Johnson 33HP Super Seahorse

[Xandre]

I have been experiencing problems getting my boat up to what I consider its full speed with a Johnson 33HP Super Seahorse. In the beginning of the seaon I was able to hit about 23-25 MPH and now I am lucky if I am hitting 15-18 MPH. It's not a huge difference but it makes a diff to me.

Recently my boat sannk and the the motor was submerged. I let the motor dry out, replaced the spark plugs and she is alive once again. However she is still running slowly as before the sinking.

Could this be a dirty fuel filter and it is just not recieivng enough fuel? My gas line which pumps the fuel from the external tank to the motor has been replaced and is pumping properly.

Thanks,

-Alex G.
Rochester, NY

 

[Paul Moir]

Re: Johnson 33HP Super Seahorse

How long did you let the motor dry out? You may have lost compression due to rust if you didn't get it running straight away.

Is the boat completely dried out now too? Extra weight will sure slow you down.

Make sure all the throttle linkages are working correctly, so you are actually opening the throttle all the way. The armature plate (the part that rotates with the throttle underneath the flywheel) should hit it's throttle stop and the roller should roll freely on the cam (until it's lifted off by the aux linkage).

If that all seems right, I would go ahead and clean & gap the points, and make sure all the electrical connections under the flywheel are clean and tight.

You can mask out fuel supply problems (clogged filter, weak pump, air leaks) by pumping the primer bulb. If that returns your speed then you may have found your problem. Is the fuel free of water? Did you try dumping the fuel that was in the carb's bowl via the drain screw?

 

[Xandre]

Re: Johnson 33HP Super Seahorse



Thanks for the help. The boat is nice and dry now and I have a feeling the problem is either fuel supply or throttle linkage since this was happening before the boat sank.

As soon as I get out of work I'll be down there checking everything you suggested. Thanks so much!

-Alex

 

[Paul Moir]

Re: Johnson 33HP Super Seahorse

Oh, sorry, I missed that. Forget about that first and second paragraph. Try out those fuel supply problems and see if anything turns up. Something that can give you a clue is to remove the spark plugs and examine their firing ends. The insulators around the electrode of the plug ought to be tan and slightly damp. Variances from that and between the two will tell us a lot.

 

[Xandre]

Re: Johnson 33HP Super Seahorse

So I had the motor running a bit better on Monday. With two people in the boat equaling about 350 lbs I had it running around 17-18 mph. I thought things were looking up but yesterday I took it out with just myself in the boat and I could hardly get it past 5-10 mph!!

When I first hit the throttle the boat starts up as if it is going to take of but then quickly dies out and doesn't get on a plane.

I'm trying to convince myself this is just a fuel problem. The ball pump from the gas tank to the motor doesn't stay very hard but it is no diff than the previous day when the boat was moving along well.

Should that ball be able to pumpo when either end of the hose isNOT connected to the gas tank or motor? Or should it pump only when the pins are pressed down once connected?

Anyone have any ideas here as to why I suddenly am hardly moving along? Doesn't it sound like a fuel problem?

thanks!

-Alex

 

[Paul Moir]

Re: Johnson 33HP Super Seahorse

Usually the bulb will pump up hard if it's not connected to the engine. It should pump up hard when connected to the engine but not running. Once started and consuming gas, the bulb will become 'pumpable' again.
Did you try pumping the primer while the engine was behaving poorly? With that speed loss I would suspect you're loosing a cylinder. Try a spark gap test. Both cylinders' ignition systems should be capable of producing sparks 3/8" long.
Test results must be obtained to accurately diagnose. Diagnosing off symptoms alone is problematic.

 

[Xandre]

Re: Johnson 33HP Super Seahorse

I did try pumping when the motor was running poorly. It didn't seem to have an immediate affect but when I power down then power back up it would take off again then die out again.

What is invlovled in "loosing a cylinder"? I am really not a mechanic by any means and am new to this stuff.

How do I perform a gap test?

thanks for the quick response by the way!! =)

 

[BoatBuoy]

Re: Johnson 33HP Super Seahorse

Xandre, you may have water in the float bowl. Unscrew and remove the high-speed jet and packing nut. Tip engine forward to drain float-bowl.

 

[Paul Moir]

Re: Johnson 33HP Super Seahorse

That's a good idea. There's an even easier way to do it with his engine. Just remove the tiny slotted brass screw from the bottom of the carburetor's bowl, which is on the bottom of the carburetor itself on the small protrusion.

Thank you for trying the primer test. That eliminates fuel restrictions, air leaks, the fuel pump, and the carburetor's float & needle arrangement as possible sources of trouble.

The spark gap test can be done with a spark gap test tool, a cheap plastic tool that lets you adjust an air gap and has connections for the spark plug boot and an alligator clip to clip to the engine block. It normally runs for less than $10 from discount auto tool stores. But you may construct your own easily enough. Just bang two nails into a board about 3/8" apart, then place the spark plug boot on one nail and wire the other nail to the engine block. Connect it to a convenient screw or bolt. Then (with the spark plugs out) give the engine a pull and see if sparks jump between the two nails. Repeat the test for the other boot.

