlier:

    The 86 VFR700/750 gets its fuel relay signal from the yellow/green tachometer output wire from the spark box/ecm. It splits after coming out of the spark box. One to tach, one to relay.

    The 87 VFR700/750 gets its fuel relay signal from the number 3 ignition coil through a red/blue wire.

    The 88 and 89 VFR700/750 gets its fuel relay signal from the number 4 ignition coil through a red/yellow wire.

    I hope this doesn't confuse anyone, but the reason the 86 model is different in that it's fuel relay signal does NOT come from an ignition coil wire is due to the coils firing half as often as the 87 up bikes. The 87 up bikes fire their ignition coils every crank rotation (what's called wasted spark) and the 86 bikes fire only once every 2 rotations. Hence why the 86 bikes use a cam position sensor and the 87 and up do not. It's also why the 86 bikes need a special double fast output from the spark box to run the tach and fuel relay.
    Front end swap from 1990 Kawasaki ZX7 sportbike, taller police handlebars and Daugherty revalved rear shock. 97 CBR1100XX brake and clutch master cylinders. 98 VFR800 Euro switches. Euro turn signals. Yoshimura 4-1 exhaust. Hayabusa adjustable shifter. Universal gear indicator. Custom chain oiler. Koso EX-02S speedo. Working on slightly extended swing arm with Kawi rear wheel/170 tire.

  28. #27
    Junior Member
    Join Date
    Aug 2006
    Posts
    7
    Thanks
    1
    Thanked 0 Times in 0 Posts
    Quote Originally Posted by JasonWW View Post
    The VF1000 is a different engine than the vfr700/750 we are talking about in this thread, but are similar in theory. The pulse generator coils by the crankshaft don't have anything to do with the fuel relay. They provide the signal to the ecm/spark box. That's all.

    Getting back to the fuel relay, it needs a series of pulses to provide output. I don't have a wiring schematic for a vf1000, but the similar VF750 uses 2 spark boxes. Each box has a yellow wire coming out that provide 12 volt pulses. One boxes yellow wire goes to the tachometer and the other boxes yellow wire goes to the fuel relay. The fuel relay is an analog circuit, nothing digital about it at all. I don't know how it works inside the relay, but image you had an analog volt meter with a needle that swings back and forth. If you apply 12v to it, it swings over to 12v. Now if you start touching it to 12v rapidly on and off the needle doesn't have time to swing all the way over to 12 or all the way back to 0v. A decent steady pulse will make the needle kind of hover in between.

    When the engine is idling it's a slow pulse which may only let 9 volts pass. It higher rpm the pulse is much quicker so you start to see higher voltages. If the engine stalls out with the key on, the pulses stop and the relay sends out no voltage.

    I hope that makes sense.
    OK, that makes sense. However, on the P/G assembly wiring, there are five wires from the connector, 2 each for the coils, and then another for signal to relay?
    I know it might go through the ignition box, but it was my understanding that it was one of the pulse coils (2,4) that originated the signal for the cut off relay, so that it was not just key on dependent.

  29. #28
    Senior Member JasonWW's Avatar
    Join Date
    Apr 2012
    Location
    Hou. TX
    Country
    My Ride
    86 VFR700F2 Pearl White
    Posts
    631
    Thanks
    3
    Thanked 31 Times in 31 Posts
    Quote Originally Posted by Ascalon View Post
    OK, that makes sense. However, on the P/G assembly wiring, there are five wires from the connector, 2 each for the coils, and then another for signal to relay?
    I know it might go through the ignition box, but it was my understanding that it was one of the pulse coils (2,4) that originated the signal for the cut off relay, so that it was not just key on dependent.
    I found a schematic for the F model, not FF, but it should be the same. The 5th wire in the connector is for the oil pressure switch, so it's unrelated.

    You should have a blue wire from the 2-4 spark box going to the 2-4 ignition coil and that blue wire tees off and goes to your fuel pump relay.

    Front end swap from 1990 Kawasaki ZX7 sportbike, taller police handlebars and Daugherty revalved rear shock. 97 CBR1100XX brake and clutch master cylinders. 98 VFR800 Euro switches. Euro turn signals. Yoshimura 4-1 exhaust. Hayabusa adjustable shifter. Universal gear indicator. Custom chain oiler. Koso EX-02S speedo. Working on slightly extended swing arm with Kawi rear wheel/170 tire.

  30. The Following User Says Thank You to JasonWW For This Useful Post:

    Ascalon (12-21-2016)

Similar Threads

  1. 1 st. GEN. Fuel Pump
    By twowheelracer in forum 1st & 2nd Generation 1983-1989
    Replies: 20
    Last Post: 08-06-2009, 09:14 AM
  2. fuel pump
    By Mario98 in forum 5th Generation 1998-2001
    Replies: 1
    Last Post: 02-28-2009, 07:58 PM
  3. fuel pump
    By ats1080 in forum 1st & 2nd Generation 1983-1989
    Replies: 4
    Last Post: 06-30-2008, 10:16 AM
  4. Bad fuel pump.
    By rolling in forum 6th Generation 2002-2013
    Replies: 2
    Last Post: 05-22-2008, 10:27 AM
  5. 93 fuel pump
    By tbone in forum 3rd & 4th Generation 1990-1997
    Replies: 5
    Last Post: 07-16-2007, 11:55 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •