converting 2 line pressure to 1 line fuel pump Verified

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tashasdaddy

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i've been ask numerous times how i converted my 1958 35 seahorse from the pressure tank, to the fuel pump to work with the single line tanks.

disclaimer: this is for a 1958 35 hp johnson seahorse. you have to verify your on parts, and method of conversion. i will not be responsible for any screwups.

i started by ordering fuel pump 438562, bypass cover gasket for this engine 304784, and fuel connection 438793. you will have to verify the bypass cover gasket for your particular engine.

i remove existing connections, & bypass cover. had the 2 outer hole tapped for 10/24 bolts, and the center hole drilled out (this is for the pulse, to operate the pump) reinstalled cover with new gasket. mounted fuel pump to cover(don't forget gasket between cover and pump).

removed existing fuel connector, and replace with new. install new fuel line from connect to pump, will have to be bigger diameter to fit connections.

new fuel line from fuel pump to carb. and i just use the shade tree mechanics method of blocking the air line with a bolt into the line with a hose clamp.

make sure everything is tight. connect fuel line, and should be ready to run.
 

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tashasdaddy

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Re: converting 2 line pressure to 1 line fuel pump

here's what i drilled and tapped.
 

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tashasdaddy

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Re: converting 2 line pressure to 1 line fuel pump

i asked F_R to critique this, and he add this:
"That should answer a lot of questions. You might add the iboats number for the pump though. 18-7351. Also, you might point out that you got lucky on the bypass cover. Most people are going to have to find one with the pump mounting bosses."

i also have to give 99% of the credit for this conversion, to Frank, F_R, as he walked me thru this. this was my first conversion. there were others who helped. but Frank provided the pictures, from his motor, for me.

i had been a staunch advocate of keeping them original, because of the night mares i have heard, of people killing engines doing this.
 

F_R

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Re: converting 2 line pressure to 1 line fuel pump

Actually, there was a fuel pump conversion kit sold as an accessory when those motors were new. Here is an original picture of one with the factory kit installed. Also a newer 40hp with original installation. Note that there are several versions of the fuel pump through the years.
 

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rndn

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Re: converting 2 line pressure to 1 line fuel pump

What was the total cost and time for the retro? Nice work though.
 

tashasdaddy

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Re: converting 2 line pressure to 1 line fuel pump

i sold my 2 line pressure tank on ebay for $80.00. the cost was around $100.00 and i got the fuel pump, and connector on ebay. i took my time as not to screwup. probably 3 hours.
 

Texasmark

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Re: converting 2 line pressure to 1 line fuel pump

A tad of useless trivia. Back in those days, I was just a kid and didn't know what was going on. I thought he OMC tank and double line was COOL. I used it as part of my criteria for determining which mfgr I liked. I didn't know physically what was going on with the two hoses.

Course as I got older and actually bought one with some time on it, I realized that it wasn't all that cool. The single like with a fuel pump was much better.

Mark
 

tashasdaddy

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Re: converting 2 line pressure to 1 line fuel pump

mark, actually i have had no problems with the 2 line tanks, other than they are really expensive. only reason i did the conversion, was i need to have more than one tank in the boat for longer runs.
 

samo_ott

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Re: converting 2 line pressure to 1 line fuel pump

TD, that seems like a lot of extra work when all you needed to do was carry a jerry can of gas... (and hope for calm seas when transferring!)
 

tashasdaddy

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Re: converting 2 line pressure to 1 line fuel pump

no open containers in my boat, unless they contain alcohol.
 

samo_ott

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Re: converting 2 line pressure to 1 line fuel pump

My jerry cans have lids! :)
 

burroak

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Re: converting 2 line pressure to 1 line fuel pump

What was the total cost and time for the retro? Nice work though.

If anyone is thinking about doing this conversion, there is a fuel pump, hose, and motor side connector on Ebay.
 

Texasmark

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Re: converting 2 line pressure to 1 line fuel pump

Tas, my problem reference was to the connector which was well worn and kept the dual system from working properly....don't remember the specifics of the problem. Back then either I didn't know or couldn't afford to solve the problem. Was lucky to have the 5 1/2 Johny as it was.

Hear you on the open containers.

Hear you on the steady seas. When I would take my 13' boat 10 miles offshore (when I was younger and all that) I carried a spare can of gas and to fill the tank I would motor to the lee side of the island where it was calm.

Mark
 

tashasdaddy

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Re: converting 2 line pressure to 1 line fuel pump

Mark, your problem was probably the o rings in the connector. we didn't even know they were availble way back then. now they have complete rebuild kits for the tanks.
 

flyboy712

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Re: converting 2 line pressure to 1 line fuel pump

Here are a couple pictures of the fuel conversion that I did on my 18hp Johnson. Just took off the cover drilled out the hole with a 5/16" drill bit and tapped it with a 1/8" NPT tap. Screwed in a 1/8" barb fitting and hooked it up to the pump. I blocked off the pressure port on the bottom of the engine behind the carb. You can use either the top or bottom port I used the top one. The blue arrow is where I drilled the hole for the tap at. Make sure you remove the cover before drilling it or you will ruin your motor!!!!

It works great and it only cost me about $50 bucks the pump was $20 6 gal fuel tank about $20 and then the hoses and fittings.

http://i125.photobucket.com/albums/p75/joepilot78/Photo3.jpg

http://i125.photobucket.com/albums/p75/joepilot78/Photo2.jpg
 

samo_ott

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Re: converting 2 line pressure to 1 line fuel pump

Flyboy, is that a Mikuna pump? What model # did you get? or what is it otherwise? thx.
 

The-Machinist

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Re: converting 2 line pressure to 1 line fuel pump

Hey TD, did you ever find out why the old girl stopped cooling? I started up my 57' 35 rude after sitting a couple weeks and it's not cooling either. Just wondering if it was another sierra pump gone bad?
 

flyboy712

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Re: converting 2 line pressure to 1 line fuel pump

Yep it is the MIKUNI SINGLE FUEL PUMP part# 07-00777 $20.00 from Aircraft Spruce.
 

rolmops

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Re: converting 2 line pressure to 1 line fuel pump

Not to sound weird,but wasn't 1957 the last year that the 35 horse had the double fuel hose???
 

BoatBuoy

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Re: converting 2 line pressure to 1 line fuel pump

'58 was the last year I'm pretty sure. That year, the Sea Horse had a double line, the Super Sea Horse had a fuel pump.
 
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