1983 80hp Merc hesitates & dies after warmed up

[aspurbeck]

Seems to run great until after about 10minutes being warmed up. It starts to hesitate when you put the throttle down and progressively gets worse.

I replaced all fuel lines. Replace fuel pump gaskets, replaced one float that had one side full of fuel so thought that was it.

Seemed to run much better until 10-15minutes of running full throttle. Started to hesitate when putting throttle down. Still starts but water coming out cheat hole seems marginal but does come out.

I did not do a complete carb rebuild. Only replaced main gaskets and one float and needle.

Any thoughts on next steps to check for? Thanks in advance! -Andy

 

[aspurbeck]

Re: 1983 80hp Merc hesitates & dies after warmed up

Just wanted to add that my issue sounds a lot like the guy with the 73 merc that bogs down under load and mine had sat for a season according to the guy I purchased it from a couple weeks ago.

 

[aspurbeck]

Re: 1983 80hp Merc hesitates & dies after warmed up

I read in another thread that adjusting the fuel mix may be required and the float position is critical. I measured mine when I cleaned the carbs (not complete rebuild) and adjusted but they were approx. 1/16th to 1/8th in higher then the 11/16th called for in the manual from the top of the carb.

Anyone think that a 16th or 1/8th off could be the issue?

The fuel mix screws are both set to 1 full turn out from fully seated.. Sounds like this will be a good easy next step...

Thanks! -Andy

 

[Coloradolakeboy]

Re: 1983 80hp Merc hesitates & dies after warmed up

You can check the floats and needle seats by pulling the cowl and air cover.
The Merc manual says to turn the bottom carb bowl upside down and measure the distance the floats extend beyond the bottom half of the carb. Thus, I unfamialiar with your meaurements. WH carbs need the floats 1/16" extended beyond the edge of the carb (upside down)
Squeeze the primer bulb hard with the motor level as in the water. Start it on muffs or in the water if you can. Check for fuel coming out the front of the carbs. I am guessing that you replaced the fuel pump diaphram. If fuel is coming out, you may have a stuck
needle seat. Adjust the idle mix crews per the instructions on this site. If none of that works, check the stator with a DVA.

 

[aspurbeck]

Re: 1983 80hp Merc hesitates & dies after warmed up

Followed the manual for carb fuel mix adjustment. Made some minor adjustments, put it on the lake tonight and seems to have made a difference.

I'll really put it through the paces this weekend after replacing the water pump and see if it's consistently running better.

If it's marginal or still hesitate when I put the throttle down I may just do a full carb rebuild.

Thanks for the help! -Andrew