Fuel Pump Conversion Issue

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  • drifter

    US Member - 1 Year
    Replies: 192
    Topics: 124
    #251842

    Fuel is spitting and oozing out of the gold center of my B & S fuel pump. Is this due to a leaky diaphragm?

    Observation….Looking over the installation, I see fuel mix in the pulse line. Taking apart the pump, I see where fuel in the pulse line will exit a very tiny hole that is covered by the bronze (gold) center of the pump. So any fuel in the pulse line will ooze out the gold center.

    So, what to do? Is fuel in the pulse line normal?

    Is there a way to keep fuel out of the pulse line? I am getting the pulse by removing the check valve assembly and blocking off one side with a vacuum cap.

    If I can’t keep fuel out of the pulse line, would the pump still operate effectively if I sealed the gold center? I can hold a finger over the gold cap and blow/suck into the pulse line and feel/hear the valves opening and closing.

    Thanks for any insight on what to do next.

    small

    • This topic was modified 4 months, 3 weeks ago by drifter.
    • This topic was modified 4 months, 3 weeks ago by drifter.
    • This topic was modified 4 months, 2 weeks ago by Mumbles.

    crosbyman

    Canada Member - 2 Years
    Replies: 2717
    Topics: 269
    #251847

    the gold screen is for equalizing the diaphragm flexing under the action of the pulses no fuel should exit the screen . Before digging in to deeply have you tried another pump ??

    fuel in the pulse line may be accumulated fuel oil mix due to improprer crankcase drainage by the purge valve. if you have the manual see the section of purge valve cleaning

    some engines model have a crankcase drain hole in the left channel and no drain hole in the right side channel it is possible that using the right channel is better for such a conversion . I have a feeling the upper crankcase case cavity drains internally to the left side possibly reducing chance of any fuel-oil mix exiting via the pulse line.

    in any event tell us more on your exact modification procedure. all the the ones I did worked fine using B&S, Mikuni and square pumps

    btw… clear tubing is great to see things but may harden up fast if not fuel resistant type

    It is great for filling wine bottles but for “long term” may as well use the good stuff.

    Joining AOMCI has priviledges 🙂

    • This reply was modified 4 months, 3 weeks ago by crosbyman.
    • This reply was modified 4 months, 3 weeks ago by crosbyman.

    drifter

    US Member - 1 Year
    Replies: 192
    Topics: 124
    #251866

    Thank you for the help. I’m going to disassemble the intake plate and go over everything again and replace the gaskets, clean the purge valve, make sure the right channel (looking from the front) is blocked using the vacuum cap (as seen in the various you tube videos).
    Yes, the vinyl (clear line) is not the best but was used for ease of use to test the conversion. It did help in seeing the pulse line fill with fuel mix and watch the pump action moving fuel.
    This was my first attempt at a conversion after refurbishing some 30 motors using pressure tanks. I ran out of pressure tanks so thought I’d have a go at this one.
    Thanks again for you expertise and help.


    crosbyman

    Canada Member - 2 Years
    Replies: 2717
    Topics: 269
    #251867

    Check both pulse channels for a small hole at the end. since you are not filling the channels with sealant by using caps try the alternate channel as your pulse source & reassemble .

    have you seen the recent post on channelling all the crankcase residual fuel oil back to the tank ? a two line tank was used with the air line feeding the juices back to the tank instead of just air pulses

    A small mod on the purge valve allows all the normally “dumped in the lake” juice to be routed back to the fuel tank.

    Results seemed excellent both from an environmental perspective and I suspect fuel economy in the long run .

    I have a real nice CD11 I am fixing up and time permitting I may very well go that way 🙂

    these litle kickers eat up lot of fuel . my “trolling” 9.5hp 9622a eats up equal or more fuel than my 75 ETEC !

