1987 50hp johnson

[woodducker]

Ran my boat this past weekend and ended up being towed in. This motor has always had issues of being cold natured but it started and i ran it for about 10 minutes to my fishing hole. Went to move to another spot and i ended up killing the battery trying to start it again. My brother took it out a couple of weeks ago and it did the same thing. The carbs have been cleaned. Just wondering if maybe i missed some adjustment somewhere. Its alot different than my 25hp rude. Thanks!

 

[Joe Reeves]

Re: 1987 50hp johnson

Starting procedure.... Pump fuel bulb up hard, apply a slight bit of throttle, crank engine and push the key in to activate the fuel primer solenoid. If all is well, that engine should fire up and run within six revolutions.

Check compression. What are the readings?

With the spark plugs removed, the spark should jump a 7/16" gap with a strong blue lightning like flame.... a real SNAP! Does it?

If no spark OR weak spark.... disconnect the large RED electrical connector at the engine, then recheck the spark by jumping the starter solenoid (small jumper from battery terminal of solenoid to small 3/8" nut terminal.

Let us know what you find.

Look closely under the flywheel at the stator. If there's a substance leaking, dripping down on the timer base and powerhead, replace the stator.

 

[Boss Hawg]

Re: 1987 50hp johnson

Starting procedure.... Pump fuel bulb up hard, apply a slight bit of throttle, crank engine and push the key in to activate the fuel primer solenoid. If all is well, that engine should fire up and run within six revolutions.

Check compression. What are the readings?

With the spark plugs removed, the spark should jump a 7/16" gap with a strong blue lightning like flame.... a real SNAP! Does it?

If no spark OR weak spark.... disconnect the large RED electrical connector at the engine, then recheck the spark by jumping the starter solenoid (small jumper from battery terminal of solenoid to small 3/8" nut terminal.

Let us know what you find.

Look closely under the flywheel at the stator. If there's a substance leaking, dripping down on the timer base and powerhead, replace the stator.

Right on the money advice
But the part you stated about cleaning the carbs Best to rebuild them You'll have to do it sooner or later

 

[woodducker]

Re: 1987 50hp johnson

hey thanks. I checked compression at 110 on both cylinders. I have good spark. There is nothing leaking under the flywell looks good. i again removed the carbs and soaked them over night. installed and still unabled to start. Fuel pump is working. But i do have a question on the lean rich of the fuel. is the red lever on the side control that? other than that im still stumped.

 

[Joe Reeves]

Re: 1987 50hp johnson

The jets on those carburetors are fixed..... no rich/lean adjustments. You'r mention of the red lever may be your problem, expalined below.

(Fuel Primer Solenoid Function)
(J. Reeves)

The RED lever...... The normal operating/running position is to have that red lever positioned over top of the solenoid and aimed at the other end of the solenoid, gently turned to its stop. This is the normal/automatic mode position. Pushing the key in opens the valve within the solenoid allowing fuel to pass thru it in order to prime and start the engine. Looking upon this solenoid as a electric choke results in a better understanding of it.

Having that red lever turned in the opposite direction, facing away from the solenoid, allows fuel to flow thru it to the crankcase area. One would only turn the red lever to this position in a case where the battery might go dead and the engine had to be started via the rope pull method. Look upon putting the red lever in this position as moving a choke lever on a choke equipped engine to the full closed position. Either one would supply fuel to the crankcase/engine for starting purposes BUT if left in that position while running would flood the engine.

The later model primer solenoids are equipped with a schrader valve, used for attaching a pressurized can of fogging oil etc, available at your local dealership with complete instructions.

Pumping the fuel primer bulb up hard fills the carburetor float chambers of course, but that process also applies fuel pressure to the primer solenoid.

The two small hoses leading from the primer solenoid branch off via tees to each fuel manifold section that would feed fuel to the individual cylinders.

Pushing the key in activates the primer solenoid to allow fuel to flow thru it to the intake manifold passageways. Cranking the engine over causes the fuel pump to engage which in turn sends fuel pulses to the primer solenoid via the 3/8" fuel hose.

Some engines incorporates the "Fast Start" feature which automatically advances the spark electronically so no advance of the throttle is required for starting.
Engines that do not have the "Fast Start" feature will be required to have the throttle advanced slightly.

Starting procedure: pump fuel bulb up hard, crank engine and push the key in at the same time. When the engine fires/starts, release the key so that it falls back to the run position.

Bottom line..... Look upon the primer solenoid as an electric choke.

 

[woodducker]

Re: 1987 50hp johnson

Thanks i always wondered about that. I was able to run it this evening with pre mix in a bottle to start the motor. it ran good but will not start without the spray thru the breather box. Do you think it is a adjustment problem or do i need to get rebuild kits for the carbs? I may need a new ignition switch as well it wants to not do anything when i push in the key and crank.

 

[Joe Reeves]

Re: 1987 50hp johnson

Remove the large screw from the float chamber to see if fuel is indeed entering those chambers. If not, the float needle valves are sticking shut OR no fuel is being applied to the hoses leading to the carburetors.

If fuel exists at that point, remove, clean, and rebuild those carburetors using new complete kits. Kits available at this siter, NAPA, Sierra, any dealership, marine stores, etc.

 

[woodducker]

Re: 1987 50hp johnson

I rebuilt both carbs. and made sure my tank was vented. And i still am unable to start the motor without some premix sprayed thru the carb box. it will run fine. but when i stop for a 10 minutes or so it will not start untill sprayed again. Where should i look now? The primer?

 

[Joe Reeves]

Re: 1987 50hp johnson

Pump the fuel primer bulb up hard. Now, remove the front lower screw from the face of the carburetor float chambers to see if fuel has actually entered the float chambers.

If fuel exists within the carburetor float chambers, you're overlooking something in the carburetors. Remove, clean, and rebuild them, using complete carburetor kits. Kits available on this site, any dealership, NAPA, Sierra, marine type stores, etc.

 

[woodducker]

Re: 1987 50hp johnson

hey joe. i got gas in both carb bowls and i got my start up problem solved i believe but i now either have a coil gone bad or one of the carbs are not getting fuel to one of the cylinders. i was able to run the boat but not much power now. feels like it was just running on one cylinder. Thanks again for all the help.