Cleaning carbs

Discussion in 'Mechanics Garage' started by TOE CUTTER, Apr 22, 2009.

  1. squirrelman

    squirrelman Member

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    How many miles on that bike ?? Some carbon buildup on valve stems is normal and increases with mileage, but also increased by carbs running too rich or by weak valve stem seals.

    Stains in V most likely due to leaky float bowl gaskets or fuel tube O-rings.
     
  2. JasonWW

    JasonWW New Member

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    If you have compressed air you can bump the motor to close the valves and use a screw driver to gently scrape the majority of the crud off the valve and then use a tube on the compressor nozzle to extend down to the bottom and it will blow the debris up and out. (Just shooting compressed air from the top of the intake just blows it around)

    The last remnants you can try some carb cleaner to dissolve it. The small amount of dirty fluid won't hurt anything.
     
  3. Glenngt750

    Glenngt750 New Member

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    Thanks for the tips! I'll try to clean in there.
    I finally can upload a couple of pics. I see the outside of the carbs also have some kind of contamination. Bike has 26,000 miles on it. Has sat for ten years I was told. DSCN0444.jpg DSCN0445.jpg DSCN0449.jpg DSCN0454.jpg DSCN0457.jpg
     
  4. Gaspeddlers

    Gaspeddlers New Member

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    Hey everyone, didn't want to start a new thread, because this one was up in my garage while I was cleaning my 86 VFR750F carbs... (non-California bike). When I began work on the carbs the fuel pump worked beautifully, so good that I was able to taste the fresh gas I put in the tank! Now I installed my carbs, got everything back on and the fuel pump is making a ticking noise once upon the key turn, and second when I press start.

    I removed the black cap on the end and I see an arc between the points on the fuel pump, and I don't know if replacing that would fix the issue? Has anyone had a similar issue, is it just something easy to repair? Or do I need a new fuel pump?

    If so the current Ebay $27 special looks very promising, any pitfalls I should be aware of?

    I went ahead and purchased it just in case, here is the link to the listing I bought:

    http://www.ebay.com/itm/231504074718?_trksid=p2060353.m2749.l2649&ssPageName=STRK:MEBIDX:IT
     
  5. THRASHED

    THRASHED New Member

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    Not sure what would cause the sparking, but because I work as a firefighter at an oil refinery I can say with some authority that electrical arcs and gasoline do not mix...:flame::flame:

    As to your eBay purchase, I'm curious to see how that goes. I saw that and considered buying one ($160 for OEM is a bit steep) but was wondering how it works with the stock rubber mount and hose routing because my 87 has curved tubing. Would like to see some install pics when you get it in.
     
  6. Gaspeddlers

    Gaspeddlers New Member

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    The points inside the cap of the externally mounted fuel pump (which are sealed off from the atmosphere/fuel) have a gap between them. Does anyone know what the normal operation for the electric fuel pump is? What would a functional fuel pump behave like? It was just working two days ago when I began work on the carbs.

    Also I am not worried about the tubing, I can run new fuel line if needed, and the rubber mounts are shot on my OEM pump so the metal will have to support it enough for now. What I am worried about is something I read before stating that the aftermarket fuel pumps continue to pump fuel after the run switch is off and only quit when the key is off.
     
  7. squirrelman

    squirrelman Member

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    Last edited: Aug 2, 2015
  8. JasonWW

    JasonWW New Member

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    This all sounds normal. The contact points might need a little cleaning so as to reduce the arcing. If the contacts are really worn they can be replaced fairly inexpensively.

    These are low pressure pumps, so they will pump until the head pressure gets up to 1 or 2 psi. Once your float bowls are full the float needles should close off the inlet and pressure in the lines goes up which causes the pump to stop.

    There are several videos on YouTube just search for fuel pump contacts. Many bike manufacturers use this design. In normal operation, when you turn on the key the pump should be silent as the safety relay detects the engine is not running and shuts off power to the pump. Once you start cranking the bike or it starts running, then power is applied to the pump and it will click a few times then stop as the float bowls should already be full. As the bike idles the contacts will click every couple of seconds. If the float bowls are empty like after a rebuild, expect the pump to click rapidly for several seconds while cranking while it fills the float bowls. To avoid cranking the engine over for such a long time it is recommended you jumper the fuel pump safety relay to make the pump come on. It will pump/click very rapidly for several seconds until the float bowls are full.
     
    Last edited: Jul 30, 2015
  9. Gaspeddlers

    Gaspeddlers New Member

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    Problem found: The fuel pump relay seems to be malfunctioning. I'm not 100% sure what the best way to test this is, but no matter where I hook my voltmeter leads I get no voltage. Would this also cause the bike not to turn over? When they key is turned everything comes on (except for the fuel pump) and when I switch to run no fuel pump, when I press start the headlight goes off but the engine doesn't turn over. Will the fuel pump relay being installed allow a circuit to be closed or do I have another issue? Thanks for the help so far everybody the last post made me look past the fuel pump as it was jumpering correctly when I tried that.
     
