1964 3hp Johnson Help Needed

[U076762]

Greetings,
I have rebulit the carb and water pump for a friend on the JH19A and am having problems keeping it running. I am not sure when it last ran. I would appreciate some expert help.

I can get it to start, runs irregularly for 10 to 30 seconds and then slows and stops. Wait a few seconds and I can repeat.

1. Compression is 60 psi on both cylinders, well below the 100 psi min. Cylinder walls looked good, but I could not find replacement rings. Would low compression cause a limited run time or just poor performance? Any source for aftermarket rings (tried Sierra)?

2. I could not remove the metal fuel filter internal to the gas tank. I cleaned it as best as I could, but suspect that perhaps that it is still restricting fuel enough to cause the limited run time. Any suggestion on how to remove the filter without breaking it?

3. Any other suggestions?

Thanks,
Bill

 

[F_R]

Re: 1964 3hp Johnson Help Needed

The filter is highly suspect. Once dirty, they are next to impossible to clean. You are supposed to just replace the whole thing, fitting and filter combined. However, I unsolder the filter and solder in a piece of rolled-up brass filter screen. Much cheaper and cleanable.

 

[U076762]

Re: 1964 3hp Johnson Help Needed

F_R,
Is the metal filter soldered in place? If so, that explains why I could not get it out with solvent and "gentle persuasion". I like the brass screen idea since a new unit is $46.00. Any tips on filter removal would be greatly appreciated.

Thanks,
Bill

 

[tx1961whaler]

Re: 1964 3hp Johnson Help Needed

The metal filter is soldered in place. You can easily tell if it's clogged by unscrewing the fuel line and opening up the petcock with a container under it. If it's clogged, there will be barely a trickle coming out of it. I would not worry about the compression if the readings are within 10 psi between the cylinders. I just finished rebuilding my 1958 Evinrude 3 hp today. It had sat outside under a tarp for 10+ years at my parent's house in FL and had nothing that wasn't frozen up on it. It took alot of time, compressed air, many solvents, and swearing, but everything finally came free. The only new parts that I had to put on it were points and condensers, new packing on the needle valves, an impeller, and a new rope for the starter. It started on the 3rd pull. I love these old engines!

 

[U076762]

Re: 1964 3hp Johnson Help Needed

Greetings,
Thank you both for the tips! I will update after attacking the filter.
Best Regards,
Bill

 

[samo_ott]

Re: 1964 3hp Johnson Help Needed

The other option of course is to get rid of the old filter and install a new cheap inline plastic filter.

 

[U076762]

Re: 1964 3hp Johnson Help Needed

Greetings,
I took off the gas tank and opened the needle valve over a gas can. It flowed easily at full stream. That eliminates a filter obstruction.

I saw an older post that identified an obstruction in a reed valve as a problem. Should I completely disassemble the engine and make new gaskets assuming a crankcase vacuum leak? Any other ideas?

I appreciate the help.

Bill

 

[F_R]

Re: 1964 3hp Johnson Help Needed

That would be pretty drastic without a lot more reason to suspect that it was necessary. Reeds never give any trouble unless critters have crawled in there and made a home.

How about a sticky or out of adjustment float? How about a gummed high speed jet orfice plug?

How about buying a carb kit and do a thorough carb cleaning?

 

[U076762]

Re: 1964 3hp Johnson Help Needed

Hi F_R,
I had rebuilt the carb, but it sure seems to be fuel related. I will tear it down again and recheck. I also will try a soap solution spray on the outside of the gearcase and look for pressure leaks (per Clymer manual). Will report back in a few days.

I appreciate your help.

Bill

 

[U076762]

Re: 1964 3hp Johnson Help Needed

The saga continues,
I removed the carburetor and it appears that the wire connecting the needle to the float had come loose (although I can't guarantee it didn't come off during disassembly). I also removed the reed valves and cut replacement gaskets.

I removed the powerhead from the tube and the lower exhaust section. I cut replacement gaskets for these as well. Replaced all using Gasket Sealing Compound. Note: I saw a few drops of water weep through these powerhead gaskets. I used gasket stock from auto store; I suspect that there is a marine gasket I should have used. Any recommendations or comment?

The engine started and I could get it to run for extended periods with the speed lever just above "Start" ~3000 rpm. It would die if I went to full. Low speed about 2000 rpm. Partial choke could get almost 5000 rpm (a few seconds as I know WOT is 4000 rpm). Not sure what else to do?

I appreciate any help.

Thanks,
Bill

 

[F_R]

Re: 1964 3hp Johnson Help Needed

I can't remember--did the 1964 have both a high speed needle and a slow speed needle? If just the slow speed one exists, then there is a fixed high speed jet. It sure sounds like it is gummed. Are you SURE you cleaned it? Even a micro-coating of varnish in it will make it require choking to run. The fixed jet is located deep in the hole behind the hex headed drain screw, and requires a special screwdriver to get it out.

 

[U076762]

Re: 1964 3hp Johnson Help Needed

Greetings,
The high speed jet is fixed. I had removed it initially. This time I sprayed lots of carb cleaner only and did not remove it. I can easily do this again. Remember that I only had about 60 psi compression in each cylinder.

I also watched the spark using a nice inline tester on each cylinder and verified that it was strong.

Any comment on the gasket stock used and whether there is any downside to a carfully applied coating of Gasket Sealing Compound?

Thanks,
Bill

 

[F_R]

Re: 1964 3hp Johnson Help Needed

I find no fault in the gasket material, but would not use any goop on the reed plate or manifold gaskets that may foul the oil return holes or get under a reed.

 

[U076762]

Re: 1964 3hp Johnson Help Needed

Greetings,
Per F_R's recommendation I disassembled the carb again and made sure all passages were cleaned, especially the high speed nozzle.

The engine started easily and was able to go to full speed. Now the question that shows my ignorance.

I measured the rpm with a wireless tachometer on one cylinder (I use this tach for single cylinder lawnmower engines). I measured 8000 rpm at full and ~1800 at the lowest I could run. Is the manual specification of 4000 WOT based on measuring a single cylinder as I did, divide by the number of cylinders, or is the gear ratio take into account since 8000/2 is right on the money and I really don't have any adjustability that I can see. If I should have measured 4000 rpm at max on a single cylinder, what should I do?

Another embarrassing question regarding the gas cap. The rubber seal under the vent screw needs to be replaced. I tried simply unscrewing it and the inner part where the bead chain attached distorted to the point where I stopped so I would not ruin it. What am I missing?

Best Regards,
Bill

 

[U076762]

Re: 1964 3hp Johnson Help Needed

Greetings,
A friend suggested that perhaps the wireless tach is picking up the signal from both cylinders and giving a false double reading. I will try some foil between to perhaps shield the second cylinder's signal. I suspect that is true.

Thanks