1985 70hp Johnson - HELP !!

[iwombat]

Re: 1985 70hp Johnson - HELP !!

Not to be too blunt about it, but I could sit here and type out pages of irrelevant test procedures all day.

Lets see if the spark checks out, then on to what needs to get done.

 

[jblaiz]

Re: 1985 70hp Johnson - HELP !!

i have a similar outboard (1990 60 HP) that had the same symptoms yours is having. Also: i did the same damned thing with replacing power pack, fuel delivery etc etc.

MY problem was a crack in the lever of the primer solenoid. the problems was hard to catch because fuel would only leak under load and while powering up.. Just a thought of something else to peek at - I spend ALL THIS PAST SUMMER replacing electrical components, fuel delieveries, rebuilding carbs, etc etc.

 

[emdsapmgr]

Re: 1985 70hp Johnson - HELP !!

I'd take an inductive timing light and a helper with you next time out on the water. When the engine starts to act up, check each of the 3 plug leads for spark. Check when the engine is under load. Hopefully, all 3 with show constant, rhythmic strong flashes. Look for intermittent or no fires. If you see problems, there are two other ignition components you have not mentioned checking, the stator and the timer base. Each can be checked electrically (with special tools and the service manual) and can contribute to the problems you mention. Electrical problems seem to show up once the engine reaches normal operating temps. All the ignition components are expensive, so a good upfront analysis is cheaper than just replacing components at random. I don't think the 85's had the SLOW system yet, so the pack should not be limiting revs to 2500.

 

[boatman48]

Re: 1985 70hp Johnson - HELP !!

jblaiz - how did you find the crack in the primer solenoid ? i've had mine apart
and nothing jumped out that was obvious. of course i was not looking
for a crack... also, if i squirt pre-mix in the carbs and it makes no difference
do you think it's safe to rule out fuel delivery ?


emdsapmgr - beyond, power pack, coils, plugs, wires , " timer base & stator "
are there any other components ? would a bad thermostat contribute to
my symptoms ?

 

[emdsapmgr]

Re: 1985 70hp Johnson - HELP !!

I doubt the thermostat is the cause of any of your problems, but a laser temperature gun would help determine if it is functioning propely. If the thermostat is stuck open, the engine will run cold. Cold running engines will smoke more and can accumulate carbon around the rings over a long period of time. If the thermostat is stuck closed, you will get an overheat horn at idle after just a few minutes. You did not mention any of these symptoms as being a problem.