Question for the pros

[IOU1]

I have a 1990 150hr mariner engine and I have one cylinder that is not giving any spark its number 3. The first test I done is switched the green wire from number 5 cylinder to the number 3 cylinder now I have spark. So I thought it was the coli that was bad and I have replaced the coli to this cylinder. Tested it again and still I don’t get any spark to this cylinder with a new coli. I have disconnected the black/yellow wire (kill wire) from the switch box just to see if I would get any spark cranked the engine up still no spark. But when I shut off the key switch now with the key switch off this cylinder number 3 gives out good spark? Any suggestions from the pros?

 

[WillyBWright]

Re: Question for the pros

The problem is in the other switchbox. The cylinders kinda fire in pairs, not at the same time but 180 degrees off. Current goes thru both switchboxes to fire the pair. Depending what the polarity of the magnet in the flywheel is as it passes the trigger determines which way the spark goes. Turning off the key is triggering a spark. The point is it sparks. That switchbox is good. The return path that completes the electrical circuit is bad in the other switchbox.<br /><br />Then again, I could be wrong.

 

[Hooty]

Re: Question for the pros

Hey oweya one,<br />I'm missin' something here. <br />You saying that with the key switch off you got spark?<br /><br />c/6<br />Hooty

 

[Hooty]

Re: Question for the pros

Ohhh, okay. Thanks Willy, now I'm understandin' what he was sayin'.<br /><br />c/6<br />Hooty

 

[IOU1]

Re: Question for the pros

Yes I took off the kill wire yellow/black shut off the engine but it still kept on runing. I checked out the number 3 and had spark on this cylinder? What do you think is wrong?

 

[achris]

Re: Question for the pros

If you didn't remove the kill wire from the other switch box then Willy suggestion is the one I'd go with. The other possiblity is the oil warning module. Is there a second green wire on that post? If so, it goes to the oil warning module and it the engine speed reference for it. I have seen them shutdown the coil. <br /><br />Chris............

 

[IOU1]

Re: Question for the pros

Ok this is what I have done by the way I have twin 150's mariner engines. I pulled off the switchboxes from the good running engine and put them both on the bad running engine. Must of been one of the switchboxe that was bad. Now I get good spark on all cylinders. One question that I have, is I'm using a spark tester for all cylinders. On bank 1,3,5 the spark tester dosen't give out good spark hooked up to the spark plug. But when I ground it to the engine block I get a real good spark? Any thoughts?

 

[KCLOST]

Re: Question for the pros

??????? Hmmmmm,<br /><br />This not so good spark on 1,3,5 is with known good swithcboxes???<br /><br />Are you sure you have both switchboxes grounded? There is a ground lead for both!<br />You can also replace the plugs, but make sure you ground the boxes first, if not you could fry them.<br /><br />A weak spark on one bank can be an indication of a stator problem... <br /><br />For a quick test (after both boxes are grounded) switch the red/blue wire from one box with the red-white/blue-white wire from the other. What you are doing is switching the voltage leads being sent to the boxes from the stator. If the weak spark condition moves to the other bank it's the stator causing this. But if it runs fine with all cylinders firing, that may not be a problem.<br />Let us know.