1970 Johnson 115 at my wits end

[farmuse]

OK I need help. Someone on this board is bound to know what I am overlooking. I have a 1970 Johnson 115 electric shift with 13 1/4 x 17 prop. It is on a 1976 Starcraft cheiftan cuddy cabin. I will first tell you what I have done and then tell you what the problem is.

Remove carb and clean making sure all passages are clean.
New wires, plugs, stator (because it was not charging now it does)
Check compression has 116-120 on all four.
Adjusted linkage and distributor/timing according to factory manual. I think yall call this linc and sync.
New fuel lines from tank to engine including lines on engine.
New water fuel separator.
New Plastic fuel tank
Check spark on all four cylinders

Now the problem I am having:
Starts and Idles well but when I try to get the boat to plane there is just no power the engine does not falter when I shoot the throttle to it and I can push the throttle to the wide open position it acts like i still got the trailer attached to it. :grumpy:


I am an hour from any water but I have a big cattle stock tank i can put the engine in just like I am in the water. I can't get it over 2500 RPM. If anyone has an idea as to what I am overlooking I would appreciate it if you would speak up

Thanks:grumpy:

 

[JB]

Re: 1970 Johnson 115 at my wits end

Check for cylinders not making power by removing spark plug leads. Continued rpm means that cylinder is not making power. Drop in rpm means making power.

Side by side cylinders not making power = carb.

Over-under cylinders not making power = power pack.

Also check prop for spun.

 

[boobie]

Re: 1970 Johnson 115 at my wits end

Agree + 1 ...........

 

[jbch]

Re: 1970 Johnson 115 at my wits end

Wow, I have the exact same problem with my 1972 Johnson 100HP. It sat for 17 years, and I dug it out and cleaned it up. I had to put a new CDI power pack, coil and rectifier on it. I've cleaned and adjusted the carbs a dozen times, mine have no adjustment other than the floats. It will start and run good in the tub of water, but on the lake it won't accelerate to push the boat on plane, it bogs down. I recently adjusted the sensor under the flywheel to .020 rather than .028 and it think it starts better. I have an inductive timing light that shows good fire on all cylinders up to a certain RPM then anything above that causes erratic misfire, bring the RPM down a touch and it smooths out. I haven't replaced the distributor or rotor, but I have cleaned and used emery cloth to shine up the brass. There is a little pitting from use years ago, but I don't think that would cause the problem. I talked to a CDI technician yesterday to get their input and he couldn't imagine a sensor failing, as its just a tiny coil of wire that sense the rotor passing by, but I thought it might have gotten moisture in it and weakened it. Him and his other techs, were pretty stumped and didn't have a clear solution. They are having me send in my pack, coil, and OEM sensor to do diagnostics on it. I really believe this has to be the problem, but I didn't want to spend the 150+ for a new sensor to find out it wasn't the problem. The old one passes the bench test of ohms and obviously works enough to get it started and running.

If you track down the problem, please post the solution as this has puzzled me for the last two years.

Thanks again.

 

[JB]

Re: 1970 Johnson 115 at my wits end

jbch, it is not polite to hijack another person's thread. Start your own thread.

 

[Fishknutz]

Re: 1970 Johnson 115 at my wits end

My Johnson 115 did the same thing. My fix was to take the wires from the power pack where they connect to the coil, cut them back about 3 inches and reconnect them to the coil. Those connectors will oxidize over time not allowing enough power to the coil.