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Update 1993 Johnson 150 Morten

S

sparkie_212

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"Morten,
And anyone else

"Morten,
And anyone else that has been following this engine problem. To continue some general maintenance I removed all 6 carburetors and inspected them inside and out, and the main reason was to make sure all screws were tightened to torque specs. I double checked my sync and link and found an error I had made right at the very end of my last sync and link which explains the high idle I was getting: You need to disconnect the throttle cable during this proceedure. When I went to put it back I noticed that when my throttle cable was in the full throttle position it did not match the linkage in its full throttle position. So I adjusted the spindle on the throttle cable to make them match. What I didn't realize was that where I took some out in full range it did not let it release all the way in idle position, so it was allowing the spark lever roller to touch the spark cam, which caused the higher idle. I still am wondering why all the hard starting and hard to keep it idling was all about though. But it runs great now with the muffs.

I did check something that you had mentioned. After running the engine for at least 10 minutes with several minutes of reving the engine up on occasion, after that 10 minutes I felt the top of the heads. The 1-3-5 head was hot to the touch no more than 2-3 seconds and was burning. But the 2-4-6 head was not that hot. I could hold my hand on it for as long as I wanted, but it was warm. Is the cold side telling me I have a bad thermostat?

Not sure if this will cure the motor so plan on taking it to the lake to run it and check for problems. But I am wondering if I should run it hard before checking the thermostat?

Also reconnected the tach and with all adjustments made I adjusted it so that the idle was reading 800-900 rpm. I hope that is correct because I do not know of anyway to calibrate a tach."
 
"You better get the thermostat

"You better get the thermostat(s) changed, or you will get idling problem, sneezing, and the screws gets loose again! Thermostats that are stuck open will not go back and close!
The tach setting seems to be correct, the difference if wrongly adjusted is rather big.
Good luck on the test!"
 
if you adjusted idle that low

if you adjusted idle that low out of the water when you put it in and put it in gear it will most likely die. 1200 to 1500 outof the water
 
"I didn't actually adjust

"I didn't actually adjust the idle that low, I adjusted the tach to that area, 800-900 rpm. It has a little screw in the back for calibration. Do you know how I can calibrate it correctly? I made the Idle Timing and Maximum Spark Advance dead nuts as to the specs in the sync & link in the book with an ignition analyzer. The book states the engine should range from 600-700 rpm in gear at idle, depending on propeller selection. So I am thinking that next trip out if everything is working better which I believe it will, I will adjust the tach to this 600-700 rpm in gear at idle. I found another problem tonight. The Timer Base is pulled back into position with a spring. The spring on this motor was "sprung". It was not taking it back to the stop on the flywheel cover. I cut out at least 3 if not more coils of the spring in increments until It completely pulled it back into position. I think this will make a big difference too. The book says when you make the Spark/Throttle Pickup Point adjustment it is very important that the timer base and carburator linkage start to move as you give it throttle at EXACTLY the same time. I noticed tonight the carberator linkage was moving just a little before the timer base was and knew I had just made that adjustment. So a closer look and I found out why. With the spark cam not pulling back all the way it was lagging behind as the throttle was engaged. Also would explain a small rise in the rpms, not much but every little misadjustment ads up."
 
"First this engine does not ha

"First this engine does not have a timer base, what is mooving is an infra red light bulb, an optical sensor! What is important as You have noticed is that it moves freely and to the end stop. Be carefull with what you lubricate this with. If You spray with WD40 or similar you may ruin the optical sensor! (Like spraying wd 40 on a light bulb). Take it off and use thin silicone grease. As for adjustment the carbs must not open before the timing dvance starts, the engine may stall/hessitate. The idle adjustment is actually done only by advancing/retading the timing, not by opening the carbs. Put the boat in water for the final adjustment, remember it should be in gear and moove freely! If it runs smooth at low idle You will have no problem setting the tach accordingly.
PS: Haveing an optical sensor as spare is quite a good idea. I have changed quite a lot in my time, they pop like light bulbs and the engine is totally dead!"
 
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