 

[Xandre]

Re: Johnson 33HP Super Seahorse

Would my motor even start, idle and run in reverse properly if this were a spark plug gap problem?

I took the fuel filter apart over the weekend hoping it was clogged and the source of my problem. However, it seems clean to me....just a screen.

I am going to try to get down to the boat tonight after work and check out the gap. I will also make an attempt at checking for water in the float bowl...although taking too much of this thing apart makes me a little nervous.

Thank you once again for the help! My summer is wasting away and I should be out on the water =(

-Alex

 

[Paul Moir]

Re: Johnson 33HP Super Seahorse

The thing about the spark problem is often when you have a weak spark it'll ignite the charge just fine at idle, etc, but fail to ignite the charge every time as the spark advances at higher speeds. It gets more difficult for the spark to jump the gap as the spark advance approches TDC so if it's weak or it can find somewhere else to jump, it will only there.

But I've been assuming all along that when the engine is running slow, it sounds like it is running slow too. It's not reving up higher when it's going slower is it?

The little brass drain screw in the carb is all you have to take out to empty it. It's quite easy. If for some reason it gives you trouble, take the high speed jet or knob off like Boatbouy says. If you've got a choke solenoid for a remote choke switch, the brass slot screw is on the port side of the carb, just above the choke. If there's no solenoid, it's right on the bottom of the carb near the centre. Can't miss it.

 

[Xandre]

Re: Johnson 33HP Super Seahorse

The motor isNOT reving up higher when going at these slow speeds. It just chugs along as if it is only supposed to go that fast(5-8 mph).

I have noticed 2 things this morning when I stopped by the boat.

1. Oil or oily substance coming out of the spark plug holes. Is this normal? Color is dark brown/blacksih

2. More water than I realized is trapped between the floor and the hull. I am going to buy a pump today to try to pump as much of that water out as I can through a hole in the floor. I'm not sure if this is the problem or not because it seems like the engine would be tyring alot harder than it is if it were just loaded down with the wieght of the water.


I see where the drain for the carb is now and will try to drain it out after work, pump out the water and check the gap.

 

[Xandre]

Re: Johnson 33HP Super Seahorse

An Update....

I pumped out alot of water trapped between the floor and the hull of the boat. This gave me maybe 1-2 mph more with just myself in the boat. So all that water wasn't helping but still wasn't the problem.

Tonight I test the gaps but anyone have any ideas on the oil coming out of the spark plug holes?

Thanks!
-Alex

 

[Paul Moir]

Re: Johnson 33HP Super Seahorse

If it's just a little after it's been running a while, it is just because the crush gaskets on the spark plugs are now worn out and leaking a bit. If you're talking about copious amounts with the spark plugs out, you must be running very rich.

 

[Xandre]

Re: Johnson 33HP Super Seahorse

Is there any advantage to setting the gap to a very small setting to be sure it is working?

 

[Xandre]

Re: Johnson 33HP Super Seahorse

OK- I checked the Gap and it seems fine according to what my manual says it should be. I had hope that it was just the gap but I guess not. I'm now leaning towards a throttle linkage problem. What do you think?

I have done the following:

1. Pumped out all excess water
2. Check the gaps
3. Removed the small brass screw on carb and let it drain.
4. Pumped the primer bulb when running slow
5. Took apart fuel filter to check for dirt and build up

 

[Paul Moir]

Re: Johnson 33HP Super Seahorse

You need to test to see if you can make the spark jump a 1/4"-3/8" gap on both cylinders.

How did the firing ends of the spark plugs look? Same?

 

[Xandre]

Re: Johnson 33HP Super Seahorse

To test this do I just set the gap at these different settings and try to start the motor?

If I recall the firing ends looks the same...brownish. I will dbl check today.

 

[Paul Moir]

Re: Johnson 33HP Super Seahorse


The spark gap test can be done with a spark gap test tool, a cheap plastic tool that lets you adjust an air gap and has connections for the spark plug boot and an alligator clip to clip to the engine block. It normally runs for less than $10 from discount auto tool stores. But you may construct your own easily enough. Just bang two nails into a board about 3/8" apart, then place the spark plug boot on one nail and wire the other nail to the engine block. Connect it to a convenient screw or bolt. Then (with the spark plugs out) give the engine a pull and see if sparks jump between the two nails. Repeat the test for the other boot.

 

[Xandre]

Re: Johnson 33HP Super Seahorse

Thank you Paul!

I bought a gap tester but it isn't like what you describe. It was just a metal tool with flat slabs to slip inbetween the gap. I'm sure you know what I am talking about.

I'll see if I can find one of these other tools.