2500 rpms at WOT??

[88seville100]

This is the second time the motor is doing this. The first time I was cruising just fine and then the rpms dropped to 2500 and wouldnt go past it. I checked the oil tank for the oil injection and it was kinda low so i added some. It ran great after that so i figured it was like a low oil saftey governor or somehting.

But then yesterday it did the same thing when i was cruising, but i topped off the oil and no change. if i put the motor in neutral it will rev up just fine, but in gear it sounds like the rpms want to go up, but it seems like there is some kinda governor holding it back? What do you guys think?

btw its an 88 100hp merc on a sea ray seville. i also checked the spark a few weeks ago with a timing light and all cylinders were firing.

 

[CharlieB]

Re: 2500 rpms at WOT??

You haven't determined yet if it is a weak fuel supply or weak ignition at RPM.

Both problems will display your symptoms, yet allow no load RPM.

If the boat is still in the water, try squeezing the primer bulb when it won't speed up, if that improves then you may have a restricted fuel supply, weak fuel pump, or air leaking into the fuel lilne before the pump.

Also try momentarily 'bumping' the choke/fuel enrichener to provide a heat beats of additional fuel to see if the motor is running slightly lean from dirty carbs.

If NO improvement, then you need to test the high speed windings of the stator to ensure adequate voltage at RPM under load. No load voltage output from the low speed windings is enough to rev the motor, but the additional air drawn into the cylinders under load acts as a larger insulator on the spark plug, requiring more voltage to arc across the same gap.

Download the free CDI Ignition Troubleshooting Guide found thru this link

www.rapair.com

Look up your model and follow the detailed testing to determine of indeed you have a weak ignition.

You may need a DVA Meter to test stator voltages once disconnected from the ignition module.