1956 30hp Johnson Seahorse carb issue

[Herbal Gardens]

Hello all and thanks for reading my post, hopefully someone can help me out


Ive gone through the entire engine and am stuck-

I have excellent spark (new plugs coils ect) Ive rebuilt the fuel tank and replaced all the fuel/ pressure lines and have excellent fuel pressure to the engine. I have also rebuilt the carburator (had gas leaking out the needle valve seats) now there is no gas leak at all!

It idles fine no missing at all however when I took it out for its maden voyage. I let the idle carry me away from the boat launch (5/8mph) and started to accellerate but the engine didnt respond and started to get a hessitation. I set the controls on full throttle and let a friend steer while I started adjusting the needles. I fugured that I would start with the high speed needle sense the engine would idle fine but adjusting the high end did nothing. I decided I would turn the high needle until it bottomed out, I then opened it one full turn and moved on to the low end needle. (the throttle is still wide open and still no accelleration) I turned the low end needle in 1/4 turn and the boat took off and started to plane out. I thought I had the problem licked until I throttled down and the engine died. It started again without a hitch, and accellerated when I gave it gas but it is dogging bad and wont push the boat fast enough to plane out so I went back to adjusting the high speed needle (this is where I am at with the engine now)

I open the high speed needle just a tiny bit and the engine wants to die, so I start to close it off a bit and the engine takes off like it did when the boat planed out but starts dogging after a few seconds.....Ive done this dozens of times and nothing changes. Any idea's out there? I can't be the only person to run into this issue. Its slowly driving me insane

 

[F_R]

Re: 1956 30hp Johnson Seahorse carb issue

So, to summarize, you can get it to run properly if you adjust the high speed knob...but only temporarilly, right?

That shows that it CAN run right with a properly adjusted high speed knob.

I think you have other problems. Sounds like not enough fuel delivery to the carburetor. Float adjustment??? Clogged filter??? Some other restriction that I can only guess at??? Inadequate pressure in the tank???

EDIT: Hold on a minute. Re-reading your story, are you saying it continued to run with the throttle wide open and the high speed needle completely closed? That can't be right.

 

[Chinewalker]

Re: 1956 30hp Johnson Seahorse carb issue

More than once I've seen someone show me their "closed" needle valve only to see that it had merely run up against the stop or cowling. Is this adjusting being done with the cowling off so that the needle knobs can rotate fully?

 

[Herbal Gardens]

Re: 1956 30hp Johnson Seahorse carb issue

Yes all of the needle adjustments Ive made have been with the cover off.

As far as the full throttle comment, let me clairify alittle here:

I have the engine throttle control at max and at first there was no accelleration or increase in RPM's but after some adjusting it took off and brought the boat to a plane but only temporarilly

as far as having the high speed needle closed, yes the needle was all the way in and the engine continued to putt along at a high idle speed while the accellerator was at max- Hope this helps and sorry for the confusion

 

[F_R]

Re: 1956 30hp Johnson Seahorse carb issue

Well, first, make sure that thing is running both cylinders.

With the high speed needle completely closed, no fuel can get through, and it can't run. So something is screwy there.

 

[tmcalavy]

Re: 1956 30hp Johnson Seahorse carb issue

Read the carb adjustment post in the FAQ section. Tells you where to start with both needles, after you make the other checks: compression, fuel delivery, spark, etc.

 

[Herbal Gardens]

Re: 1956 30hp Johnson Seahorse carb issue

i have 120psi in both cylinders, and have checked both plug wires with a multimeter and am getting excellent juice to the plugs the points are gapped at 20 grand (per stamp on flywheel) the plugs are set at 30 grand (recomended per johnson manual) all new gas lines under the cover as well as the lines from the tank the tank pressure will read at 8 to 9 lbs on the high end (the release valve on the tank opens within this range)

the carb has a new kit installed no leaks at all, when I pressurize the tank and connect the line to the motor the glass bowl fills almost instantly without any air bubble in it. Howver I neglected to get a new filter for the engine, however I did spray the heck outta it with carb cleaner, I will get a new filter today and see if that is the culprit