1988 mercury 90 loss of power

Hey guys, I got a 1988 mercury 90 2stroke 3cyl, I just put it on my boat 2 days ago and the problem I am having is the engine will sometimes cut out mysteriously under load its not always consistant and it will run like its runningon 2 cylinders and seems to smoke a lot. A couple of people I have talked to said it might be a bad coil pack???? It will run perfect for quite a while and then just crap out out of the blue??????? My controls are also making a beep beep beep when the motor is stone cold and all the time

Re: 1988 mercury 90 loss of power

Any ideas?

Re: 1988 mercury 90 loss of power

Anything?

Re: 1988 mercury 90 loss of power

Anybody got anything?

Re: 1988 mercury 90 loss of power

You may have two separate problems.

First, the rapid beeping is the oil alarm, often caused by an adhesive failure between the magnet and the oil level float. Test this by un-plugging the blue wires that are on the magnetic sensor on the bottom of the oil tank. If unplugging the blue wires stop the alarm you will need to replace the tank, it is next to impossible to repair the float.

Second, an intermittent performance problem needs testing to determine if it is an ignition or fuel problem.

Troubleshooting should always begin with a compression test and a spark test using an adjustable gap spark tester set to a 7/16 inch gap. Without a bright blue arc the ignition will not reliably fire under load.

While the spark plugs are removed , inspect for carbon deposits that may be shorting, causing misfires at larger throttle openings.

Conducting these tests and re-posting your findings will help us to guide you further.

Re: 1988 mercury 90 loss of power

Well here is the deal, the engine will run perfect for several hours and then for no reason at all it will run about 30% of max power at WOT, and then for no reason it will start running at 100% for 5 minutes and then for no reason it will start running at like 30% power again. I know the oil injection works because it is using oil. I started moving the spark plug wires around when it was running and it caused it to completely die on me a couple of times. also when the engine is running at like 30% it smokes really bad. also if i disconnect the purple wire coming out of the ignition module it will cause the intermittent beeping to stop. i also dropped the engine when i was installing it

Re: 1988 mercury 90 loss of power

ok i pulled the blue wires going to the oil tank and the result was a soild beep. i put the blue wires back together and the intermittent beeping started again

Re: 1988 mercury 90 loss of power

If I turn the key to the "on position" the intermittent beeping will start, it dosent even have to be running

Re: 1988 mercury 90 loss of power

i ordered new coil packs and new sparkplug wires. ill repost if anything happens

Re: 1988 mercury 90 loss of power

Maybe 5 months late but had the same problem....exactly.Turned out it was the switch box,both sides.Not enough power to run all six cylinders and one of them had censor attached for oil beep beep beep till it wormed up/reved up then stopped.replaced both($$$).Problem gone.

Re: 1988 mercury 90 loss of power

Oh yeah I should tell you that when you turn the key you get the beep beep just to let you know it is working.