1958 johnson 7.5 fuel pump conversion/location

[nwcove]

looks like space is tight to mount a mikuni pump to convert my 1958 johnson 7.5 to single line. has anyone done this with a mikuni pump, and made it look "tidy"? ive seen a nice job done with a b&s pump, but im going with the mikuni. is distance from the bypass cover an issue,.. if the pulse line is not kinked and stiff enough not to collapse under vacuum?

 

[HighTrim]

Re: 1958 johnson 7.5 fuel pump conversion/location

I fit the Mikunis under the carb on the QDs and Sportwins, but on the 7.5hp ADs and Fleetwins, I have not found a suitable, tidy location for it under the cowl, that is why I use the B&S pumps on them, as you have likely seen in my threads. They fit nicely on the bypass cover, whereas the Mikunis are a tad bulky.

You obviously want as short a distance on the lines as possible, but that is not to say that a longer stretch will not work. I have mounted Mikunis external from the cowl with success. I just dont like the looks of it, nor do I like it exposed to the elements. Would be a worse case scenario in my humble opinion.

 

[nwcove]

Re: 1958 johnson 7.5 fuel pump conversion/location

i was looking at the space above the carb, as close to the faceplate as possible, thus the query about pulse line length. there are two un-threaded holes on the bracket that the recoil mounts to, that look like a possible location for a fuel pump bracket....but i do have concerns about the carb linkage if the pump vibrated loose. ( wish i could get a b&s pump for a reasonable price.....pump is cheap....but $18 shipping,is a bit much!....your install does look clean)

 

[HighTrim]

Re: 1958 johnson 7.5 fuel pump conversion/location

I sent you a PM.

 

[nwcove]

Re: 1958 johnson 7.5 fuel pump conversion/location

thanks..i did look into it/set up ebay.....just waiting to hear back to confirm shipping rates. ( dont want any surprises!!) lol

 

[nwcove]

Re: 1958 johnson 7.5 fuel pump conversion/location

does it matter which bypass cover gets drilled and tapped? upper/lower??

 

[HighTrim]

Re: 1958 johnson 7.5 fuel pump conversion/location

Doesnt matter at all, I usually do the top, so that the hose coming off the bottom does not kink and has room to loop. But whatever is easiest.

 

[nwcove]

Re: 1958 johnson 7.5 fuel pump conversion/location

thanks hightrim, i finally typed in the right words in the search bar to find the pic you posted awhile back of the nice clean install of the b&s pump, but i see you drilled and tapped the lower cover for that one?

 

[HighTrim]

Re: 1958 johnson 7.5 fuel pump conversion/location

Yeah sorry just re read my post above, meant to say I MOUNT them on the upper bypass cover, but TAP the lower. My mistake.

Do not rely on that pic for the line hookups, I erred when I took the pic. Had to rearrange them properly afterwards. The middle nipple in the pic is actually the pulse, not the bottom like I have it.

Do the suck/blow test before installing. You should be able to blow, but not suck for the IN nipple. Suck but not blow for the OUT nipple. Suck and blow for the pulse.

You will also be able to faintly see the sheet metal I had to use to mount the lower mounting screw. The top screw I used the bypass cover bolt hole (I used a longer bolt to compensate for the pump thickness). The sheet metal was something like 3" x 1", coming off another bypass cover hole, then with an additional hole to secure the lower pump bolt to.

 

[nwcove]

Re: 1958 johnson 7.5 fuel pump conversion/location

thanks again, and i was gunna ask about the screw thats mounted to the lower right! but now i see what you did.

 

[nwcove]

Re: 1958 johnson 7.5 fuel pump conversion/location

would there be any known issues with raising the recoil assembly about 1mm to allow for a pump mounting bracket to be installed? it does look the the pawl engages the flywheel about 3mm down from the top. ( just dont want to spend the time making a bracket if its already been tried without success)

 

[HighTrim]

Re: 1958 johnson 7.5 fuel pump conversion/location

Couldnt say for sure myself, never tried. Youd likely want to raise all 3 mounting points to keep it square if you do.

You dont want to mount to the bypass cover?

 

[nwcove]

Re: 1958 johnson 7.5 fuel pump conversion/location

looked at mounting to the bypass cover, but it does look like a bracket can be mounted to the rear recoil mounting hole and the threaded hole thats located about an inch from it. i do realize that i will have to shim the whole recoil assembly up, to match the thickness of the bracket, just checking to see if anyone has went this route???

 

[nwcove]

Re: 1958 johnson 7.5 fuel pump conversion/location



finally "mocked up" the fuel pump. it does look like i will have to route the feed to the carb the long way around, but can anyone see any issues with this set up? the cowl does clear everything except the feed to the carb., the cowl does touch that line, and as mentioned, it looks as tho i can route that line around the powerhead on the tiller side and have good clearance. ( plz chime in hightrim, if i messed up on the suck/blow test , and have the inlet and discharge lines confused!)...sorry for the poor pic quality!!

 

[nwcove]

Re: 1958 johnson 7.5 fuel pump conversion/location



heres my final setup...without the fuel lines attached. from what i can tell, the bottom nipple is fuel out to the carb. it does look like that line will have to be routed under the head and around to the tiller side to connect to the carb . but so far it all clears the cowl.

 

[kfa4303]

Re: 1958 johnson 7.5 fuel pump conversion/location

looks good to me.

 

[1946Zephyr]

Re: 1958 johnson 7.5 fuel pump conversion/location

I have seen over a hundred types of Mikuni fuel pumps on ebay. It's pretty easy to find one that fits the mounting and hose arrangement needed for an old outboard. Chris' set up there looks great though.

 

[nwcove]

Re: 1958 johnson 7.5 fuel pump conversion/location

I have seen over a hundred types of Mikuni fuel pumps on ebay. It's pretty easy to find one that fits the mounting and hose arrangement needed for an old outboard. Chris' set up there looks great though.

hightrims setup, and advice was more than helpful for a reference to mount the pump. i just wanted to to use odds'n'ends i had in the junk drawer to mount the pump, and make it kinda look like it was meant to be there. ( yes...im cheap!! lol) .

 

[1946Zephyr]

Re: 1958 johnson 7.5 fuel pump conversion/location

Yea, that style pump he used there, looks to be the best set up, for an outboard. I'll likely be looking for for that type, when I convert some 5.5's.

 

[nwcove]

Re: 1958 johnson 7.5 fuel pump conversion/location

Yea, that style pump he used there, looks to be the best set up, for an outboard. I'll likely be looking for for that type, when I convert some 5.5's.

after the 7.5 is finished up, im on to a cd-13, that will be converted. just not sure of the pump type or location, im leaning towards a mikuni rectangular pump, and mounting it it above the carb...in all that empty space! just dont like the cable tie mounting deal, as i would like it to look like it was "meant" to be there. if anyone has tried to mount a pump above the carb and has had issue....plz chime in!!