Late 50's SeaHorse 7.5

Rusty Boater · Jan 31, 2008

Hey folks.

I have a question about my Seahorse 7.5. I believe it is around a 1957 model. It always starts with a few pulls and runs great. Last weekend I decided to start it up; been about 6 months since last start. It would not start; nothing. The plugs are about two years old and look a little black so i plan on changing them.

The funny thing is it has been switched over to a one line system and the bulb was very stiff and i hear a leaking air sound when pumped but no leaking fuel. Could that be the problem?

wbeaton · Jan 31, 2008

Re: Late 50's SeaHorse 7.5

Well, we certainly need more info. What is the Model number? Should be AD-10, 11 or 12 (1956-1958). Did you install a fuel pump when you switched to a single line tank? What pump did you use and how did you hook it up to the motor.

Rusty Boater · Jan 31, 2008

Re: Late 50's SeaHorse 7.5

I will look at the model number tonight. I inheritaed the boat from my Wife's grandad and he had it changed over to one line. I have had it for 4 years and ran fine on the one line system. It looks just like the system Tashasdaddy did on his.

steelespike · Jan 31, 2008

Re: Late 50's SeaHorse 7.5

First thing is to check for spark.If coils are original they will no doubt have failed.Very common and ignition parts are readily available right here at iboats among many other places.
If spark checks out then most likely the fuel system has become fouled up from sitting for long periods.Again most parts are readily available..

tashasdaddy · Jan 31, 2008

Re: Late 50's SeaHorse 7.5

buy a new fuel line. the bulb is shot. the check value is pumping and and sucking if back. vent open on fuel tank.

samo_ott · Jan 31, 2008

Re: Late 50's SeaHorse 7.5

And if you have good spark then spray some 25:1 pre mixed fuel n oil in the carb and if it fires up briefly then you have a fuel supply issue and probably need to clean the carb.

F_R · Jan 31, 2008

Re: Late 50's SeaHorse 7.5

If you have never checked the coils, they are long overdue. Those old coils had a 100% failure rate. Remove the recoil starter and the tin cover on the flywheel. You can then see the coils inside. If they are cracked or look like they are covered with dried-up sweat, you have found at least one problem exists.

JB · Jan 31, 2008

Re: Late 50's SeaHorse 7.5

Go to the Engine FAQs. Do "Outboard won't start".

Rusty Boater · Jan 31, 2008

Re: Late 50's SeaHorse 7.5

Is there a manual available on this?

samo_ott · Jan 31, 2008

Re: Late 50's SeaHorse 7.5

Yep, but you need the model #.

Rusty Boater · Feb 4, 2008

Re: Late 50's SeaHorse 7.5

Ok Weekend Update with Tina Fay...

Model # is AD-12. What year is that?

I got new plugs and have spark when plug is grounded on top of motor, nice pretty blue on both plugs.

What next? Fuel line. Someone on here said to spray fuel in the carb to see if it would start . I looked at the carb and i am not sure how to get the cover plate of with the mix adjustments and the choke button.

THANKS FOR ALL THE HELP!!!

wbeaton · Feb 4, 2008

Re: Late 50's SeaHorse 7.5

1958. There are two screws that hold the air silencer to the front of the carb and two that hold it to the motor at the back. You must remove those to access the carb. The whole procedure is nicely laided out on a 5.5 hp (which is basically the same as your motor) in the following link. The mixture and choke knobs are all held on by screws. You have to take them off.

http://www.outboard-boat-motor-repair.com/

Also, check those coils. Good spark against the block doesn't mean they are good. You need to take a look at them.

F_R · Feb 4, 2008

Re: Late 50's SeaHorse 7.5

Loosen the packing nut around the high speed adjustment needle, Just about 1/2 turn or so to loosen it up, then back the needle all the way out of the carburetor. Operate the primer pump on the tank and see if gas runs out the needle valve hole. If not, Ahah! If it does run out, screw it all the way back in, then back off 3/4 turn and retighten the nut. You are getting at least some gas. Oh, did I mention, look at the end of the needle and see if it's clean or if it's covered with varnish or goo. If dirty, you need to clean the carb and put in a kit.

Rusty Boater · Feb 4, 2008

Re: Late 50's SeaHorse 7.5

wbeaton said:
1958. There are two screws that hold the air silencer to the front of the carb and two that hold it to the motor at the back. You must remove those to access the carb. The whole procedure is nicely laided out on a 5.5 hp (which is basically the same as your motor) in the following link. The mixture and choke knobs are all held on by screws. You have to take them off.

http://www.outboard-boat-motor-repair.com/

Also, check those coils. Good spark against the block doesn't mean they are good. You need to take a look at them.

Can you direct me towards a write up on how to check the coils and remove the flywheel?

Also is there a manuel anywhere for this motor?

Thanks!

wbeaton · Feb 4, 2008

Re: Late 50's SeaHorse 7.5

The link I posted has everything you need to know to tune-up your motor. Look under the 5.5 hp tune-up procedure.

Visually check your coils by removing the rewind starter and inspection plate from on top of your flywheel. Then look at the coils. If they are cracked, sweaty or discoloured they are shot. If they have been replaced they are probably fine.

You can get service manuals from many places. Just do an internet seach. Factory manuals are usually best, however, I have both from that era and I don't don't think any are that great. I have a parts manual for a 1956 that is basically the same as yours that I could email you if you are interested.

Rusty Boater · Feb 4, 2008

Re: Late 50's SeaHorse 7.5

Wayne that would be GREAT!

Do you think those part numbers he lists for the 5.5 would be the same for the 7.5?

I know the carb kit is the same. More concerned with the impeller and ingnition parts.

Thanks agian for all the help!

russ.crumley@cccllc.com

wbeaton · Feb 4, 2008

Re: Late 50's SeaHorse 7.5

All parts are the same except the head gasket, but don't pull the head like he suggests anyway.

Rusty Boater · Feb 7, 2008

Re: Late 50's SeaHorse 7.5

So i pulled the recoil starter and the the inspection cover on the flywheel.

I must have some good karma; the coils where this beautiful blue and had no cracks and no dry looking sweat stuff. points looked nice and shiny as well. I may still replace the points & condensers though and check timing /gap. I think we have a fuel system problem. Thoughts?

F_R · Feb 7, 2008

Re: Late 50's SeaHorse 7.5

I think you have a fuel system problem too. Just didn't want you to proceed till you established what the coils were like. Now that you know that, do like I said and remove the high speed needle to see if there is gas in the carb. You probably have a stuck float, or the carb is gummed up. But you still need to do first things first and check like I said in order to see which direction to go in.

Rusty Boater · Feb 7, 2008

Re: Late 50's SeaHorse 7.5

Does anyone have a part number for the gasket between the powerhead and the "foot" unit for when i remove to replace the impeller?

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