1994 Mercury 115hp problems

I have a 1995 Astro fish-n-ski with a '94 Mercury 115hp.

First issue... The past 3 times its been out, it's had trouble turning over. The starter is barely turning the motor over at first but after a few attempts, it picks up and turns over fine. The battery is fully charged... Is the starter worn out or is it something else?

Second issue... This past weekend, the high heat/low oil light and alarm came on while pulling a tuber so i immediately turned off the motor. I checked the oil level (again) which was at half a tank so i thought it may have overheated. Started again, motor ran for a couple of seconds then cut itself off. Am i looking at the oil injection system fouling up?

Thanks,
TB

Re: 1994 Mercury 115hp problems

Maddoxsdaddy said:

I have a 1995 Astro fish-n-ski with a '94 Mercury 115hp.

First issue... The past 3 times its been out, it's had trouble turning over. The starter is barely turning the motor over at first but after a few attempts, it picks up and turns over fine. The battery is fully charged... Is the starter worn out or is it something else?

Second issue... This past weekend, the high heat/low oil light and alarm came on while pulling a tuber so i immediately turned off the motor. I checked the oil level (again) which was at half a tank so i thought it may have overheated. Started again, motor ran for a couple of seconds then cut itself off. Am i looking at the oil injection system fouling up?

Thanks,
TB

Click to expand...

First issue is the starter motor needs rebuilding. The brushes are at the bottom of the starter, on the end of the armature, and the carbon brush debris piles up till the starter shorts. It's weird, because the starter doesn't sound bad like a bad car starter, but draws very high current, which slows the starter down. Just did mine. It fooled me into buying a $40 battery for $80 at a marina.
It's not hard to clean it up, have the armature faced, and throw in a set of brushes. The maintenance manual even has a drawing of the tool you need to make to hold the brushes.

Second issue, When the oil alarm goes off, you assume the oil system failed. Do not proceed until you mix oil with your gas at 50:1. Worst case, you run smokey till you burn off the extra oil. You can, however, operate the motor without damaging it. I've been through that recently also, turned out to be the alarm module. That also in in the maintenance manual you should own.

I suspect you seized the power head.

hope it helps
John

Re: 1994 Mercury 115hp problems

You can always have the battery load tested to be sure that isn't the problem. It's normally a free test at any auto parts store or service station.

With the alarm, the oil level and over heat sound different. Was the alarm a constant beep or an intermitent beep?

Re: 1994 Mercury 115hp problems

The alarm was a constant blaring whine.... REALLY hoping no damage was done. The low oil sensor and the alarm were both replaced a couple of months before i bought the boat.

Re: 1994 Mercury 115hp problems

That's the overheat alarm.

Re: 1994 Mercury 115hp problems

Ok... here 's whats wrong. The starter is just plain worn out. Is an aftermarket starter as good as oem?

Next... The magnet that is glued to the inside of the oil tank that the sensor works off of came unglued...its sitting in the bottom of the oil tank causing a faulty alarm. Needs a new tank or taking off oil injection and pre-mixing fuel/oil.