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  1. #1
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    Default converting to fuel pump on 1957 johnson seahorse

    We have model RDE-19 C Johnson Seahorse 35hp and we have been trying to get it going. (It was given to us) Anyway everything seems pretty good we even got the pressure tank but it has no fittings and the only ones I see online are around $95.00 for each and we need both ends. So we were wondering if it will be cheaper to convert it to the regulas gas tank type but I guess you have to add a fuel pump? Does anyone have any info or suggestions about this? Ive seen online about converting a smaller hp engine but nothing over 20hp so im wondering if you even can on these? Thanks in advance.

  2. #2
    Vice Admiral Scaaty's Avatar
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    Default Re: converting to fuel pump on 1957 johnson seahorse

    Screw the fittings..run lines right to the carb and the hell with it. Ya ain't gonna pull the motor off daily, and just refill the tank with a separate gas can. Laings outboards had new twin hose cheap, or just go to an auto store and get new hoses.

  3. #3
    Honorary Moderator Emeritus tashasdaddy's Avatar
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    Default Re: converting to fuel pump on 1957 johnson seahorse

    a agree with Scatty, just order some 2 line hose from Laingsoutboards.com, and 4 hose clamps, you in business. besure to get the air and gas line in the correct position. got mine backwards once. i find it highly foolish, to change a technology that has proven itself for over 50 years. just bought a 58 35 johnny. remember it's a 24-1 fuel/oil mixture.
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  4. #4
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    Default Re: converting to fuel pump on 1957 johnson seahorse

    Good suggestions so far. If you're really keen on a two-line quick disconnect fitting, keep an eye on the auction site for one...stuff like that comes up all the time. You can put a fuel pump on it, but if you have a functional pressure tank why bother? Converting will cost you close to $75 if you can find the parts used, then put a rebuild kit in them. Then you have to buy a modern tank and lines unless you have those already.

  5. #5
    Captain Drowned Rat's Avatar
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    Default Re: converting to fuel pump on 1957 johnson seahorse

    People sell those pressure tanks on ebay all the time not realizing how valuable the female fuel fitting attatched to it is. Take the fuel fitting off and turn around to sell the tank right back on ebay. Just keep your eye out. I see them go for about 40 to 50 bucks frequently. Laings sells the male ends for cheap. He's also got the replacement 0-rings for the female fuel fitting if it needs them. Good luck.
    “We do not inherit the earth from our fathers, we are borrowing it from our children.”

  6. #6
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    Default Re: converting to fuel pump on 1957 johnson seahorse

    Thanks for all the good suggestions, you all are great!
    I think we might have found a pressure tank with the fittings, we are biddding on it right now. I'll let you all know!

  7. #7
    Honorary Moderator Emeritus tashasdaddy's Avatar
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    Default Re: converting to fuel pump on 1957 johnson seahorse

    are you bidding against me. i bidding on a second tank for my 58 35. i've submitted my highest bid, good luck.
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  8. #8
    Vice Admiral Scaaty's Avatar
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    Default Re: converting to fuel pump on 1957 johnson seahorse

    Quote Originally Posted by Drowned
    People sell those pressure tanks on ebay all the time not realizing how valuable the female fuel fitting attatched to it is. Take the fuel fitting off and turn around to sell the tank right back on ebay. Just keep your eye out. I see them go for about 40 to 50 bucks frequently. Laings sells the male ends for cheap. He's also got the replacement 0-rings for the female fuel fitting if it needs them. Good luck.
    Can't agree here on ebay tanks. The connector is on the hose end, just clamps to most tanks pump nipples. The people buying them see or ask if it has the female connector, and with a decent tank go for close to a hundred anyway. Decent tanks are 40 -50. Just sold 2 totally repainted and clean with new gaskets. Male fittings are cheap (I have one if someone needs one) email me hogrider@myway.com


  9. #9
    Vice Admiral Scaaty's Avatar
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    Default Re: converting to fuel pump on 1957 johnson seahorse

    Quote Originally Posted by tashasdaddy
    a agree with Scatty, just order some 2 line hose from Laingsoutboards.com, and 4 hose clamps, you in business. besure to get the air and gas line in the correct position. got mine backwards once. i find it highly foolish, to change a technology that has proven itself for over 50 years. just bought a 58 35 johnny. remember it's a 24-1 fuel/oil mixture.
    Wow Bob, just sold off all good parts (which were just about all) from a 58 RDS 20 35hp. Had a mess of good parts. Scattered all over the US and Canada now

  10. #10
    Honorary Moderator Emeritus tashasdaddy's Avatar
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    Default Re: converting to fuel pump on 1957 johnson seahorse

    i sold one 3 months ago not knowing i'd ever need it. still have 1 i rebuilt. i like having enough fuel for the day.
    FLORIDA GATORS
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  11. #11
    Captain Drowned Rat's Avatar
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    Default Re: converting to fuel pump on 1957 johnson seahorse

    Yeah, I meant ones that have the fitting on there. You can usually see it in the photo. I've bought two tanks that way.
    “We do not inherit the earth from our fathers, we are borrowing it from our children.”

