Missing Merc 150 XR2

[333kelly]

I have a 1987 Merc 150 XR2 V6 that misses as if a cylinder is cutting out at cruising speeds. Most times it is barely noticible, but sometimes it is very obvious that a cylinder or 2 is cutting out.It seems to idle rough, but this being my first Merc, I dont know if this is the nature of the beast.It seems to be more noticible in cooler weather and gets better as it warms up.It goes like a scared rabbit when it runs well. It red lines at 5400 RPM but when it is missing, it only reaches 4800 or so, then jump up to 5400 when the cylinder cuts in. The voltage sometimes is at 13 volts or so, then it will jump up to 16 and return to 13 at random. It is driving me crazy. I have checked all of the connections.All spark plugs have been replaced and it has good spark at idle. It is slowly driving me crazy.

 

[dakk1]

Re: Missing Merc 150 XR2

I would disconnect the rectifier and see if the miss goes away.<br /><br />Dave..

 

[Chris1956]

Re: Missing Merc 150 XR2

If dakk1's fix doesn't work, you might try cleaning the main jets in the carbs. When these motors run too lean they will sneeze.

 

[333kelly]

Re: Missing Merc 150 XR2

dakk1<br />What wires do I disconnect. The ones from the Stator or all of them. Can you just remove the stator wires from the circuit without burning up the stator.<br />Thanks for your time<br />Greg

 

[dakk1]

Re: Missing Merc 150 XR2

Disconnect either yellow wire from the stator to the rectifier and tape it off. I have never had any problem with this as a troubleshooting procedure and have done it many times. I do not know what the long term effects, if any, would be. If you are uncomfortable with it, you could completely remove the rectifier from the circuit and Ohms test it. There is a thread on the board http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=29;t=019316 , with a link and an explanation on how to test it. <br /><br />Dave..

 

[eagleclaw19]

Re: Missing Merc 150 XR2

Hello yall. I have an 86 Merc XR2 Black Max. I believe that I have the same problem. I am very interested to know if this does the trick. I have been told that I have a needle that is sticking. My boat runs like a spotted ape at full throtle but it is constantly runing up and down at idle. In fact it is hard to keep running at idle most of the time, but sometimes it will be running rough and then it will just kick up and run fine. Please help.<br />Jonathan Davis<br />jldavi19@yahoo.com

 

[333kelly]

Re: Missing Merc 150 XR2

Sorry for the late reply. I havent been out in the boat in a while. (Work really interferes with my life)The stator disconnect didnt make any difference. I havent tried the carb thing as it is still in the water. It is funny that it seems to get worse in the cooler weather. Today, I was cruising and it was running at 4600rpm, then it cut in or something and took off, right up to 5500 and just about knocked me over.Anything else will be appreciated.Thanks again.