63 Johnson 3HP Engines dies out after running several minutes

[jackiebpratt]

Hello all. I have a 'new' 63 Johnson 3HP. Seems to run relatively smoothly, and starts easy enough. Feels like there is decent compression. Water is spitting out the coolant exhaust. Using 30W Non-Det at 24:1 as per some other posts here.
1st Question: After running for several minutes (maybe about 5-10) motor dies. Will start back up, but then will only run choked or half choked. It had been sitting for a while before I got it. My guess is dirt in the gas, and that it clogs the filter or bowl/carb after running a little. I look to tear it down this week sometime and clean out the fuel lines/system.
Second Question: Although the exhaust is spitting out some water, it isn't a steady squirt, but is much more 'airy' then watery. I am thinking that maybe the impeller is worn. Or does the exhaust mostly blow air not water?
What do the experts say? Thanks and good boating.

 

[muskrat]

Re: 63 Johnson 3HP Engines dies out after running several minutes

I would check the impeller first.I had a 1960 3hp that would pump ok but heat up and quit after running for 5 or 10 minutes.The impeller had been run dry.

 

[F_R]

Re: 63 Johnson 3HP Engines dies out after running several minutes

Spitting a spray of water droplets out the exhaust relief is normal operation. It does not squirt a steady stream. However, don't take on a false sense of security--the spray only means it is working NOW. It does not mean the impeller won't fly apart five minutes from now. The only security is to know that you have a good fresh impeller in there.

Now for the problem: Since you say it is spraying water, let's assume the cooling is ok. So, chances are about 90% that the sintered fuel filter in the gas tank is partially clogged. It is allowing gas to go through but not as fast as it is burned, so at some point it runs out of gas and quits till it fills up again. This is assuming (there we go again) that the tank vent is open and not clogged.

The sintered filters are next to impossible to clean and should simply be replaced.

The other 10% chance is that the carburetor is gummed up from sitting. Or both, which amounts to almost 100%. There is also the chance that it is not fuel related at all.