    Just for nostalgia…. I may retire it and switch my rig to the “purge modified ” CD-11

    Joining AOMCI has priviledges 🙂


    drifter

    US Member - 1 Year
    Replies: 192
    Topics: 124
    #251871

    The only manual I have is the Seloc manual. Can you tell me more about the purge valve cleaning? Is this the “crankcase drain leaf valve” shown in the parts manual?
    Can I remove the leaf valve and simply ensure the holes are not blocked? Squirt some carb cleaner?


    crosbyman

    Canada Member - 2 Years
    Replies: 2717
    Topics: 269
    #251875

    as a member you have access to the oldies “red bible”

    go to…

    MEMBERS ONLY tab click on INNERSANCTUM tab…..go down to the LIBRARY section click on GARRY SPENCER’S drop box go all the way down and find the red book logo

    click and download it to a PDF on your computer for storage. I got mine printed double side printed at a local print shop in 2 binders with plastic cover shets front and back

    Joining AOMCI has priviledges 🙂

    • This reply was modified 4 months, 2 weeks ago by crosbyman.

    crosbyman

    Canada Member - 2 Years
    Replies: 2717
    Topics: 269
    #251880

    see similar link

    1954 CD-11 Convert from 2 line to 1 line fuel

    Joining AOMCI has priviledges 🙂


    drifter

    US Member - 1 Year
    Replies: 192
    Topics: 124
    #251909

    Well, I took everything apart and meticulously checked everything I knew to check. The drain hole is clear (I used carb cleaner and compressed air). I removed the leaf valve and cleaned it along with the seats. Blocked the right hole (looking from the front). Reassembled everything and ran the motor. No change. The pulse line quickly shows fuel mix. After a few minutes of idling, the fuel starts to ooze out of the pump.
    The pump works fine and draws the fuel well. The motor runs well, starts easily and idles great.
    Guess I will return the motor back to the pressure system as I simply do not know what more I can do other than blocking the left hole or maybe going to a pump that does not have a bleed hole on the pressure side of the diaphragm (if such a pump exists). I can’t see the pump itself being at fault since the pulse line does fill with fuel.
    I do appreciate all of the help and I did learn a good bit.
    Thanks,
    Drifter


    crosbyman

    Canada Member - 2 Years
    Replies: 2717
    Topics: 269
    #251943

    did you try running the pulse line on the other channel ?

    the pump….Obviously a leaky pump is not acceptable but it seems your pump diaphragm does not mind the fuel/oil as a pulse medium versus just air pulsing .

    the fuel-oil & air mix acts as a hydrolic fluid and keeps things going as it flexes the diaphragm and the engine works ok

    I would try another pump before giving up on it. .

    I have one or two round B S pump… tomorrow I will try pushing some water in the pulse nipple to see it the gold screen leaks . I even suspect that that part of the pump should hold a pound or two of simple air pressure !

    Joining AOMCI has priviledges 🙂

    • This reply was modified 4 months, 2 weeks ago by crosbyman.

    drifter

    US Member - 1 Year
    Replies: 192
    Topics: 124
    #251949

    I do have another pump ordered as the pump I’m working with is an older one found in my parts stash. I have one of the larger rectangular silver Mikuni pumps (won’t easily fit under the hood) and one of the very small black square pumps. Guess I’ll try those just for the fun of it.
    The bigger silver Mikuni pump does not appear to have any air relief hole on the pulse side. I’ll give it a go.


    crosbyman

    Canada Member - 2 Years
    Replies: 2717
    Topics: 269
    #251985

    drifter…

    I did a pressure test 3-5 lbs psi on the pulse nipple of a B&S pump…well I did get loss of pressure upon release my pump indicating loss of air from the gold screen. plugging it with my finger holds pressure a bit longer but it does drop to 0 psi

    This would probably explain your loss (leak) of fuel/oil being pushed out of the engine air nipple into the pump cavity

    although I can not explain why you get so much juices from your crankcase….. the alternative is to try a different pump and see what happens. not being on site makes things a bit hard to evaluate.

