Mercury 150 Black Max XR2

mulliganmagic

Petty Officer 3rd Class
Joined
Jan 9, 2004
Messages
82
The last two trips out this motor has given a lot of trouble. It does have oil injection, but since we've heard that you can't trust the system we put 16 oz of oil into the 12 gallon tank to act as a back up incase the oil injection stopped working. So, the engine was recieving oil from the oil injection as well as from the gas tank. At the same time we also added brand new spark plugs from an auto store (NGK BU8H). I've heard bad things about auto store plugs anyone else heard this? Some people say to buy them from the boat dealer.<br /><br />Now what happened is the motor ran well for a few minutes, but then it started loosing power on and off. It would have more power some times more than others. But then it cleared up and we just descided to go along on a ride. The engine ran fine up to WOT at about 5500 and then backed down to about 4000 and after about 4 miles it started making a noise so I let off of the gas. Then when we tried to go it wouldn't idle well at all but it would rev with a different sound than normal. It took several minutes, but I finally got it to go. The engine would not bring the boat on plane. When I would try to give it gas it would shake and bogg. So I headed back to the boat ramp at about 1000 RPMs and it sounded like it was missing and the Tachometer hand would move while I held it at a steady throttle position. The fluctuation would be maybe about 100 RPMs. Then, after idling along at 1000 RPMs for about 1.5 miles it smoothed out and I gave it gas and it planed out and made it back, however the sound was slightly different than normal. <br /><br />We thought that the plugs had been fouled, so my grandfather put the old plugs back in it. It had always performed very well with these plugs. We also added 4 more gallons of gas to the tank to dilute the oil that we had added. Took it to the lake and it did the same thing again and maybe a little worse to boot. The motor was smoking very badly as well. Finally, the last thing that I notised is that 3 of the rubber covers over the power pack connections were melted located on the bottom of the power pack.<br /><br />Any suggestions or thoughts of what it might be would be appriciated.
 

jaxsun

Petty Officer 3rd Class
Joined
Aug 9, 2004
Messages
84
Re: Mercury 150 Black Max XR2

Originally posted by mulliganmagic:<br /> 3 of the rubber covers over the power pack connections were melted located on the bottom of the power pack.<br /><br />
i'd start with a new pack
 

dakk1

Chief Petty Officer
Joined
Apr 22, 2003
Messages
418
Re: Mercury 150 Black Max XR2

Get a spark tester and see if your getting fire on all your cylinders. Overheated power pack doesn't sound good. Pull back the rubber covers and see what it looks like underneath. What does your rectifier look like? Those packs are about $135 each.<br /><br />Dave..
 

mulliganmagic

Petty Officer 3rd Class
Joined
Jan 9, 2004
Messages
82
Re: Mercury 150 Black Max XR2

Both rectifiers look good. The power pack that has the melted contacts is on the starbord side of the motor. The other power pack on the port side (the switchbox power pack I think) looks fine, but I didn't take the cover off of it to examine very closly. Do you think that the extra oil that we put in the gas could be the cause of this making plugs foul out?
 

Coolmaker

Petty Officer 2nd Class
Joined
Mar 15, 2005
Messages
134
Re: Mercury 150 Black Max XR2

Replace the power pack, the extra oil should only make it smoke more at idle and startup.
 
Top