1989 johnson gt 150 intermitant miss or skip between idle and 2200 rpms

[69stingray]

Good evening all:

I am new to the outboard arena. I recently bought a boat with a 1989 johnson gt 150 crossflow motor. After replacing
all 6 coil packs (Sierra) and thoroughly cleaning the carbs and synchronizing butterflies, I got it running on my test tank. I have since:

replaced plugs, wires, all fuel lines, bulb and filters, gear oil, thermostats, and water pump, and powerpack (Sierra)

Between idle and 2200 rpm, I still have an intermittant miss or skip. 2200 to 5500 rpms, she runs like a champ.

Any guidance, direction or solutions would be greatly appreciated.

Thank you in advance,

John

 

[emdsapmgr]

Re: 1989 johnson gt 150 intermitant miss or skip between idle and 2200 rpms

When you cleaned the carbs, did you remove all 6 jets from each carb and visually inspect them for restrictions? You made no mention of whether the miss was different when the engine was cold or when fully warmed up. You might want to check the voltage output from the stator. It needs to be at least 200 volts at normal cranking rpm's. As measured with a special "peak-reading" voltmeter. That engine has the magnets epoxied/glued into the inside of the flywheel. Make sure none of them are loose.

 

[69stingray]

Re: 1989 johnson gt 150 intermitant miss or skip between idle and 2200 rpms

I did remove all six jets cleaned and installed new factory kits with new floats. This was the second cleaning didnt install
new kits the first time. It didnt have much effect on the condition. Hot or cold doesnt seem to change it much, but it may be slightly worse when hot. All magnets are in place and tight. I have not bought a peak voltage adapter yet. I attempted
to use the reeves timing method this afternoon. I got a reading of 33 degrees at WOT turning over, plugs removed in neutral. This is way high because 28 degrees btdc is factory recommended setting. It was a long way from 24 degrees per Reeves. Did I do this correctly? What should the timing be at idle? What is the proper idle rpm for the 89 gt 150? My problem is still between idle and 2200 rpms. Could my fuel pump be causing it?

Once again Thanks for all the help

John

 

[emdsapmgr]

Re: 1989 johnson gt 150 intermitant miss or skip between idle and 2200 rpms

You would probably set the idle timing initially around 6 degrees. Put the boat in the water, start it and shift into forward. You will then re-adjust/reset the idle timing so that the engine will idle at 650-700 rpm's. You must set the idle timing by rpm's. The actual (final) idle timing by degrees is of no real consequence. Idle rpm's will vary from one engine to the next, depending on the boat. Each will be idle timed differently due to the depth the engine sits on the boat when floating- in gear. Usually a weak fuel pump will affect all 3 carbs. Insufficient fuel at high rpm's will cause all 6 plugs to starve for fuel-the boat will usually slow down. A high speed miss is usually not attributed to a bad/weak fuel pump. Just in case, you can test for a weak fuel pump. When running over 2200 rpm's, have a friend constantly prime the fuel hose bulb. This will force extra fuel into the carbs. If the engine pics up and runs fine at WOT while constantly priming the fuel hose bulb, then you have a fuel delivery problem. (Weak fuel pump, defective fuel tank pickup, defective anti-siphon valve.) That engine does have Quickstart. That feature will affect idle timing untill the engine heats up to 96 degrees. When starting a cold engine with quickstart, the power pack will advance the timing 4-5 degrees to help the engine run better when cold. You may need to compensate for this timing offset on a cold engine when setting the WOT timing. Usually, Quickstart will cancel itself once the engine revs to over 1100 rpm's or warms up to 96 degrees. Since you are setting timing when the engine is cold and not running, that may or may not affect the Quickstart timing advance feature. You'll need a factory serviced manual in order to set the WOT properly using the Reeves method. Your setting of 33 degrees may not be far off if setting it on a cold engine-non running engine. Those 150 XP/GT models in that year came from the factory with a 28 degree max timing. That would be set at close to 5000 rpms-when the engine is heated up to normal operating temps. If you use the Reeves method (which works just fine) you would probably want to set max timing at 24-again, after the engine is fully warmed up and Quickstart is not active. I think you should continue to attempt to test your stator voltage output when cranking.

 

[Faztbullet]

Re: 1989 johnson gt 150 intermitant miss or skip between idle and 2200 rpms

Sounds like a "t-pack" acting up as these are know for quirks, If you call CDI and talk to Clark they will suggest you replace timer base an pack. If you can make it happen at rpm on the trailer in water , take a timing light and check cylinder and you will see the miss. Check all connections and disconnect yellow wires to rectifier and test.

 

[69stingray]

Re: 1989 johnson gt 150 intermitant miss or skip between idle and 2200 rpms

Good evening all:

FYI: I followed a hunch that I had. I pulled off all of the recirc. check valves on my intake when I could not find
an intake leak with carb cleaner or an open propane valve in front of my carbs. All six of my check valves were
defective. This appears to have been my problem. It ran the smoothest ever on the hose. No miss or occasional lean sneeze. I have not water tested it yet but this is a was a major improvement.
Where is the best place to purchase a factory service manuel or prefereable a CD?

Once again I would like to express my appreciation for all the help.

Thanks,

John

PS Will report water test results.

 

[emdsapmgr]

Re: 1989 johnson gt 150 intermitant miss or skip between idle and 2200 rpms

Ken Cook Co., in Milwaukee sells all of the original factory publications. You can contact them on their website: outboardbooks.com

 

[69stingray]

Re: 1989 johnson gt 150 intermitant miss or skip between idle and 2200 rpms

Good Evening All:

Is there a way to temporarily disable the quickstart feature on a 1989 GT 150 Johnson? Once again

Thanks In Advance,

John