Weak to no spark on a in line 4 cyl Sea Ray 100 HP Mercury/Mariner

[dwulfe]

I have a 100 hp 0B209468 thru 0G437999, Sea Ray version of Mercury Mariner a 1988 in line 4 cylinder model. It has a weak spark on only one of the 4 cylinders with the plugs in. With the plugs out at the boat ramp I thought I had a weak spark on 3 cylinders. By weak I mean it only can jump about 1/16" - 1/8".

Anyway, in CDI Electronic's trouble shoot guide it lists resistance readings.
( link http://cdielectronics.com/Portals/0/installsheet/114-5772.pdf )

1. Do those need to be performed with the wires disconnected from the switch box? My numbers are off pretty much with them connected.

2. Also if it was a kill circuit issue I should not see any spark, true?

3. Do you know of any cheap radio shack dva meters that can read the short voltages pulses and do the wires need to be disconnected from the switch box when reading? I also assume the motor needs to be cranking at at least 250rpm when taking the readings, true?

Any help would be appreciated.
Thanks

dwulfe in Cincy

 

[zorak]

Re: Weak to no spark on a in line 4 cyl Sea Ray 100 HP Mercury/Mariner

Resistance readings need to be done with the wires disconnected. you are correct about the kill switch circuit. As far as a dva meter is concerned any digital multimeter will do ,the tricky part is the DVA adapter.thay are 30 to 60 bucks online.I built one with a few parts from radioshack .It only consists of 1 resistor,1 diode and 1 capacitor.Radioshack didn't have the cap,but i took one out of a disposable camera flash. do a search on dva adapter on this forum os buy one.You really cant propery troubleshoot without one.Resistance readings can be pretty close to spec but 1 shorted winding in a stator or trigger will drastically cut the voltage output which is what you would be testing with a dva adapter.

 

[Dave1027]

Re: Weak to no spark on a in line 4 cyl Sea Ray 100 HP Mercury/Mariner

DWolfe,

What is your motor doing? Is it missing? Hard to start?

 

[dwulfe]

Re: Weak to no spark on a in line 4 cyl Sea Ray 100 HP Mercury/Mariner

Thanks Zorak

 

[Faztbullet]

Re: Weak to no spark on a in line 4 cyl Sea Ray 100 HP Mercury/Mariner

stator......

 

[dwulfe]

Re: Weak to no spark on a in line 4 cyl Sea Ray 100 HP Mercury/Mariner

Dave- here is the saga. Motor ran fine 1st few times out this season. Then it began to be hard to start. Would pull the plugs and crank it over. Would get a lot of fuel spray out. Dry off plugs and reinstall and it would start but not idle. Would run OK from 2000 rpm to WOT. The fuel pump bulb also did not feel tight when pumped. Rebuilt carbs with new needles and gaskets and cleaned the seats. Started right up in the drive way and idled smooth at 900rpm after the carb rebuild. Trailed it 15 miles and put her in the water and it would not start. Not even one POP or puff of smoke.

The last test was a few days ago with the plugs in and only showed a spark off #2 cyl (from top) of about 1/16". As I recall when I tested at the boat ramp with the plugs out I saw a small (1/16") spark off 3 of 4 cylinders. I'm thinking the faster it spins the more juice it puts out but it's still not enough to get more than 1/16" spark gap.

 

[dwulfe]

Re: Weak to no spark on a in line 4 cyl Sea Ray 100 HP Mercury/Mariner

I got resistance and home made DVA readings with the wires removed from the switch box.

Stator blue to blue/white - 1320 ohms - 21 Volts
Stator red to red/white - 120 ohms - 24 Volts

Trigger purple to white 900 ohms - 4 volts
Trigger brown to black 940 ohms - 4 volts
All trigger wires to ground were open. Voltage not tested.

Even though the DVA is home made I think it is accurate to 10% or so and I have a real low ohm and voltage reading between the blue and blue/white stator wires. So, I assume the stator is bad, true?

