1954 Johnson Seahorse 10hp

Navsterboat · Jun 23, 2011

I recently purchased a 10hp Seahorse. It is super clean however after installing a Mikuni pump and shortening the hose for the vacuum pulse, it continues to shut off.
I was able to start it and it ran in iddle for a few seconds, then began iddling faster untill it cut off. I cleaned the carb inside and out and rechecked my work after it stalled. I did notice that the water in the tank had a good amount of oil, which leads me to wonder it its something wrog beyong a dirty card or inneffective fuel pump. Any information would be greatly appreciated.

1946Zephyr · Jun 23, 2011

Re: 1954 Johnson Seahorse 10hp

It looks like it's time for a spark test. Time to inspect the coils too and make sure the insulation is not cracked. If it is, then they'll arc out on the mag plate.

Navsterboat · Jun 24, 2011

Re: 1954 Johnson Seahorse 10hp

Picking up new coils and ignition tune up kit tommorrow; will have to wait to install after a work weekend. Hope to get those old screws out without cracking anything. Thanks for the info!!

Chinewalker · Jun 24, 2011

Re: 1954 Johnson Seahorse 10hp

Did you block off ONE of the holes in the reed plate when you did the conversion? If not then you will not get a pulsing action on the pump. Remove the flapper valve and fill in or cover one of the holes under the flapper. I used JB Weld on the last one I did...

nwcove · Jun 24, 2011

Re: 1954 Johnson Seahorse 10hp

if you havent already done it, do a search on how to do the fuel pump conversion, tons of great info on it! as chinewalker stated, it wont work unless done correctly.

levi_tsk · Jun 24, 2011

Re: 1954 Johnson Seahorse 10hp

agree with chinewalker and nwcove youve gotta block off the hole really good ... i used a BIG glob of RTV AND a vacuum plug and waited 48hrs to run it before that it still leaked and didnt run right....

Navsterboat · Jun 25, 2011

Re: 1954 Johnson Seahorse 10hp

Thanks for the info, I already did the conversion and plugged one of the holes and let it dry, ordered the coils and ignitiontune up package. The sparks are good just need to gap them, will adjust them as some of the previous posts suggested. Wish me luck and thanks again! Enjoy the weekend!!!

DallasJeff · Jun 25, 2011

Re: 1954 Johnson Seahorse 10hp

Nice motor. I'm still using the pressurized gas tank (two line) for mine.

Anybody know of a good source for parts and part numbers for this motor? I'm in need of several parts including the fuel bowl o-ring, fuel bowl filter stone, and some drive pins / shear pins. Thanks.

kfa4303 · Jun 25, 2011

Re: 1954 Johnson Seahorse 10hp

You can get a lot o f the parts right here at iboats. You can enter your make and model and all the available parts will pop up. Scroll to the top of the page and click on the "Marine Store" tab in the top left corner and go from there. Great lookin' motor.

DallasJeff · Jun 25, 2011

Re: 1954 Johnson Seahorse 10hp

kfa4303 said:
You can get a lot o f the parts right here at iboats. You can enter your make and model and all the available parts will pop up. Scroll to the top of the page and click on the "Marine Store" tab in the top left corner and go from there. Great lookin' motor.

Thanks, but having trouble finding that. Where do I enter the make and model? I went to marine store and entered "qd-15" in the search field but got nothing other than an owner's manual.

Johnson QD-15

I'll order all my parts from here if I can find them.

1946Zephyr · Jun 26, 2011

Re: 1954 Johnson Seahorse 10hp

DallasJeff said:
Nice motor. I'm still using the pressurized gas tank (two line) for mine.

Anybody know of a good source for parts and part numbers for this motor? I'm in need of several parts including the fuel bowl o-ring, fuel bowl filter stone, and some drive pins / shear pins. Thanks.

Wow, nice motor. It looks like it had good care.

kfa4303 · Jun 26, 2011

Re: 1954 Johnson Seahorse 10hp

DallasJeff said:
Thanks, but having trouble finding that. Where do I enter the make and model? I went to marine store and entered "qd-15" in the search field but got nothing other than an owner's manual.

Johnson QD-15

I'll order all my parts from here if I can find them.

