1992 Merc 150 V-6, firing on 3 cylinders

[verojoe27]

I ran this engine 2 weeks ago and it ran perfectly. Today, I started it up and it sounded a little sluggish and idled roughly. It would die when I accelerated under power. Brought it back home and let it idle with the muffs on. I pulled the plug wires off one by one when it was idling and the tone of the engine changed only when I pulled off the left side spark plug wires. The head on the left side of the engine warmed to operating temperature, but the right side was still at room temperature. The water pump was working, but the stream was weak. I think that the 3 right sided cylinders are not firing and need to know how to test exactly what is wrong. Any helpful comments would be appreciated. Thanks, Joe.

 

[Laddies]

Re: 1992 Merc 150 V-6, firing on 3 cylinders

With a DVA ck the red and red white wires voltage should be 30+ and the blue and the blue white should be 180+ without a DVA swap the red, red white wires and the blue, blue white wires if you have spark on the other side it's the stator if it stays on the same side it's probaly the switch box--Bob

 

[Barnacle_Bill]

Re: 1992 Merc 150 V-6, firing on 3 cylinders

Wouldn't a bad trigger cause one side to go out?

 

[rodbolt]

Re: 1992 Merc 150 V-6, firing on 3 cylinders

no<br /> the trigger fires in pairs. I think he lost a stator or switchbox. the test laddie gave him will isolate it.

 

[KCLOST]

Re: 1992 Merc 150 V-6, firing on 3 cylinders

Those wires you need to switch are connecting to the top of the switchboxes... Switch them from one to the other and retest...<br /><br />let us know...

 

[verojoe27]

Re: 1992 Merc 150 V-6, firing on 3 cylinders

Sorry laddiesservice, I'm kind of confused about your message. I have a volt-meter, but I am not sure exactly where the wires you are talking about are? I know where the stator is, but I have no idea where the switch box is. And I assume that I do the voltage check with the engine idling? Any help clearing up my confusion would be appreciated, Thanks, Joe.<br /><br />P.S. I have done other mechanical work on this motor, but have never done any major electrical work on it, so I know very little about how it works. Please be specific about where the wires I am to test are located. Thanks!

 

[Laddies]

Re: 1992 Merc 150 V-6, firing on 3 cylinders

Joe, the wires that I am talking about are from the stator and are attached to the swictch boxs ( 2 boxs 3' by 7") and a standaerd volt meter won't work--Bob

 

[verojoe27]

Re: 1992 Merc 150 V-6, firing on 3 cylinders

laddiesservice, I think I know what you are talking about now. Due you mean that I should swap the 2 red/white wires going to the outer switch box with the 2 red wires going to the inner switch box and swap the blue/white wire going to the outer switch box with the blue wire going to the inner switch box? There is another red/white(a total of 3) wire going to the outer switch box that comes from another wiring harness. Do I move the 3rd red/white wire over to the inner switch box too. Thanks, and sorry about all the annoying little questions, Joe.

 

[Laddies]

Re: 1992 Merc 150 V-6, firing on 3 cylinders

Yes,I think that the other R/W wire is a idle stabiliser, but don't have a wiring diagram to check for you, I guess that could be a problem also so test it with it unhooked--Bob

 

[verojoe27]

Re: 1992 Merc 150 V-6, firing on 3 cylinders

The 3rd red/white wire is a idle stabilizer. The idle stabilizer is connected to the outer switch box, which runs the left side 3 cylinders (these are the ones that are firing). If I unhook the idle stabilizer, should the 3 cylinders that are firing now stop firing if the idle stabilizer is working properly? Thanks, Joe.

 

[verojoe27]

Re: 1992 Merc 150 V-6, firing on 3 cylinders

I unhooked the idle stabilzer and idled the engine and nothing changed. I swapped the wires from the outer and inner switch box and still no change-- the left 3 cylinders still are the only ones firing. Does this mean the problems one of the switchboxes? Thanks, Joe.

 

[icecold1]

Re: 1992 Merc 150 V-6, firing on 3 cylinders

ive got the exact same problem with my 86 merc 200 and after a new switchbox on the non fireing side still no spark,i should have swapped the boxes and then i'd still have 200 bucks as the first one must not have been bad.right now in the process of getting the flywheel off(waiting on the dealer for the puller)as the stator must be on the blink.i too was told mostlikly isent the trigger but i'm new to boat repair so i'm not sure of anything <br />good luck<br />pete

 

[KCLOST]

Re: 1992 Merc 150 V-6, firing on 3 cylinders

Yes, it's the switchbox or the coils for those non-firing cylinders.. You can switch the coils that aren't firing with ones that are, to confirm and make sure they are not the culprit...