1977 Mercury 85 hp starts dieing out at wot. Gotta prime bulb to keep from dieing

[andrewbabich]

1977 Mercury 85 hp starts dieing out at wot. Gotta prime bulb to keep from dieing. Something is up with the fuel delivery. I have a brand new fuel line. Its possible air is getting in at the connection to my 6 gallon plastic tank but I don't think so.

Do these motors have a fuel pump that could be the problem or does the carb just suck all the fuel from the tank?

I threw a spark plug wire wrap tachometer on it and was only seeing 3000 rpms, but I don't think that was accurate because we were doing about 30 mph which felt pretty good.

 

[Chris1956]

Re: 1977 Mercury 85 hp starts dieing out at wot. Gotta prime bulb to keep from diein

The parts list for that motor shows a single triangular fuel pump on it. I recommend your rebuild it and make sure all fuel filters and screens are clean.

 

[Chris1956]

Re: 1977 Mercury 85 hp starts dieing out at wot. Gotta prime bulb to keep from diein

I would be surprized if you are seeing 30 MPH at 3000RPM. You would need a very light boat and a 23" pitch prop or so. I suspect either the Tach or Speedo are incorrect.

 

[andrewbabich]

Re: 1977 Mercury 85 hp starts dieing out at wot. Gotta prime bulb to keep from diein

Yea I think the tach is not reading the right number.

I checked the fuel filter screen and that looked good.

I can rebuild the fuel pump. I've never done that. Thats probably a good start. Is it a simple job.

 

[Chris1956]

Re: 1977 Mercury 85 hp starts dieing out at wot. Gotta prime bulb to keep from diein

yes, very simple. Make sure you put the one way valves in the proper way. The primer bulb should be able to push fuel thru the fuel pump, if they are installed correctly.