Nothing above 2000

[Brent Broome]

I have a 1971 Mercury straight 6, 135 HP outboard. It has sat for several years and I had the carburators overhauled. I took the boat to Lake Powell and it ran great. The next trip I couldn't get the motor to go above 2000 RPM'S. I changed props from a 19 pitch to a 15 pitch with no difference in performance. Anybody have any ideas of what could be wrong?

 

[Backlash]

Re: Nothing above 2000

Well Brent, You'll have to go through some troubleshooting procedures & get back to us with more information. Sounds like you may have dropped a cylinder (or two). To find out, get the motor running (be sure you've got water going to the water pump) and pull spark plug wires one at a time. If you detect a drop in RPMs or m discernable miss that means the cylinder is good. If you don't see any change, the cylinder is bad. Once you've isolated the bad cylinder(s), you can proceed with finding out what is causing the problem (i.e., no spark, no/low compression, no gas, etc.). Let us know what you find.<br /><br />P.S. Gene Fullmer was a GREAT middleweight champ!

 

[Walter]

Re: Nothing above 2000

Brent...<br /><br />Baclash is giving excellent advice... I'd only add that you may want to try the most simple things first. <br /><br />1) Fuel restriction... Be sure all fuel supply lines are clear with no kinks etc... Is there a fuel filter in the system?? If so, check it too. Have you tried pumping the primer bulb when the engine is failing to gain proper RPM? If not...try that and see if the RPM increases.<br /><br />2) Full throttle... Are the throttle control cable & linkages properly adjusted to insure you're getting full throttle??<br /><br />As Backlash said...you've got a bit of troubleshooting to do then let us know your findings. Let's just hope the problem is something simple to fix. <br /><br />Good luck...<br /><br />Walt