power loss

[scott68]

i have a 1984 johnson 70 hp that lost power last weekend. it just lost rpms, at first i thought that i may have forgot to put oil in the gas but not 100% on that. i got it back to the marina and pulled the plugs and all were dry. i did notice water collecting on top of the exhaust manifold so i replaced that. i have 95 psi compression in all 3 cylinders, getting spark getting fuel but after i changed the gaskets today i took it out and still have a loss, but it wasn't as bad as over the weekend. i also put a bottle of drygas in 1 tank as i got some water in when i was cleaning, could this have done damage? not sure what to do now, any help is great. thanks, scott

 

[OBJ]

Re: power loss

Couple things to do Scott.....

Make sure the fuel tank is vented and fuel supply is unristricted to the engine. Check the primer bulb will pump up firm before starting engine.

When you experience the power loss, start pulling spark plug wires. Look for the one that doesn't do anything to the engines performance.

Take a spray bottle of premix with you. When the power loss occurs, shoot some premix into the throats of the carbs. If the power picks up, you likely got a fuel supply problem or the carbs need a cleaning and overhaul.

 

[scott68]

Re: power loss

many thanks OBJ, i finally was able to get to the boat today and check and only had to go as far as the carbs. upon spraying into the carbs, the bottom 2 started to stall out when sprayed in and the top the RPM's picked up and the boat tried to get going. i am ordering rebuild kits from here and will attempt to do this myself. with my manual in hand, is there anything in particular that i should look for and what is the best way to clean the parts? i want do do it once and do it right!! thanks, scott