1989 Merc surging

[Rickshaw]

I have a 1989 Mercury 90 HP outboard that acts like its starving for fuel when running over 4000 rpm. If I sqeeze the fuel line primer bulb at these rpms it clears up for about a minute, then acts like its not getting enough fuel again. I have replace the fuel filter and all the fuel lines from the 18 gallon tank to the fuel pump on the motor. Any ideas?

 

[rndn]

Re: 1989 Merc surging

Welcome to the forum!!
When is the last time the fuel pump was serviced? It sounds like it is running lean and then by squeezing the bulb you're giving it more gas. You really don't want to run the engine lean as you'll be looking for a new powerhead/rebuild.

 

[adam89k]

Re: 1989 Merc surging

I have a 1989 Mercury 90 HP outboard that acts like its starving for fuel when running over 4000 rpm. If I sqeeze the fuel line primer bulb at these rpms it clears up for about a minute, then acts like its not getting enough fuel again. I have replace the fuel filter and all the fuel lines from the 18 gallon tank to the fuel pump on the motor. Any ideas?

Keep it simple I had the same problem. Remove your gas cap then try it, if it runs fine your vent is pluged.

Good luck