Electric Fuel pumps

Discussion in '4-Stroke Engines' started by Terminal Velocity, Sep 6, 2008.

  1. I'm exploring all options and right now I'm trying to figure out if I can use an electric fuel pump with the carburetor on the gxh50. I know that the electric pumps pump way more fuel than is necessary and at higher pressure (maybe I can find a low pressure pump at the auto parts store). Power for the pump isn't a problem as I have 15 pounds worth of a sla battery to power my headlights:cry:. So the question is, can I use an electric fuel pump or will it blow a gasket, flood the carb, etc.? Maybe this is a rode I shouldn't go down, but I commute 100 miles a day and I'm tired of filling up once on the way to work and once on the way home. I refuse to mount my 1 gallon tank above the motor...I just think its too high and honestly, I'm not sure I can safely secure it. I've even considered hooking the pump up to a swtich and periodically pumping fuel from a rack mounted tank to the the tank on the engine...

    I looked at the post started by sexwaxsurfer and found the mechanical "hockey puck" pump intriguing. I'd be very happy to use it, but nobody seems to be able to confirm how exactly it (the pump) ties in with everything and I can't afford to take the risk it won't work. Speaking of mechanical pumps, is it possible that they too can pump too much fuel to the carb? Any other suggestions?

  2. stude13

    stude13 Active Member

    why not attach metal water bottle for extra gas? i have a 28oz bottle.
  3. fetor56

    fetor56 Guest

    Hope u solve your problem as there is very little feedback from ppl that relocate their tank to BELOW carby height......i'm currently going down the route of a diaphram carby & am waiting for a new shipment to arrive from bicycle-engines.com.
  4. Skyliner70cc

    Skyliner70cc Active Member

    Use the pump to fill a header tank. Manual operation to shut if off once header tank is full.
  5. I carry spare fuel with me in a 30 oz MSR fuel bottle, but that still requires that I stop and fill my tank...too much work too often, plus its a time issue.

    I did find a low pressure fuel pump at partsamerica.com (1.5-4 psi) that is designed for carbs. Its a bit more than I wanted to spend so I'll probably keep looking ($43).
  6. jimraysr

    jimraysr Member

    Fuel Pump For Gxh50

    My engine came with a hockey puck pump that will run off the crankcase pulses.

    Honda provides it for the engines that come without a tank.

    I might use it and a larger single tank if I had your need.

  7. Jim, Have you actually hooked it up yet? I checked some service manuals and yes it does run off the crankcase pulses, but I'm not sure that putting a T in the line would provide sufficient pressure as that would contsitute a great big leak as far as the pump is concerned...thoughts?
  8. jimraysr

    jimraysr Member

    Hocky Puck Pump

    No I have not tried it as I haven't needed to use it. I am still looking for a round aluminum tank for behind the deat and might have to use it then.

    I did check the passages in the air cleaner for the crankcase vent line. It looks to be fairly restricted, thus offer a good amount of back pressure to the pump. the pump of course has a vent line from the other side of the pumping diaphragm. It is protected by a bronze sientered filter insert.

    I think if a restricter was required to make the pump operate, it would have been included. Then again instructions should have been included as well

    Honda seems to be short of technical information on line. Appears they want you to have to go to a dealer?

  9. do you suppose that if necessary the line from the crankcase can be run straight to the pump thereby completely bypassing the air filter without causing problems?
  10. little pump

    Hi I have not got mine figured out either, but maybe the line goes thru the pump, then into the airfilter?

    BTW I think an electric pump is definately overkill, why not mount the peanut, and plumb it into the tank like I did on two gebes?

    IF you think you want to go electric, ONLY use it as a transfer pump, you you'll not have to worry about overpowering your float needle in the carb.

  11. jimraysr

    jimraysr Member

    Hocky Puck Pump

    The pump only has three connections. Fuel in, fuel out and crankcase hose.

    You can tell as you can blow into one connection (fuel in) the air comes out one (fuel out) and the third one (pulse inlet)

    If you didn't connect the pulse line to a tee, I think it would blow off the line or build crank case pressure and force oil past the rings?

    The pump doesn't take much force to operate and the vent to the carb. inlet is needed to burn the blowby from the crankcase,

    Consider it only works because it is a one cylinder engine. The volume of the crankcase changes as the piston goes up and down. On a two cylinder as one pistion goes down, the other one goes up.

    I would think one large tank would be the best arrangement. As each tank needs a vent, the transfer pump, electric or pulse powered would over fill the main tank and leak out its vented cap.

    Good luck.


  12. biketec

    biketec Member

    I agree

    I have to agree with mike I think your best bet would be a spare tank and a pump to fill you primary source I want to do this as well I'm thinking of a trailer for my gear and in the back make a rack and maybe a 5 gallon with a pump and a switch say on the bars from radio shack drill your tank up top fit a nipple on it and BOOM you got 5 gallons on demand just an idea.OOH or you could have the rear rack mount as a reserve and your frame mount tear drop and do the same IDK but I do know you cant use a fuel pump and a pressure regulator on a simple float style carb its just gonna fill up and push the needle down with the pressure and rise the level to the over flow.... so I guess the best rout for the app I think your going for is a spare tank a pump and a switch or two tanks and say like a T and two valves ??? just some thoughts not an answer.
  13. jimraysr

    jimraysr Member

    Fuel Pump

    There is no reason the float carb won't work with a fuel pump. Honda provides the pulse pump with the GXH50.

