sportwin won't make full power

ezeke

Supreme Mariner
Joined
Sep 19, 2003
Messages
12,532
Re: sportwin won't make full power

Look at that high speed orifice in this way: it provides the control on the quantity of fuel where you are having a problem. The fuel moves up from there to the top of the carburetor, then down through the reeds to the combustion chambers.

The fuel pump keeps the float bowl full, but the movement of the pistons actually pulls the fuel through the reeds.

To clean the high speed capillary and the jet without a complete carburetor rebuild, you could force carburetor cleaner through the jet from the bottom by using the pipe that normally comes with the Gumout inserted tightly against the jet.

Then, if you look carefully at the base of the choke bowl on the top of the carburetor, you will discover a small hole facing from the starboard that leads back to the high speed jet in the other direction. If you insert your Gumout pipe there and blow the cleaner in that direction, you will have cleared any major obstruction.

You can then replace the float bowl drain plug and test.

If that gives even modest improvement, I would rebuild the carb.


I know that everyone would like to see an easy solution to the problem that you have. The bottom line is that the compression test is one of the finest diagnostic tools.
 

xort

Seaman Apprentice
Joined
Sep 24, 2006
Messages
46
Re: sportwin won't make full power...SOLUTION

Re: sportwin won't make full power...SOLUTION

The solution was WAY too obvious.

I was talking with my big boat mechanic about the problem. He asked if the primer bulb was hard. I never thought to check, it was hard when I started it.

Well, I had an old 6 gallon steel tank. It was pretty heavy so I bought a new lightweight plastic 3 gallon tank from Bass Pro Shops. I just switched back to the old steel tank and I can plane off in 2 seconds!!!
When I first used the new tank it did work fine so I suspect it has developed an air leak in the connection fitting.

Wonder if I can get a refund?

Thanks all for the help.

One lesson learned is that these old engines run great with only 60 lbs compression.
 

xort

Seaman Apprentice
Joined
Sep 24, 2006
Messages
46
Re: sportwin won't make full power

Went in to my local small boat service place this afternoon. The guy has been servicing Evenrudes for 20+ years. He told me 60 PSI is normal for compression on those older small engines.
 
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