    let us know if you find a cure

    Joining AOMCI has priviledges 🙂


    drifter

    US Member - 1 Year
    Replies: 192
    Topics: 124
    #251987

    Update…..Today I installed the square Mikuni pump and had success! I ran the motor for 25 minutes with zero issues.
    Observations: 1) There was still some bubbles of fuel mix in the pulse line but there was no indication that they caused any issue with performance.
    2) The pump pulled fuel well (at all speeds) through 7 ft. of line even with the tank sitting on the ground.
    3) This motor runs well but today’s runs was superb. Prior to today starts cold in 5 pulls but initially runs very rough (like heavily flooded or dropping a cylinder) for 2 or 3 minutes,
    then smooths out. Idled well, but a bit sensitive on needles. Today with the Mikuni pump, it started in 3 pulls and was dead smooth. Idle was “pokata pokata pokata slow! No
    sensitivity in the needle settings.
    4) Prior to today, there was no oil droplets on the surface of the water after extensive running. (I thought this odd as I’ve always had some oil spots floating on the surface of the test
    tank with all of my other motors). Today, the oil spots were there as in the past with all of my other motors.
    I will need to get creative as to mounting this pump.

    Thanks again for all of the great input. After many years at this hobby I know two things. 1) Great people in AOMCI and 2) I’m still learning every day.

    Mikuni-silver

    • This reply was modified 4 months, 2 weeks ago by Mumbles.

    crosbyman

    Canada Member - 2 Years
    Replies: 2717
    Topics: 269
    #251989

    great news great feedback … i’ll be watching for the round B&S pumps in the future ! I have a Jubile ready to test next spring….

    the Mikuni probably does not allow a pressure drop on the pulse going in so the engine can’t push the juices up the pulse line due to an air-lock effect

    Joining AOMCI has priviledges 🙂


    drifter

    US Member - 1 Year
    Replies: 192
    Topics: 124
    #252972

    Update…..Not one to give up, I pulled out my 1958 Johnson 7.5hp and made the exact conversion using the blocked right hand port and the same fuel pump. The pump worked well and the engine ran great, but, there was still some fuel mix entering the pulse line. No where near the amount that was seen in the 5.5hp Johnson. The fuel mix never actually oozed out of the gold center vent when on the 7.5, but the vent did get wet and the fuel mix was seen traveling up the pulse line to the B&S pump.
    Since the 7.5 has removable bypass covers, I decided to tap off of the bypass pulse. Using this method of obtaining a pulse worked perfectly. The pulse line remained clean. The pump easily pumped fuel through a 7 foot line with the tank sitting on the ground. After a 20 minute run almost all at slow idle, there was not a hint of a problem.
    This conversion does not require any disassembly of the intake plate. Just blocking off the pressure line. Conversion back to two line system is as fast as blocking the bypass line and connecting the two line fuel/air fitting back up.


    crosbyman

    Canada Member - 2 Years
    Replies: 2717
    Topics: 269
    #252974

    the 5.5 I sold to a neigbour with the modified channel trolls all day long yet…he does mention that the plugs foul up faster than he likes.

    Obviously the unburnt fuel oil mix which should,,…just drain out the purge valve are causing an overly rich mixture but the pump works fine

    yours seems to be pushing juices it out the “reassigned” pulse nipple normally these juices would end up back in the pressurized tank via the air line.

    I am still suspicious that your crankcase drain valve and/ or internal crankcase drain orifices may not be doing a good a job as they should ending up as excess juices in your pulse line

    pressure pulse wise I don’t think a fuel pump would care if it was being pumped with… liquids or just air but your B&S pumps don’t seem to like it . I can see the gold screen as an atmospheric balance feature to let the diaphragm flex both ways but why fuel actually leaks across the diaphragm and reach the screen is odd to say the least . could be crappy diaphragms being destroyed by the fuel ….

    if you plan to junk the B&S may as well open one up and look-see inside..for us!

    Joining AOMCI has priviledges 🙂

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