1984 75hp Johnson Bogs down at initial acceleration.

[Rockchalk]

Motor had carbs overhauled and new fuel lines two seasons ago. Runs nice except at initial acceleration where if I hit the throttle hard at all it bogs down and dies? really have to ease it up to speed and then it runs like a champ. Suggestions on any simple adjustment I might try. My tech can?t touch it for a week or so and I would like to see if I can get it running better before the weekend. Thanks!!!

 

[Joe Reeves]

Re: 1984 75hp Johnson Bogs down at initial acceleration.

You didn''t say BUT if it ran okay 2 seasons ago and last season, and you haven't changed any linkage adjustments, that sounds like either the timer base is sticking slightly (under the flywheel) which would cause retarded spark, OR the high speed jets that are located in the bottom center portion of the float chambers are somewhat restricted.

If a sticking timer base, it's usually a slightly tight "L" clamp, in which case carefully pry it up ever so slightly.

Restricted jet.... remove the bolt/screw from the front bottom portion of the float chamber, then clean the jets with a piece of single strand steel wire.

 

[Rockchalk]

Re: 1984 75hp Johnson Bogs down at initial acceleration.

Thanks for the quick reply Joe.

When I got this boat (16? Lund) it hadn?t been run in years. My tech rebuilt the carbs, changed the impellor, changed rotten fuel lines, put in fresh plugs and away I went. The engine has always had the problem of bogging down at initial acceleration since I?ve had it but it runs so nicely otherwise I just lived with it. Going to do a lot of boating this weekend and I thought I would see if I can get it resolved. Thnaks again

 

[jtexas]

Re: 1984 75hp Johnson Bogs down at initial acceleration.

...The engine has always had the problem of bogging down at initial acceleration since I’ve had it but it runs so nicely otherwise I just lived with it....

check to see whether the throttle cam hits the roller (starboard side of the middle carb) right on the mark when you advance the throttle - the tiniest bit early will cause that symptom. The roller is attached to a slotted bracket so it can be adjusted.

 

[Rockchalk]

Re: 1984 75hp Johnson Bogs down at initial acceleration.

Thanks JTex... I'll give that a look.