Re: 07 mercury 150 efi bogging
You will need to test a few things to determine if you have a fuel or electrical prpoblem.
Fuel pressure should remain constant throughout the RPM range, if the pressure drops when the condition occurs the closer inspection of the fuel system is needed. Check this first as a limited fuel at WOT will cause a lean condition and will raise piston temps and cause damage. Once fuel pressure is ruled out then proceed to checking the ignition system.
An inductive tach is an easy method of determining of you are loosing spark one a cyl when the problem occurs. Test each cyl to see if the RPM reading fails when the condition occurs. If so then DVA testing of the stator will be required.
It may be possible for a bad rectifier to cause high RPM irregularity, disconnect the yellow stator wires from the rectifiers and test run, if this makes a positive difference then further testing of the rectifiers is needed.