Is there anything else that should be checked that could have caused the stator to breakdown? I'd hate to put an expensive part in and blow it right up.

dwulfe

 

[zorak]

Re: Weak to no spark on a in line 4 cyl Sea Ray 100 HP Mercury/Mariner

I checked the cdi website to see what your dva readings should be.In my opinion i think the stator is toast but the trigger coils are ok.I had to do the same test on my ignition system and the stator readings were well inline with what cdi says it should be where as yours are very low. As far as anything else causing a stator to go bad i have read that some poeple will go ahead and replace their stator, triggers and switchbox at the same time. My switchbox was bad and it didn't fry the stator. One other thing i would test is the rectifier as well. Pull the yellow wires off of the regulator and see if its bad as well. Check dva voltage with the yellow wires disconnected, just make sure they arent touching any metal. They are notorious for shorting out and could cause stator damage or possibly affect the stator voltage output.

 

[dwulfe]

Re: Weak to no spark on a in line 4 cyl Sea Ray 100 HP Mercury/Mariner

Thanks Zorak,

I did pull the yellow wires from the rectifier. Got the same 20 v off the high side where it should be around 180.

Now the challenge of removing the flywheel - it's on real tight - been soaking the shaft with oil. Looks like I will be ordering a mercury puller or calling around to see if I can get a shop to pull it for me (if I buy their parts). Problem here is all the shops have a 2-3 week service back log.

I also can't find the voltage regulator. Mine has two gadgets that look like small starter solenoids mounted next to the switchbox.

Photo - http://home.fuse.net/wulfe/sea-ray_1988_100HP_1.jpg

 

[Dave1027]

Re: Weak to no spark on a in line 4 cyl Sea Ray 100 HP Mercury/Mariner

I think those are the up and down solenoids for the power tilt/trim.

Also, I don't think the standard 9 amp motors come with a regulator.

 

[zorak]

Re: Weak to no spark on a in line 4 cyl Sea Ray 100 HP Mercury/Mariner

Yea,your gonna need a puller as you cant beat on the flywheel and you sure don't want to mess up the end of the crankshaft.I am thinking of building one for myself to have laying around as i am lucky enough to have access to a metal lathe.

 

[Dave1027]

Re: Weak to no spark on a in line 4 cyl Sea Ray 100 HP Mercury/Mariner

My dealer let me borrow a puller because I buy the parts from him. I gotta say, it was a hell of a job. I thought something broke when the flywheel finally broke loose. It took me and a buddy both pulling on a long handle breaker bar. Not fun.

 

[dwulfe]

Re: Weak to no spark on a in line 4 cyl Sea Ray 100 HP Mercury/Mariner

I drug up to a Mercury marine dealer that stock a lot of parts. The parts guy fixed me up - had one of their mechanics pop it off in 15 seconds - looked easy with the right tool and that impact wrench.

Now the problem is my motor was made with a low amp stator that did not need a regulator, that has been superseded by a 16 amp stator kit that includes a bunch of adapters and connectors and a required voltage regulator for $546.25.

I guess if I look at it as an upgrade with more amps and a regulator it's not too bad, plus I called the parts guy back to verify that the kit had instructions which it does. He also offered it to me for about $75 less cause it was unwanted inventory and not normally stocked.

 

[Dave1027]

Re: Weak to no spark on a in line 4 cyl Sea Ray 100 HP Mercury/Mariner

Edit to add: Oops. I misunderstood. Yeah, get the cdi unit.

 

[zorak]

Re: Weak to no spark on a in line 4 cyl Sea Ray 100 HP Mercury/Mariner

Thats awful high for a stator i think.I would price one from cdi as i understand thay are superior to the OEM ones.I can get a stator for my classic 50 for less than $200 bucks.

 

[dwulfe]

Re: Weak to no spark on a in line 4 cyl Sea Ray 100 HP Mercury/Mariner

Hey the boat is 22 years old - In an ideal world I would put OEM in it but a $270 price difference (which would include and upgrade to a regulated 16 amp charging circuit) is too steep for me. I will be getting a CDI 8778 version.