86 Mecury Black Max 150

[met128]

I have a problem with the motor not making power when in gear. In N the motor runs great but when you put a load on it (in the water) it has no power. I just replaced the water pump and did a oil change. I am in the process of changing the fuel pump gaskets. I have checked the compression on the motor seems fine. I also have the Beeper sounding all of the time. I am in the process of replacing the oil control box. Is there a tell tail sign that a lower unit has to be replaced???I know alot about Auto motors and a bit about 2cycles but this one has me questioning my abilities... Please help me <br /><br /><br /> Met128

 

[JB]

Re: 86 Mecury Black Max 150

Ahoy, Met. Check that all cylinders are firing. Do it with the engine running at no-load. <br /><br />Your symptoms are classic for one or more dropped cylinders.<br /><br />Red sky at night. . .<br />JB

 

[met128]

Re: 86 Mecury Black Max 150

Thanks fo the reply.....I tried another compression Test and found one bank all have 120 psi and the other bank of cylinders to low compression (85,75,90). So I replaced a head gasket (2 broken bolts) . After doing this I had no change. The cylinder walls looked as good as new. I am thinking I have some ring glazing but not sure. I was told by a shop to try squirting some oil down into the cylinder to see if the comression goes up. If I have ring glazing what product should I use to try to restore the compression. <br /><br />met128

 

[Fouled Plug]

Re: 86 Mecury Black Max 150

Could be ring sticking, too. I've had luck with Merc's Power Tune and Yamaha's Ring Free. Some others like Seafoam, but I haven't tried it. The power tune just sprays from a can, the ring free is added to the fuel.

 

[met128]

Re: 86 Mecury Black Max 150

Well I have restored compression but I now have a new problem. After installing a new head gasket and upper chamber gasket on one bank, it now gets hot. I have 2 new stats and a new water pump.I have do have water up to the head. The other bank is just warm to the touch but the one that gets hot is very hot after running for only a minute. I am thinking that its a lean mixture problem or a timing problem. I also have checked spark and found that I had one cylinder not firing but I fixed the problem with a new switch box. Help ME

 

[clanton]

Re: 86 Mecury Black Max 150

Check pressure relief valve. Check engine temp with melt stick or temp gun.

 

[met128]

Re: 86 Mecury Black Max 150

I have also replaced the idle cut off valve. I can't seem to beat the overheating problem. I have gone over every inch of the cooling system and just can't seem to find what is going on. I will be taking off my lower unit today to inspect it for the third time..... On the ears should I see a steady stream at idle? I also think that I let the silcone on the lower unit between the exaust chamber dry. If it leaks there could it cause the problem I am seeing on the ears? I thank all of you for your time and info..

 

[slalom]

Re: 86 Mecury Black Max 150

check cdi box.<br /><br />had same problem with merc 4 stroke. clean carb, changed gear oil, but was only one cylinder getting power!! <br /><br />good luck<br /><br />dylan