    Any regular float type carb on a car handles 7# of pump pressure all day long. My 2 cylinder 4 KW Onan power plant on the motor home has a float carb and an electric pump. The pressure would have to be very high to push the rubber coated needlle off the seat with the leverage the float has.

    I still feel that one tank would work much better and have fewer problems.

    JMNSHO, Jim )
  14. biketec

    biketec Member


    I'm sure a pulse pump would work we have them but a pulse pump doesn't have a bowl and as for a float on a car is way different than one of these bikes I have seen these bikes get a sticky float on a bumpy road ... does that happen on your car? each carb has a set spring pressure for that app. these bikes have a super light spring, is all I was saying is the pressure would force the needle away from the hole and allow it to over fill, and not to mention I believe I said these were thoughts not answers.and as for just one tank that's an idea but why couldn't you run two for longer hauls? I was planning on riding mine home possibly and that's 2K away and I think it would be fun to make the trip with one fill up not to mention gas here is like half the price of CA anyway there just ideas and its all fun.
  15. These are all ideas and just for fun. There is one problem...I have to break away from fun (hard to do, even if it is for work:oops:) and get serious in that this is meant to be my primary commuting vehicle. Read as: I prefer reliability over all else. Foolish perhaps, but that's why I went through the extra expense of a honda motor and a chain drive from staton which until today seemed to be very reliable...more on that some other time. Anyway, the feedback I've been getting has been great so far. I would prefer a single tank with a pulse pump for simplicity's sake...if its reliable...but then again, if i'm looking for reliable maybe it would be better to keep two tanks. If the pump ever fails, I can still always stop at the gas station and feel confident I can go the next 50 and not be stranded. See, I like talking things out....thanks for all the help, and if anyone has any other ideas I'm still all ears...

    BTW Jim, I want to thank you for sticking with this post and answering my questions. Your help and input has not gone unnoticed!!
    Last edited: Sep 8, 2008
  16. biketec

    biketec Member


    I hear ya I have to ride my bike I cant drive I ride it 15 to and 15 back plus food and beer runs so I would say 35+ a day and if I diddent have it I would be up you know what creek I ride a 4stroke whoper stoper and so far so good .... sounds like it may have pooped out on you if theres anything I can do to help let me know (please dont take this the wrong way people) But I have all parts and I can find things in the back and I only say this as a fellow MBR and rely on it and want to help I'm not trying to peddle my wares and make a buck so if I can help I'm here for you.
  17. mct75

    mct75 New Member

    Perhaps a electronic float-switch in the small upper tank, not unlike what controls the filling of a toilet tank? That way, pressure does not matter, because the pump in the bulk reservoir cuts off before the top tank is full.
  18. loquin

    loquin Active Member

    And, if you want to use two tanks, plumb them in series, and not in parallel. Otherwise, the tank with the lowest head will get sucked dry, and then you'll be pulling air instead of fuel.

    Attached Files:

    Last edited: Sep 9, 2008
  19. jimraysr

    jimraysr Member

    Series fuel tanks.

    One consideration of the series piping shown in the diagram is the cap of the smaller "standard" tank must be sealed (unvented). Otherwise the tank with the higher head will overflow the lower head tank.

    Honda has an arrangement for a couple of their camping generators to run in parallel through a parallel wiring harness.

    In order to make this arrangement work more easily, they sell a third tank which has two outlets and these lines connect to each generator replacing the standard vented cap. Then as each generator uses fuel, it is refilled from the larger tank setting above both tanks.

    Unfortunately the cap of the China tank doesn't have a top vent hole, so you would have to find a cap that would fit and you could plug the vent.


  20. hmmm...decisions decisions. Whatever I do, I want it "simple"

    About the pooping out thing, the braze that holds the clutch drum to the shaft on the gearbox broke after 2300 miles and at precisely the right location to be the most inconvenient. What do I mean? Well, My commute is 48 miles one way. I figure with my current level of fitness I can probably make it to work on time if I break down mechanically within the first or last 10 miles of my commute...I leave that early. I'm hoping to increase that distance as I ride more (and pedal more) so that breaking down becomes less of an issue. The two things I fear the most about my commute is getting a flat (especially on the rear wheel...very time consuming to remove all the chains and put back together) or breaking down outside my "safe zone." Well, I was riding along with everything going okay and then all of the sudden the gearbox quits and i hear ZZZZZZZZZZZZZZZZZ or was it SCRAAAAAAAAAATCH...either way I thought I had lost my clutch that I had burned it up. NOt so once I took everything apart. Then I checked the tripmeter on my computer and it read 24.990 miles!!! Subtract from that the 1/2 mile I hoofed it to "safety" and you guessed it...I was smack in the middle of my commute when it broke!!!:evil: Such is life...Dave staton is sending me a new one that should be here on thursday, but in the mean time...