Unusual problem on a 5.5hp Johnson 1960

[cajuncook1]

quote joesnuffy:

Compression seems really good. I also put new plug wires on the engine and it will run very slow especially with the electronic modules it actually has a hard time stopping it idles down so low. The motor also had this problem with the points and condensers installed I forgot to mention that.

Joe

Joe your inital hard starting maybe the carburetor or the fuel pump. You stated the compression feels really good, but have you actually tested the compression of both cylinders with a compression gauge?

If your ignition is in good shape and you rule out fuel delivery issue (carb or fuel pump) then the compression maybe an issue. Please get a reading of the top and bottom cylinder with a compression gauge. That way you have ruled out compression as an issue. Remember compression, spark, and fuel (CSF). Issues with one of these will cause running or starting issues.

Lower compression motors are hard to start, but once started they run ok. Low compression motor do not pull in enough fuel mix(fuel charge) into the cylinders from the crankcase. So, it takes longer or multiple multiple starting attempts to get started. Once there is enough fuel charge in the cylinders, the motor will start. Now the motor is running it increases rpms and increases compression some and the transfer of fuel mix (fuel charge) from the crankcase to the cylinder heads becomes easier.

Let us know your compression numbers. If you do not have a compression gauge, then you get one at Auto Zone, OReillys….etc etc. Some will loan you one with a return deposit.

Cajun

[cajuncook1]

Oh, an after thought. Do you still have the glass bowel with sinter porous filter in line? If the sinter filter is still in line and somewhat occluded, then that can cause a fuel delivery issue. Even though it looks clean, it may be partially occluded with old varnish. Soak it in a bowl of warm/hot water that is half mixed with Pinesol. After a couple of hours, use an air compressor to blow clear the filter and watch how much gunk comes out. Do not use carburetor cleaner or it will turn into a pile of sand.

[fleetwin]

Just want to be sure I understand…Do you use the choke at all when attempting to start cold?
Are you sure this is a 1960 model, the 59s used the pressure tank system…

[joesnuffy]

Thanks everyone this really saved me some time. It turned out to be the fuel diaphragm. It had a hole in it. I did as suggested and pulled the fuel pump off the motor and pumped up the fuel bulb and fuel came out the impulse hole like crazy. The motor started first pull with it removed cold after I pumped up the fuel bulb. I did put a new fuel filter on the motor the hard ceramic filter because it was missing when I got the motor so it is pretty much good to go now with new coils, ignition modules, new rope, new impeller, new base gasket, new starter rope etc. It’s a terrific motor and very easy to work on which is one thing I like about it. I now will have to make a new fuel diaphragm for it which I have made a few in the past.

Thanks Everyone,
Joe 😀

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