sick 150hp Mariner

[stocky]

Out on the boat over the weekend. Was cruising around for about 1-1.5h at about 3000-3500rpm I then decided to open her up a bit more to about 4200rpm when the engine just lost all power, still idled but really rough. Pulled the plugs, 5 wet and one dry so to me, obviously a electrical problem. Before limping back to the ramp I decided to beach the boat and have some lunch, kick back and consume some amber fluid. After approximately 2h decided to limp back to the ramp engine was fine. All cylinders running, idling smooth (for an old Mariner) with plenty of acceleration and ran for about 30 min at 4200rpm and it didnt miss a beat. Does anyone have any ideas of what could be the problem if I had to guess it is probably the unit ( cant remember the term) which supplies spark to the plugs and when it gets hot it is breaking down. The motor is a Mariner 150hp V6 85-86 model. Thanking all replies in advance.

 

[Down South]

Re: sick 150hp Mariner

It may have been starving for fuel. If it does this again try using the primer bulb. Make sure it's tight and see if it picks back up.

 

[stocky]

Re: sick 150hp Mariner

I would have thought that if it was starving for fuel that I would not have found 5 wet plugs and 1 dry. My thought is that at the time of difficulty I had spark to only one cylinder (the dry one).

 

[Down South]

Re: sick 150hp Mariner

Stocky,<br /> There is no way that engine will run on only one cylinder. I'm not saying you don't have an electrical problem either but if it's running like it's supposed to right now. Then trouble shooting a problem will be hard. <br /><br />Ok, if it gives you problems again, try the primer bulb. If that doesn't do the trick then try removing spark plug wires to see if any make a difference.<br />Another thing. Do you think your motor may have ran hot and went into the limp mode? Just something to think about.

 

[stocky]

Re: sick 150hp Mariner

Thanks Down South.<br />In regards to the engine going into limp mode I dont think that a model this old has that feature. You are right in saying that the problem maybe difficult to locate if it is occurring every now and then. It looks as if I may have to play the parts game and replace things such as fuel filter, spark plugs etc. If I have time during the week I might get my miultimeter on the job and start checking circuits and locate possible an area where the electrical circuit is not quite to specification.

 

[stocky]

Re: sick 150hp Mariner

I have gone through the diagnosis sequence from the manual and it appears the problem is a dud stator. To help others in this situation I will give my results. These measurements are made from wires to the switchbox.<br /><br />Trigger test<br />Wires<br />Brown (no yellow sleeve) and White (with yellow sleeve 1351 ohms (to specification)<br /><br />White (NYS) and Brown (WYS) 1245 ohms (TS)<br /><br />White (NYS) and Violet (WYS) 1294 ohms (TS)<br /><br />Trigger OK<br /><br />Stator test<br /><br />Red to ground 130 ohms (To Specification, TS)<br />Red/White to ground 130 ohms (TS)<br />Brown/White and Red/White 5700 ohms (TS)<br />Brown and Red 9000 ohms (Not to Spec.)<br /><br />Stator stuffed.<br /><br />Hope this info helps someone in the future.