1999 Johnson 90HP J9OPLEEB Seril#G04660188 Multiple issues

[mako221]

1 issue happened briefly last season. started motor and could not get max rpms. about 1000 under max (5600) took it out to show guy problem and it did not happen, obtained max rpms rest of season. Had boat out 4 times this season. yesterday started motor and could only make rpms to 1000 less then max. For a brief second or 2 it jumped to max then back to 1000 under max???

2 issue Starting is a bit of a challenge. Push and hold key 10 seconds and start. Have to push key numerous times to keep motor running. often times when I put in Gear I need to push key to keep from stalling???
NOTE: RUNS WAY BETTER ON FLUSHERS OPPOSED TO BEING IN THE WATER.

3 issue When running for a time if I pull motor back and into neutral right away, motor will rev up to and some times past 2000 rpms and bounce around/up&down until it settles down. If I pull motor back to ideal in gear for a little bit and then neutral its fine.

Motor has new powerhead 10 years ago and sat for 9 years before I got it 4 years ago from brother inlaw. He put like 10hrs on it before letting it sit.

I had mechanic do compression check, new fuel pump & water pumps and go over. I had carbs rebuilt 2 years ago.

Now nobody I call will work on it. I believe motor has many years left in it if I could just these issues cleared.

It does not take a lot to get beyond my knowledge about working on outboard motors.

Thanks for any ideas

[Bighare2]

I will start with this answer to this question.

2 issue Starting is a bit of a challenge. Push and hold key 10 seconds and start. Have to push key numerous times to keep motor running. often times when I put in Gear I need to push key to keep from stalling???
Your particular engine starts best in a level trim position. The process is to pump the primer bulb till firm. Engage neutral warm up and move throttle to approximately 1/4 or just under that. Turn the key to on, press and hold the key in, turn to start / crank and maintain to hold the key switch pressed in till engine starts. Adjust throttle down a little and press in key if more enrichment is necessary to prevent stalling. As the engine warms up less and less Enrichment is needed. If the engine continues to stall you may need to check the basics of sync and link, idle speed in gear. If the engine is not warming up the thermostats should be checked for operation.

[mako221]

Thanks for the reply. I basically do as you say on start up. I forgot to mention above that motor starts and runs 100% better on flushers opposed to being the water.
Does a Manuel tell one how to do a link and sink? The guy that rebuilt carbs was to do a sink and link when he got a new timing light. Well months went buy and now he don't want to work on it anymore. Motor runs, even idles better when it is warmed up. I was dealing/living with the other issues. With RPM issue it is untenable and I'm afraid it'll let me sitting broke down.
I'm going to try and do what I can. Thanks again

[Bighare2]

There is almost zero back pressure with engine running on the muffs. So yes they can start easier. But if the engine is not breathing well, air / fuel has a much harder of getting into the cylinders. All this assumes the carburetors are functioning without issue.
Due to the age of the engine I would be looking to decarbon the cylinders with EvJo Engine tuner. This stuff works great and is literally ‘Tune up in a can’. Follow instructions on the can. Get the Injector nozzle version so you can inject the juice into the cylinders via the primer solenoid.
Yes the sync and link process is in the service manual.

[mako221]

Thanks I'll look into getting a manuel. The motor has very few hours on a new powerhead. Powerhead was done about 10 years ago and had 10 hours on it before I got it. I ntry it!