Try starting here:

http://www.iboats.com/Johnson-Outbo...8247216--**********.230819661--view_id.271265

Once you've clicked on the type of part(s) you need, you should see two search boxes on the right hand side where you can enter your motors year and/or horsepower. You won't be able to search using model name and numbers. here' s the page for tune up kits to get you started. Good luck.

http://www.iboats.com/Johnson-Tune-...8247216--**********.230819661--view_id.271401

Navsterboat · Jul 1, 2011

Re: 1954 Johnson Seahorse 10hp

Ok so the coils are changed, there is a spark and it turned over; however, it continues to iddle then revs up and it dies out. It still. Hard to start so the only thing that I ampuzzled about, is wether the points need to be set with an ohm meter. Me being an RN, makes me think I may be out of my league on this. Appreciate all the info has gotten me this far. Oh and I don't want to take it to a marina, too many big jobs so mine gets put at the bottom of the list.

Navsterboat · Jul 1, 2011

Re: 1954 Johnson Seahorse 10hp

Looks like the seal on the hole failed hav e to try something better. Always recheck your work

Chinewalker · Jul 1, 2011

Re: 1954 Johnson Seahorse 10hp

This is not an electrical issue. The "revs up and dies out" is classic symptom of running out of fuel. A 2-stroke will speed up with a leaner fuel mixture, which is what is happening as it runs out of fuel. Double check your fuel pump installation...

nwcove · Jul 1, 2011

Re: 1954 Johnson Seahorse 10hp

nice motor! i agree with chinewalker, that sounds the same as a "no fuel issue". if your conversion isnt done right, or leaks , the new fuel pump wont get the "pressure/vacuum" pulse it needs to make the fuel pump work.

Navsterboat · Jul 3, 2011

Re: 1954 Johnson Seahorse 10hp

So after intalling the Mukini pump and shortening the hoses, re sealing the holes with epoxy and allowing it to dry for 48hrs, cleaning the carb and ( the float remained the same corck float, it was in good shape) and removing the original metal filter; removing and installing new coils and points (yes it does spark); the motor continues to run out of gas!!! it starts, revs up and eventually dies out. While it was running on one of these attempts I pumped the single line pump on the hose and the motor continued to run and iddle nicely, however without my assistance it would rev and die. The carb was rebuild, with the exception of the float as previously mentioned. I attempted to attach some pictures, hope they transferred. Any info is always appreciated. Oh and the power head came off, just to see what it looks like, have to get it cleaned, looked like a mess.

Daviet · Jul 3, 2011

Re: 1954 Johnson Seahorse 10hp

If it continues to run by pumping the primer bulb, you have a fuel pump problem. Remove the pulse line form the pump and crank the engine over, easier to do with the plugs removed, and see if you are getting a pulse in the line.

Navsterboat · Jul 3, 2011

Re: 1954 Johnson Seahorse 10hp

So the seal is holding like it should, and there is a pulse when the engine is cranked with the plugs on. I did not feel a pulse with the Mikuni pump; I have a OMC pump that came with my old 18hp that is useless and have a great pulse, it squirted with good pressure. I took the carb apart and put the spring the new carb kit came with (will consider ordering new float but, this one seems in good shape); also replaced slow speed needle and set them as instructed. As of now I am confident the work I've done is correct; also considering buying a pressure gauge to checke the pressure but not sure how to do it or whre to even start; will try again tommorow now that the spring is in place and reasured I have a good pulse pressure; thanks for the advise, have a safe 4th of July and GBA (God Bless America!!!!).

DallasJeff · Jul 3, 2011

Re: 1954 Johnson Seahorse 10hp

Daviet said:
If it continues to run by pumping the primer bulb, you have a fuel pump problem. Remove the pulse line form the pump and crank the engine over, easier to do with the plugs removed, and see if you are getting a pulse in the line.

Agree. Something's wrong with the fuel pump. Your carb and high speed/low speed needles are fine. Points are fine, plugs are fine. Problem is that fuel is not getting into the bowl unless you pump it by hand. Vacuum leak or incorrect fuel pump installation.

"The intake manifold is fitted with passages and also with ?check valves? that permit pressure but not vacuum to be fed to the hose barb and then via hose to the pressure tank. In order for our new pump to work, we need to totally block the flow of pressure from one cylinder, and to remove the check valve from the passages from the other cylinder so that we get both pressure and vacuum from just that one cylinder. If one merely removed the check valves but did not close-off the passage from one of the two cylinders, the alternating pressure/vacuum pulsations from the two cylinders would cancel each other out. Once these modifications have been made to the intake manifold, the rest of the conversion merely involves mounting the pump somewhere on the engine, coupling a hose from the pump to the hose barb on the intake manifold, running a hose from the pump to the?quick connector? mounted on the engine, and finally running a hose from the pump to the carburetor."

1954 Johnson Seahorse 10hp

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