  12. #12

    Default Re: converting to fuel pump on 1957 johnson seahorse

    That Fitting I Saw It Listed For $ 136.00

  13. #13
    Vice Admiral jay_merrill's Avatar
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    Default Re: converting to fuel pump on 1957 johnson seahorse

    I'd convert the motor. Its easy, inexpensive, and you can use a very large variety of tanks with your motor.

    There is a "sticky thread" here, on how to do it. The "cliff notes version" is that you can use a bypass cover off of a later year 28hp/33hp motor, or you can use the original bypass cover.

    If you use the 28hp/33hp bypass cover, the procedure is a simple swap and mounting of a new fuel pump. If, on the other hand, you use the original, you will have to drill out the center "boss" (all three are actually there, but were never drilled) all the way through the cover, and the mounting bosses part way through. Those mounting bosses then need to be tapped for the mounting screws.

    One peculiarity of the old covers, is that the mounting/pulse bosses are molded very slightly higher into the bypass cover, than is true on the newer ones. Because of this, the Throttle Control Rod (steel rod, port side of motor) will hit the top of the fuel pump if it is mounted right side up. The fix is easy, just mount the fuel pump upside down.

    If you make the conversion, don't forget to remove the nipple on the lower portion of the intake manifold, which is the source of pressure for the hose/pressure tank. You will have to plug it will a small bolt of the appropriate size, thread count and length ..... do not use a screw that is too long because it will hit the Leaf Plate, located behind the intake cover (internal), if you do!

  14. #14
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    Default Re: converting to fuel pump on 1957 johnson seahorse

    i took a 6 gallen johnson tall boy to the dump a year ago... it was gnarly...but now i am haveing the darnest time finding a new one...

  15. #15
    Vice Admiral nwcove's Avatar
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    Default Re: converting to fuel pump on 1957 johnson seahorse

    DSCF1642.jpgDSCF1641.jpgoutdated thread cob, but is this what you refer to as a "tall boy" tank?
    give a man a fish, and he will eat all day. teach a man how to fish, and he will sit in a boat all day and drink beer.

  16. #16
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    Default Re: converting to fuel pump on 1957 johnson seahorse

    Thats it Tim. They were offered from '49 to '51 on the 10hp QD and 16hp SD for Johnson. Evinrude offered them for the 14hp Fastwin. Actually, Johnson may have offered them for the 25hp RD as well, but not sure on that one.

  17. #17
    Vice Admiral nwcove's Avatar
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    Default Re: converting to fuel pump on 1957 johnson seahorse

    100_1297 (3).jpg......heres the qd that the tank came with, great powerhead, but the overly complicated linkage set up has been mauled sometime during its life. poor thing is last on the list to try to revive! lol

    edit: thats not my 10 hp or my basement. not sure where that pic came from.
    give a man a fish, and he will eat all day. teach a man how to fish, and he will sit in a boat all day and drink beer.

  18. #18
    Fleet Admiral HighTrim's Avatar
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    Default Re: converting to fuel pump on 1957 johnson seahorse

    Is that your tank in the first pic Tim? Looks like the wingnut is still there, usually broken off.

  19. #19
    Vice Admiral nwcove's Avatar
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    Default Re: converting to fuel pump on 1957 johnson seahorse

    that is my tank in the first pic, but there is no wingnut . the shaft where i "think" it would go is there and intact tho.
    give a man a fish, and he will eat all day. teach a man how to fish, and he will sit in a boat all day and drink beer.

  20. #20
    Fleet Admiral HighTrim's Avatar
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    Default Re: converting to fuel pump on 1957 johnson seahorse

    Make sure if you use it that it is open. It is a shut off for transportation.

  21. #21
    Vice Admiral nwcove's Avatar
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    Default Re: converting to fuel pump on 1957 johnson seahorse

    the tank will probably never be used by me.....im a convert!!DSCF2061.jpg
    give a man a fish, and he will eat all day. teach a man how to fish, and he will sit in a boat all day and drink beer.

  22. #22
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    Default Re: converting to fuel pump on 1957 johnson seahorse

    Quote Originally Posted by tashasdaddy View Post
    a agree with Scatty, just order some 2 line hose from Laingsoutboards.com, and 4 hose clamps, you in business. besure to get the air and gas line in the correct position. got mine backwards once. i find it highly foolish, to change a technology that has proven itself for over 50 years. just bought a 58 35 johnny. remember it's a 24-1 fuel/oil mixture.
    I need help posting a question about my outboard motor how do I post question?

  23. #23
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    Default Re: converting to fuel pump on 1957 johnson seahorse

    Glad you asked. This thread is 7 years old, and should be put back to bed.

    Go back to the first page of the thread, at the top of the list of topics. You will see a big long red button saying POST NEW THREAD, or something to that effect. Click it and follow the prompts.

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