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'94 48 SPL, runs great, takes forever to start

H

halbrodmann

Contributing Member
My son and I recently brought an old Johnson motor back to life. Link and sync seems to be correct, but in order to get the idle down to a reasonable level, the timing is set at about 3 ATDC. Again, the motor runs great once it's started, but starting it is a nightmare. My son feels that the motor has a better chance of starting when it's out of the water. Obviously, these old motors don't have a throttle adjustment screw, so adjusting the idle timing is usually the way to adjust idle speed. Do I need to set the timing differently and deal with the high idle RPM's? Any other ideas would be greatly appreciated. I hate to just start making random adjustments when the motor is running so wall at all speeds, but taking forever to start isn't much fun either. It almost completely drains the battery getting it started. It cranks up great when in the muffs in the front yard. I don't think its a ground, or electrical problem because it runs so well once it cranks up.
Thanks in advance for your help.
 
Is he advancing throttle on cold start?----Is he pushing in the key and holding it in while cranking it over?-----And with all this cranking it is now time to take the starter apart for inspection , ohm check on armature.----And have the battery load tested.
 
He has a "newer" model control box with fast idle. He is using the primer when cranking. I'm not sure if the fast idle is moving enough to advance the timing though. I'll probably set the timing to TDC and see how that works. I'd much rather deal with a high idle that have all of the cranking issues. Obviously, unless the idle is so high that it may cause lower end issues when going into gear.
 
The motor should start right up if the right procedure is used.---Sorry----I can not see how this motor is started from here.
 
I understand. Is there a Manufacturer's spec for idle timing on this motor? I've found 2 websites that give a timing spec for idle timing on the motor. One says 3 Degrees BTDC, and the other said 3 degrees ATDC. I came to this site hoping you would see this, because I figured you would know the ideal idle timing off the top of your head. Any recommendations would be greatly appreciated.
 
Maximum timing advance is set.-----Idle timing is where throttle plates OPEN----where the motor idles smoothly looks after itself.---Actual timing at idle does not matter.
 
Thanks for your reply. I don't understand any of what you said, but I appreciate your attempt to help. There are adjustable rods between timing plate and the cam that opens carb plates. So, I can adjust timing all over the place and set the rod at the point where carb plates open. I'm sorry, but it's not as simple as you seem to be stating. Looking through manuals, I'm finding all kinds of conflicting information on the lengths to adjust the rods and I'm just getting more and more confused with what starting point should be.
Thanks for your time. I'll figure it all out somehow.
 
Idle timing is not the same concept as on an old 283 Chevy !----Timing on these motors normally does not go out of adjustment.-----Be careful with this motor.----Good trouble shooting will find the issues.----Test operation of the primer valve.----Post actual compression values here..----Check fuel pump diaphragm.----Check flywheel key.-----Load test the battery.-----Take starter apart for inspection and ohm check on armature.
 
I have been plagued with the same starting issue on my 1987 48hp for last 3 years. I feel like it's a choke or fuel line leak but can't figure it out. I replaced the solenoid, rebuilt carb, had mechanic look at but it can't be replicated out of water.
 
Update. Sorry to revive an old post, but I thought the history here would help in diagnosing the problem. Motor is running great now. Fires right up and idles smoothly and opens up and runs great at top end speed. But. The last time he had it out it let him down. We met over at a beach and spent the day. Boat ran fine getting him there. Boat ran fine running around a bit. We headed back to the dock to take boats out and the wind had died down a bit, so we were able to run at full throttle most of the way back. Made it back to the dock fine, got in out trucks and went to take the boats out of the water. His boat would not start. No spark. Though obviously the trip to the beach and the trip back were the same distance, the only difference was that most of the way back we were running faster. We drained the battery trying to start his boat. We sprayed carb cleaner (as started fluid) directly into the carbs and still didn't fire up, so we can only assume it was a non-firing issue. He had plenty of gas, bulb was pumped up and tight, and battery was strong and spinning the motor well when he started trying to crank it. We got his boat on the trailer and got it home. A few days later, just out of curiosity I pumped up the gas, turned the key and it fired right up. So, what would you experts suggest to test first?
Could it be a weak ignition component that heated up to the point of failure - like a coil? Would testing coils indicate a coil that was somewhat bad and would stop working if overheated? I'm anxious for him to get back in the water in this boat and his wife is losing confidence in taking this boat out with a 3 year old and an 8 month old. Yeah, we've probably all been there before. Boats having issues is all part of it for us, but for wives, it's not an "adventure", it's a disaster when things go wrong!
Thanks for any suggestions you might have.
Be careful out there! Freedom Boat Club will put anyone behind the wheel!
 
Check the charging system on the motor.----Have battery load tested.----Some will argue, but take starter apart for inspection / cleaning / ohm test on armature and perhaps new brushes.
 
It's spinning fine, but no fire. Again, 2 days later, it started right up at my house. No charger on battery or anything touched on the motor.
 
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