Logo
FULL SITE MENU

Johnson 40hp linkage adjustment

C

Costnerkid

New member
Okay new here and just as new to outboard world

1993 Johnson 40hp original with boat which is tracker 17ft when you go to take off it’ll rev up great and then stops at 3k rpms and you’ll cruise about 9mph if you intermittently push the “choke” it’ll take off about 4500 rpms and run about 25mph this boat was ordered and owned by my father since new he took it to a shop to have winterized every year for 3 years then parked and I finally started working on it cleaned carbs new plugs new fuel all new fuel lines new fuel solenoid no vro pump running mixed gas now don’t know where to go found something for the timing linkages it says upper linkage should be 2 1/16 mine measures 2 13/16 but never been worked on and can’t find any verification of this measurement please help
 
Sounds like its not getting the fuel it needs. Aside from the linkage measurements, you could have a fuel supply issue at the pump/VRO. It must have had ethanol in it at one time in order to mess up the VRO, so the fuel pump part of it could be injured. I started working on my own stuff at an early age because I learned that for every good "shop", there were 4 lousy "shops". This little 1965 Fisherman "my baby", has nearly 3500 hours on it and the original carb, fuel pump, and gas lines.....including primer bulb and water pump. Back in those days they had quality rubber.....the real stuff, not this synthetic imitation rubber made from oil. NEVER any ethanol and since 1975 only 100:1 Amsoil synthetic 2 stroke oil. Thats why the new impellers need replacement every 5 to 7 years, they are not quality rubber anymore. The rubber now is synthetic/mix and has a short shelf life. Before you buy tires for your car or truck, be sure to check the date code.
 

Attachments

  • My little '65 Evy.jpg
    My little '65 Evy.jpg
    64.1 KB · Views: 67
Last edited:
This motor hasn’t ran since 96 before ethanol was anything popular I’ve only ran non ethanol the vro pump wasn’t working right so it now has a straight fuel pump with brand new lines completely. I assume lack of fuel as well carb rebuild kit should be delivered tomorrow but what gets me is that it takes off great then loses control if the timing linkage is to long then the timing isn’t advancing to its proper place which means I’m slightly retarded for wot??
 
Okay then you should be safe on that ethanol. Mandates for ethanol are being scrutinized now and Florida as well as Hawaii have reversed their mandates. Maine has "banned" ethanol. Iowa seems to be the only state still pushing for mandate. Louisiana and Washington are only at 2 percent ethanol in total volume of sales. I am stuck in MN where ethanol in mandated (at 10 percent ouch!), so sad.....but lots of business for small engine and marine mechanics.
How did the "out of adjustment linkage" work under acceleration, then "fall off"? It would be constant......it wouldn't accelerate to begin with, it would just BOG! For sure the VRO failed from drying up and non use with probably just enough old fuel residue to injure it. Make sure you clean out the main jets with something like "throttle body" cleaner and then physically open them up to proper size with a welding tip cleaner. These are good to use because they are not too abrasive to damage the orifice, yet strong enough to clean out the deposited coating, when used with a strong solvent like "throttle body" cleaner.
 
Last edited:
Sorry poor wording the linkage doesn’t fall off the power falls off and it’ll just fall on its face after 3k rpms carbs have been everything but rebuilt which will happen today replaced the old plastic fuel manifold with a brass one and like said all new fuel lines. There’s not much left to replace fuel wise
 
Well after work I’m going to adjust timing linkage to measurement I found online and also rebuild kit on the carbs and see what it does and will check back thank you
 
Be sure to pick up a welding tip cleaner and throttle body cleaner spray for these jets, this will be the last time to take it apart, brother. Time is valuable.
 
Back
Top