Stator seems OK ,coils don't

[doctoroldsmobile]

I have a 1988 merc 135 V6. I'm only getting about 4400-4500 rpm at WOT. So I decided to test the stator, trigger, coils etc.and if they checked OK, I'd do the Timing and Synchronization adjustments.<br /><br /> Well, the stator ohm readings don't seem right. I'm reading 2,400 ohms between the blue/white and red/white and the same between red and blue. The manual says they should be 5,400 to 6,200. Also, between the red/white and ground I'm getting 54 ohms same between red and ground. The manual says 125-175 ohms.<br /><br /> It sounds like the stator is going bad, probably the high (red) side. Am I on the right track or do they read lower than the book said normally?

 

[ODDD1]

Re: Stator seems OK ,coils don't

doc, usually ohms redings on these fall a little closer to specs than this..not saying it is bad, have seen many stators be technically out of spec and lead long lives....the fact that your high and low speed pairs read equal to each other is a good thing......normal test procedure is to check voltage output with a peak reading DC voltmeter, then if a prob is found, use the ohms test to verify the failed component....

 

[doctoroldsmobile]

Re: Stator seems OK ,coils don't

Thanks for the reply ODDD1, I think I need to get the FACTORY service manual. I'm using the Seloc manual currently. It says nothing about checking voltages. What readings should I look for?<br /><br />I also checked the resistance between the blue and blue/white and got about 2,000 ohms but the red and red/white only have about 150.

 

[doctoroldsmobile]

Re: Stator seems OK ,coils don't

Hello again, after reading an earlier post to Jersey13 from ODDD1 about checking the stator output voltages on the merc, I ran the test on mine.<br /><br /> At cranking speed there are 234 volts between the blue wire and ground and 234 volts between the blue/white wire and ground. Between the red wire and ground I'm getting 24 volts and the same between the red/white and ground. So I think the stator is OK. <br /><br />Next, I checked the spark to the plugs and numbers 1 and 2 didn't have any or very weak .Sounded like switchboxes but wait. Just for grins I switched the coil pairs between 1-2 and 3-4 and the problem moved to cylinders 3-4 so it looks like it's the two coils. Seems weird that they would fail as a side by side pair but the first rule I was taught about diagnostics was if a problem follows a component when you move it to a new location, the component is junk.<br /><br />Thanks for steering me in the right direction. This board is fantastic!