2000 Johnson 150 Ocean Pro Ignition Problem

[polo35m]

Help! I I'm at a total loss on what to do next I've been troubleshooting this engine for 4 weeks now. What started out as what I thought was a simple of carburetion problem has now turned into almost a complete ignition system replacement and still no joy. Engine won't start and idle fine but not get up on plane it would Shake smoke and bog but continue to run. I discovered all 6 carburetors had appreciable cracks in the bowls and we're leaking fuel so I replaced them along with needles seats and gaskets. This made no difference. Then I replaced all spark plugs ...correctly gapped. Checked thermostats opening and closing head temp around 140. Compression on all 6 around 95.
upon the advice of a friend I replaced the power pack and optical sensor. Made absolutely no difference. Since then I have a friend that my Mirena look at the engine this man on his own shop and Marina for over 40 years it is a vro expert. He can repair and diagnose these things with his eyes closed. He double triple checked all my work did a battery of diagnostic tests sat back scratched his head and just said it was inexplicable why this thing is not running correctly.
he suggested that even though the stator ohms out correctly but I should replace it because it has experienced the black goo meltdown phenomena. I have it on order and it will be here Thursday. Any advice thoughts or recommendations would greatly be appreciated. I don't mind pouring money in this engine as I plan on keeping it forever and it is after all 20 years old but I'm running out of parts to replace!

 

[polo35m]

PS. I did forget to mention one of the thermostats when tested in boiling water was sticky and barely opening so I replaced it with a new one this is after all these problems started and that cylinder was running at about 195 so my mechanic friend suggested this could have caused the stator meltdown. Also all connections have been jacked wirebrushed and Dielectric Greased. And finally I have a temporary 6 gallon can hooked up directly to the primer ball with hose filled with nice fresh Rec 90 fuel just to absolutely eliminate the possibility of fuel problem

 

[polo35m]

Very sorry spelling correction:
Engine WILL start and idle fine

 

[Chris1956]

Check the shift assist switch. It kills spark to 1/2 the motor if it is closed.

Disconnect overheat sensors and retest motor. Those also kill spark to 1/2 the motor.

Check diode in wiring harness for same reason.

 

[polo35m]

Thank you so much for the reply! Yes sir I checked the shift interrupter switch and it's working perfectly as well as the temperature sensors. I'm not familiar with the diode in the harness? Where would that be located and how would one check.... for what it's worth the 40-year mechanic that worked on it unplugged the wiring harness from the stator while the engine was running to test if there was something wrong with the ignition switch or harness. And that was not the problem

 

[Chris1956]

The diode is in the wiring harness on the tan wire, between the dashboard and temp sensors. Using a voltmeter on the ohm setting, you should have continuity one way, but not the other, if the diode is good.

 

[polo35m]

Diet appears to be good. Also the mechanic that worked on it unplugged the harness whilist the engine was running at both the power pack end and the tach end which I guess checks to see if that diode is okay and or if it's stuck in quick start.
still no joy. Brand new stator installed, still no joy. New coils coming on Monday will post what happens.

 

[Chris1956]

OK, did you swap the main jets over when you replaced the carb bowls? What size boat and what prop?

Did you clean the throttle bodies? They have an off idle and intermediate mixture responsibility.

Link and synch was done after replacement of ign components?

 

[Chris1956]

Shaking and smoking is sing of bad ign, bad carbs or bad fuel pump. I have never heard of the latter, but I presume it is possible. Did you check the OMS pump for fuel leakage thru the pulse limiter?

 

[Chris1956]

Did you check vapor pump diaphragm? Maybe vapor separator is overflowing and vapor pump is pumping raw fuel into motor? A SWAG (Stupid Wild A$$ Guess)

 

[polo35m]

Thank you for all the replies! A boat is a 21 foot Sea Fox with 150 Ocean Pro don't recall offhand prop size, but will post. As far as main Jets I only replaced bowls needles seats and gaskets the Jets are fixed into the carb body and I did not alter them in any way I only made sure they were clean and clear. I did not clean the throttle bodies however I did remove them because I wanted to inspect the Reed valves and they are intact and appear to be undamaged. Spaghetti seal was intact and not pinched when I reinstalled throttle bodies. I did not perform a Link and synj only because I did not disturb the original setting which was ostensibly perfect because the engine ran absolutely perfect before all this started. I have disconnected and plugged the "choke mechanism" and tested just to eliminate that as a possibility. But I will check the vapor separator and diagram. As far as the vro pump it was rebuilt a year ago and functioning perfectly but just to eliminate that possibility I plugged the oil line and hooked up a 6 gallon tank with fresh nonethanol fuel, fesh fuel line and fresh primer ball....still no difference. Tomorrow the new coils are arriving so I'll see what happens my gut tells me this is an ignition problem.

 

[Faztbullet]

Disconnect all the temp sensors and test. Are you getting a horn alarm? Did you reinstall main jets from old fuel bowsl to new? Is this around the 2500RPM range? If so something is trigger pack into SLOW..either a sensor or bad pack

 

[polo35m]

Oh my God I feel so stupid! I just put the new bowls on I don't believe there were any Jets or anything to remove from the old bowls? Are there Jets down in there? These are the plastic bowls. I replaced the power pack brand new OEM Factory part no difference. And yes it begins to break up around 1800 to mm my mechanic went so far as to disconnect the ignition wire harnrss fom the power pack presumably to rule out the it's stuck in any kind of slow mode we also disconnected both temperature sensors and make no difference.

 

[polo35m]

Oh my God! After a month and $1,250 you have just solved my problem! I feel so stupid. I see in the parts diagram there is the high-speed orifice and I threw my old bowls away. Part number 15. I just can't believe it I will order new ones today. Thank you!