Johnson seahorse 1982-84 4hp 2stk surging and then bogging out

[Markhugy]

Hi All,

I am currently at a loss with the above outboard. I ve cleaned the carb and replaced the plugs and still the outboard surges after running for 1 minute then cuts out.

I have a video of this if anyone needs me to send them it unless I can post the video on this forum.

Any help and advice is needed so I can get back on the boat asap.

Cheers
Mark

[Joe Reeves]

What's the model number of that engine?

[Markhugy]

Model number

Hi Joe,

The model number is: BJ4BRCOB

[Joe Reeves]

Hi Joe, The model number is: BJ4BRCOB

If memory served me properly, that model incorporates a on engine fuel tank. It also sticks in my mind that there was no filter in the tank to speak of... BUT... rather has some kind of filter funnel at the fuel cap area (weird setup).

Anyhow,,, check the connections at the tank that lead to the carburetor as it's always possible that there's some kind of filter there... something that would cause a fuel restriction..... which is what you're describing.

Also, at the extreme bottom of the brass vertical fuel nozzle, that screws into the upper carburetor body, is the small .031 ID high speed jet. It's always possible that something could be floating around the float chamber to clog that jet.

The above is assuming that the engine is not running hot and seizing to a stop. Let us know what you find.

[Markhugy]

Update.

Hi Joe,

I have stripped the tank this morning and there was a small filter inside the fuel tap when I unscrewed it. I cleaned it up started the engine and like before after a while at low revs it bogs out and within 20s at high revs it surges and cuts out.

I also checked the main jet that is inside the bowl which was all clear. You mentioned that it might be an overheat problem anyway I can check that out?

Cheers

Mark

[Joe Reeves]

To make sure that we're on the same page..... This slowing down to a stop problem.... Does this take place at "all" speeds including full throttle, or does it take place just at a idle rpm? I will insert the proper carburetor adjustment procedure here.
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(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.
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If the engine was overheating to a point whereas it was slowing the engine down to a stop... that engine would be smoking HOT! So hot that the pistons would be seized to the cylinder walls and it would be impossible to crank the engine with the manual starter until the engine cooled down somewhat.

The problem with filters is that some (nylon type) can be cleaned somewhat... BUT... the "stone like" filters require replacing once they clog. They may look clean but they're still problematic. If it were me, and what I've done in the past, I would bypass the filter completely, rigging a direct fuel supply to the carburetor for a test run.

Let us know what you find.