  10. squirrelman

    squirrelman Member

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    You have another issue. No fuel pump or pump relay problem will cause the engine not to crank over (before it starts).
     
  11. JasonWW

    JasonWW New Member

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    Squirrelman means "You have another issue. No fuel pump or pump relay problem will NOT cause the engine not to crank over (before it starts)."

    Is your engine not turning over when hitting the start button? If so, that has nothing to do with the pump.

    Is your engine turning over, but not firing up? Check the drains to make sure there is fuel in the carbs. If empty,
    there is a method to temporarily bypass the fuel pump safety relay to fill the carbs with fuel. If you need that info I can do a search and post it here.
     
  12. Gaspeddlers

    Gaspeddlers New Member

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    I am familiar with the relay bypass, and honestly I am - one jump box so I did not try to jump it off. It may be a battery issue as it began in the shop with no tampering with the starting circuit whatsoever. I will get more info later tonight when I get back to the bike. I do think my fuel pump relay is dead because I jumpered my fuel pump and its making noise, but when the bike was cranking a couple days ago the fuel pump was doing nothing. This leads me to believe the relay is gone. I wont know for sure until I get it to crank again though no use wasting your guys/gals time on that.

    I can foresee myself asking for an alternative to the OEM fuel pump relay if that happens to be the problem. I have searched preemptively and have not found much guidance, and I am by NO means an electrical guy.
     
  13. JasonWW

    JasonWW New Member

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    I don't think there is an alternative relay. They rarely go out and are used on many Honda models so getting a working used one or a new one is pretty easy. Some guys remove them entirely so that the pump gets power when the key is turned on. That works, but it's not safe. If you get in a wreck and the engine stops, the pump would keep dumping raw fuel everywhere. That's dangerous to you if it ignites. It's dangerous to the bike if it floods the engine internals. Still, some guys bypass it.
     
  14. squirrelman

    squirrelman Member

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    I've had so many problems over so many years with pump relays crapping out that i always bypass them on every Honda i own. I'd rather worry about flames if i drop the bike than getting stranded some rainy night far from home. Turning off the key stops the pump.

    Another advantage to the relay bypass is much quicker starting with less battery drain, especially if it's been awhile since the bike was started.
     
  15. TOE CUTTER

    TOE CUTTER Mullet Man

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    Broke down for that very reason back in the day. Middle of nofuckingwhere. Wiggled a piece of rusty barb wire off an old cattle fence and bypassed it. Any mention of said relay brings it to mind.
     
  16. squirrelman

    squirrelman Member

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    A failed pump relay was the first problem i had on my first VFR in 1990, about 3 weeks after i bought it, so i learned my lesson early.
     
    Last edited: Mar 23, 2016
  17. NormK

    NormK New Member

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    Easy fix for replacing the relay is fitting a Carmtrol unit, not sure if you have them over there but out here they are used on cars converted to LPG to shut the solonoid down if the motor stops firing. They are very reliable and very rarely give any trouble and have an LED in them to tell you if it is working or not. I got one last week for $5 from a wrecker
     
  18. BluRoad

    BluRoad New Member

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    Back to the leaking fuel joint o-rings. If anyone needs replacements to fix it right, I can supply a small kit consisting of four new VITON o-rings, two grey Tygon lines and nice (easy to use) spring clamps. This line is expensive but is the only thing I've found to be flexible enough to easily make all the connections without straining or kinking. 1986-1993 VFR 700/750. Possibly other models/years, but I've not tried 'em.

    I'll ship the entire mess for $16 USD to anywhere in the continental U.S. $25 anywhere else. PayPal (friends & family) is okay.

    I'm not getting rich here— I just found, after 18 VFR projects, what works for me.

    JOE in IL
    V4Dreams.com

    IMG_0867.jpg IMG_0869.jpg
     
  19. cjolson140

    cjolson140 New Member

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    I have a 1987 VFR700F that developed a large fuel leak. I determined the source of the leak to be the fuel rail connection at the rear right carb... the plastic rail isn't cracked, so I assume the o-ring has failed. My plan was to replace all the plastic fuel and vent tubes with new metal ones I got on eBay. I was able to remove the carburetor assembly from the engine without too much trouble, but I am now unsure how to proceed.

    I've read that it's not advisable to separate the carburetors from the plenum, but that appears to be a necessary step of replacing the tubes? My Clymer manual doesn't have any detail about separating the carbs, or about the linkages between them. So I'm pretty hesitant to take it all apart. So my question is basically, is there a step by step procedure to replacing the fuel and vacuum rails? Sorry if this is a dumb question, and thanks for any advice!
     
  20. TOE CUTTER

    TOE CUTTER Mullet Man

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    It is necessary to remove the plenum when replacing the tubes, you just don't want to remove it before the carbs are pulled off the engine. I am not sure aboot a step by step but the real pit falls are the tubes themselves cracking during disassembly ,but you have new ones, the springs getting lost or misplaced and linkage placement.The best I can suggest is pay close attention and snap some good pictures for reference and cover a large work area with a white bed sheet to make locating the springs and miscellaneous parts easier than looking around concrete or carpet.
     
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