65HP Merc Nightmare

[sprattman]

I've been having nothing but trouble with this engine. I believe year is between 72-76 (blue stripe on cover) It's a three cylinder, 65 hp. I have had the engine rebuild, new Distributer, rebuilt starter. When engine does start it's rough running, very hard start, when it does start you need to keep handle up (for choke? high idle) to keep it running (even then it doesn't reeve to high rpm's). I am currently having then engine looked at by a Merc Tech, he has checked compression and said it's good. Boat will run ok once you get going at a good speed...then suddenly it begins to die out....if you squeeze the fuel bulb? (or primmer) it picks up again ??? any idea's????HELP !!!Hopefully this makes sense I'm a bit of a rookie with boats

 

[Elmer Fudge]

Re: 65HP Merc Nightmare

It appears that you might be suffering from fuel starvation, check the lines for air leaks and make sure that the tank is venting.<br />Try changing out the fuel pump diaphragm and see.<br /> Are the plugs new?

 

[Stumpys]

Re: 65HP Merc Nightmare

Sprattman...<br /><br />My 65 did the same thing and I rebuilt the fuel pumps and replaced the primer bulb. Now it runs and idles fine.<br /><br />Just my 2 pennies worth!

 

[sprattman]

Re: 65HP Merc Nightmare

Thanks for the replies...I'll keep y'all posted

 

[sprattman]

Re: 65HP Merc Nightmare

I spoke to the tech today regarding my engine, he indicated that there was a float or ball ?????? inside the fuel pump that was sticking open / causing the engine to flood..does this sound like it would cause the above problems.. he said the fuel line are ok..

 

[Elmer Fudge]

Re: 65HP Merc Nightmare

The float should be in the carbs,the inside of the fuel pump is made up of diaphragms springs and check valves,a fuel pump rebuild kit costs around $10.00 to $15.00. If the float is sticking, you will need to clean the carbs, the tech that rebuilt your engine should've done that in the process to begin with.

 

[sprattman]

Re: 65HP Merc Nightmare

thanks Elmer !! the problem was a check value.....gonna test it this weekend...Thxs 4r your input.

 

[natedennis]

Re: 65HP Merc Nightmare

better watch those tech. not to techy sometimes.

 

[sprattman]

Re: 65HP Merc Nightmare

I had the boat out this weekend, Great to finally see the lake. The boat still has one problem, when you first take off....it hesitates won't take off, if you cruise at a slow speed, you'll feel the boat suddenly pick up, after that... the boat picks up fine and runs great...if you attempt to force it down at the beginning it will die out. I haven't changed the fuel line, the one with the primmer bulb ..should I ?? Any help would be graetly appreciated.

 

[sprattman]

Re: 65HP Merc Nightmare

the above problem occurs every time you stop then restart

 

[sprattman]

Re: 65HP Merc Nightmare

one more question...should I have the vent on the fuel taqnks open fully ??????Anyone out there Please Help

 

[sprattman]

Re: 65HP Merc Nightmare

Originally posted by Stumpys:<br /> Sprattman...<br /><br />My 65 did the same thing and I rebuilt the fuel pumps and replaced the primer bulb. Now it runs and idles fine.<br /><br />Just my 2 pennies worth!

 

[Elmer Fudge]

Re: 65HP Merc Nightmare

Hey spratman, what were the results of the compression test? and what is your RPM at wot and at idle?

 

[sprattman]

Re: 65HP Merc Nightmare

I don't have the result of the compression test I was just told the cylinders were equal? The boat is running great...except for take off, at idle it;s around 1 on rpm gauge, with high idle arm up it's at 3 on rpm gauge. It's weird when taking off regular or pulling tubber...if you push down all the way boat dies out...if you only push down slightly and cruise slowly (for approx 1min) the boat suddenly picks up pwr, once this happens you can push it down hard..boat runs great ?????

 

[sprattman]

Re: 65HP Merc Nightmare

Hey Elmer, I spoke to tech who has fixed up the majority of problem on boat, he thinks a carb may be running lean ? how would I adjust this ? Thxs in Advance.. Sprattman

 

[Elmer Fudge]

Re: 65HP Merc Nightmare

My inclination leads me to think that's the probable cause,from here on it should be smooth sailing

 

[emckelvy]

Re: 65HP Merc Nightmare

Just move the idle mixture screw on each carb 1/8 turn in the counter-clockwise direction. <br /><br />Try to accelerate and see if it bogs down. If so, move each screw another 1/8 turn and see if that helps. You sound like you are very close to optimum setting and shouldn't need to move either screw more than 1/2 turn CCW. <br /><br />You may also want to seat the screws fully CW and then turn them both back out approx. 1-3/4 turns as a starting point. That way you know both are approximately equally adjusted.<br /><br />CCW is rich, CW is lean on the idle screws and they are located at about 1-o'clock on the each face of the carbs.<br /> <br />HTH.......ed

 

[sprattman]

Re: 65HP Merc Nightmare

Beautiful, going North this weekend will give it a shot !!!!!Thanks Again for all the help.<br />Spratter