Weird spark rectifier problem merc 150...

[boattoy]

Im working on a mercury 150 outboard(1985) and im stumped. It sat for 2 years(ran fine before it sat). My buddy gave his boat to a relative and the guy did some work to it(spark plugs,ignition switch) and got it started and it wouldnt rev above idle(idles fine) and doesnt charge. I thought i had it figured out when i pulled the wires off the rectifier and it ran great, revved up and idled perfect. So i bought a new rectifier and as soon as i hooked up the wires again same problem. there are 4 wires. One red, 2 yellow and one gray that hook up to it(3 post rectifier). anyone know what it might be? is there a chance he wired the ignition switch up wrong?

 

[Traceyh]

Re: Weird spark rectifier problem merc 150...

The Red wire goes to the battery from the rectifier to charge.
The two yellows come from the stator to the rectifier supplying AC voltage to be rectified. The gray wire goes to the tac.

 

[j_martin]

Re: Weird spark rectifier problem merc 150...

Im working on a mercury 150 outboard(1985) and im stumped. It sat for 2 years(ran fine before it sat). My buddy gave his boat to a relative and the guy did some work to it(spark plugs,ignition switch) and got it started and it wouldnt rev above idle(idles fine) and doesnt charge. I thought i had it figured out when i pulled the wires off the rectifier and it ran great, revved up and idled perfect. So i bought a new rectifier and as soon as i hooked up the wires again same problem. there are 4 wires. One red, 2 yellow and one gray that hook up to it(3 post rectifier). anyone know what it might be? is there a chance he wired the ignition switch up wrong?

Here's the hardest thing I had to get into the minds of field engineers I was training.

1. You walk up to a running machine
2. You do something to it.
3. It now does not run.

The problem is what you did to it.

For one thing, there's different ignition switches. This one both powers a key on circuit (when on) and grounds a kill circuit. (when off) If those functions get crossed or mixed up, serious trouble follows.

 

[boattoy]

Re: Weird spark rectifier problem merc 150...

Well the red wire is always hot key on or off so i think thats ok. What i dont get is why it doesnt rev up at all when i hook up the yellow wires. are the two yellow wires supposed to be seperate? There is no resistance between them(connected). what color wire turns on the field for the charging circuit? are there any online wiring diagrams for the quicksilver throttles? why does the charging circuit cause the motor not to run?

 

[j_martin]

Re: Weird spark rectifier problem merc 150...

It's time to acquire or make a DVA, and test the stator output to the switchboxes, both with the rectifier connected, and disconnected.

It's possible you have a cross-connection between the battery charging and charge coil windings in the stator.

hope it helps
John

 

[Traceyh]

Re: Weird spark rectifier problem merc 150...

Well the red wire is always hot key on or off so i think thats ok. What i dont get is why it doesnt rev up at all when i hook up the yellow wires. are the two yellow wires supposed to be seperate? There is no resistance between them(connected). what color wire turns on the field for the charging circuit? are there any online wiring diagrams for the quicksilver throttles? why does the charging circuit cause the motor not to run?

There is no "field" circuit on these machines. There are permanent magnets in the flywheel, and their magnetic flux passes through the windings inducing voltage in the charge coils. The voltage induced is AC voltage, that must be rectified to DC voltage to be used by the system. If the ignition circuit is battery supplied voltage, then a bad rectifier will usually cause a low voltage situation while running causing the ignition to not function properly.

 

[j_martin]

Re: Weird spark rectifier problem merc 150...

There is no "field" circuit on these machines. There are permanent magnets in the flywheel, and their magnetic flux passes through the windings inducing voltage in the charge coils. The voltage induced is AC voltage, that must be rectified to DC voltage to be used by the system. If the ignition circuit is battery supplied voltage, then a bad rectifier will usually cause a low voltage situation while running causing the ignition to not function properly.

Ignition is not supplied by battery, but by separate "charge coils" in the stator. They share the same iron core.

 

[Faztbullet]

Re: Weird spark rectifier problem merc 150...

A decayed or broken stator wire or a shorted stator can cause this....

 

[boattoy]

Re: Weird spark rectifier problem merc 150...

Im starting to think its the stator. Maybe when the yellow wires are hooked up it shorting the rest of the stator. The two yellow wires are pretty corroded. Where do you purchase a flywheel puller?

 

[boattoy]

Re: Weird spark rectifier problem merc 150...

alright... i tried using an ohm meter on he stator leads and got about 120 ohms on the high and low output (blue and red) and about 170 ohms on the yellow wires. checking ohms to ground. I looked up how to test it and it supposed to be like 1500 and 750 or something like that. Also serial number is 6569759. i cant seem to figure out what motor it is. none of the serial number ranges seem to fit it. need to know how to ohm the stator properly unless i did it right and its just bad.

 

[Dave1027]

Re: Weird spark rectifier problem merc 150...

Do the DVA test.

Once you get it figured out you might ask a boat mechanic if you can trailer the boat over to his shop and have him pop the flywheel off for you. Give him a 12 pack of beer for his trouble.

 

[boattoy]

Re: Weird spark rectifier problem merc 150...

dva meter costs the same as a new stator...

 

[roncoop75]

Re: Weird spark rectifier problem merc 150...

dva meter costs the same as a new stator...

I built mine for just a few dollars at radio shack. There are plans on this site in the electrical forum. DVM's are also cheap, you don't need a fancy one either. Way cheaper than a new stator.

 

[boattoy]

Re: Weird spark rectifier problem merc 150...

do you know the link to the thread to build one for cheap? also what is the thread size and pitch for the puller? is it 1 1/2-16? I want to start by checking the wires. I bet one is corroded and shorting out.

 

[boattoy]

Re: Weird spark rectifier problem merc 150...

FIXED!!(so far haha). Yellow wires were shorting to ignition wires. Installed a new CDI stator and it runs great and charges.

 

[boattoy]

Re: Weird spark rectifier problem merc 150...

Got a couple more questions. I hooked up the fish finder which has a built in voltage gauges and it runs at about 13.5 volts at idle and up to 16.8 at 3000- WOT(never went above that). im assuming its high because the motor only has a rectifier that converts to DC and doesnt actually regulate voltage. Is this correct? also the overheat alarm went off ONCE. I pulled a tube around for about 10 minutes and it tripped. I let it idle for a sec then shut it off and started it right back up and it went away for the rest of the day pulling a tube. I was kinda lugging it a little at 2800-3000 rpm when it tripped. seemed to run better at about 3500 so thats what i did and didnt have any issues. Water pressure was fine. a couple psi at idle and 10-15 above 2000rpm. could it have gotten an air pocket or something causing this? how hot does it have to be for it to trip?

 

[Dave1027]

Re: Weird spark rectifier problem merc 150...

Got a couple more questions. I hooked up the fish finder which has a built in voltage gauges and it runs at about 13.5 volts at idle and up to 16.8 at 3000- WOT(never went above that). im assuming its high because the motor only has a rectifier that converts to DC and doesnt actually regulate voltage. Is this correct?

That's normal for unregulated motors. The battery becomes the regulator and tops out at about 16 volts.

 

[j_martin]

Re: Weird spark rectifier problem merc 150...

FIXED!!(so far haha). Yellow wires were shorting to ignition wires. Installed a new CDI stator and it runs great and charges.

It's possible you have a cross-connection between the battery charging and charge coil windings in the stator.

Like I said
John