88' Merc 80hp 3cyl intermit rough idle

[Dallenx]

Each time I tilt the engine down from being either cold or warm, the engine runs rough. Do not even have to tilt engine, just leave it off for a while. It sounds like it is missing. It did this 2 years ago so I rebuilt the fuel pump which had bad check valves which fixed it. The rebuild now did not fix. Replaced external fuel/water filter and see thru filter. Timing is good. Unkown if cyl 2&3 have spark. Engage choke during rough idle and engine will die. <br />While running at WOT the engine is bogged and I can only get half speed. At either idle or WOT, the engine will usually PICK UP and work great.<br />S/N OB195172

 

[The Marine Doctor]

Re: 88' Merc 80hp 3cyl intermit rough idle

While the engine is running squeeze the primer bulb and see if the engine dies.<br /><br />TMD

 

[Dallenx]

Re: 88' Merc 80hp 3cyl intermit rough idle

Nope it doesn't. Put an inductive timing light on cyl 1, 2 & 3. No spark on #3. Ohmed coil and it's ok. Swapped with #2 but no spark on #3. Changed plug and swapped plug wire. No good. Tested Trigger and all wires have about 1250 ohms. Wire from switchbox to coil has zero ohms. Ground to coil is good. <br /><br />How do you test a switch box?<br />Merc p/n 332-7778-A1

 

[The Marine Doctor]

Re: 88' Merc 80hp 3cyl intermit rough idle

Unfortunately with a DVA meter.<br /><br />But feel free to move the trigger wires around on it, as long as you do not run the engine.<br /><br />Trigger works in series. You will lose 2 cyls or 4 cyls.<br /><br />Stator, you will lose all 4 cyl's.<br /><br />Powerpack. 1 or more cyl's.<br /><br />But for piece of mind, move the trigger wires to be sure. <br /><br />Email me for one on one if you need it.<br /><br />TMD

 

[greasemonkeyozi]

Re: 88' Merc 80hp 3cyl intermit rough idle

Sounds like a typical power pack problem to me. Hey, say that 5 times fast.

 

[Dallenx]

Re: 88' Merc 80hp 3cyl intermit rough idle

Thanks all.<br />I replace the switchbox (power unit) with a used one and now Everything works.