Having problem with Mercury 2.5L planeing, trigger out of spec, opinions

**Fishwhisper** · 06-02-2022, 08:49 PM

This weekend my 2002 Mercury 200 hp Carbed motor 0T566776 decided it didnt want to plane off. It idled and fast idled (upto 1300 rpm) fine. But would bog and start running rough when I applied throttle to plane, sometimes it would just loose all power but not cut off.

When i got home I broke out my service manual and tested the stator as best I could, checked continuity and static ohms, was in spec. I have ordered a DVA for a more thourough testing soon.

Check the trigger, it measures out of spec low, the three pairs measure approx 606 ohms, 676 ohms and 768 ohms. Book says should be 1100-1400 ohms. I did check it while moving the timer arm and moving the wires around, not much difference.

Then i used a timing gun at idle, light showed spark on all plugs and far as i could tell, fairly consistent. BUT, when I hooked it up to cylinder 1 and shined the light at the timing mark, it was sporadic, it would show 4 degrees BTDC then it was on the 462 mark are it was just flashing a black section of the flywheel, and then back to 4 degrees. So it seems to me the timing is jumping all around.

My question is, am I right that this would be a bad trigger? Is the low ohm readings usually indicative of a problem? When i recieve the DVA I plan to test the stator, trigger and CDM modules better, but just trying to get an idea right now.

**rgsauger** · 06-02-2022, 09:53 PM

Sounds like you have done a good job of troubleshooting it. With the ohms being half of what they should be and the timing jumping around like that, the trigger surely seems suspect.

**LakeFever** · 06-02-2022, 10:12 PM

If budget allows freshen it all; stator, trigger, and both switch boxes. This is a 20 year old motor. Keep the parts as back ups. I carry switch boxes on board after going through hell trying to figure out a similar issue. It wrecked three good days of boating for me that i could have prevented by spending 500 bucks or so that i ended up spending anyways. Just my 2 cents

**25two.stroke** · 06-02-2022, 10:13 PM

DVA the trigger output cranking when you get the DVA, that will tell you.

**Fishwhisper** · 06-02-2022, 10:32 PM

Thanks for the responses: I am going to wait for the DVA to properly test all the components just to make sure, could always be more than one component. LakeFever, sounds like a good idea, it did sorta ruin a four day trip. The boat ran at idle and fast idle, upto about 6 mph, but that made for some slow fishing and couldnt really move far. It would have been nice to have some replacements on hand. Its a CDM motor so no switch boxes but will probably keep a couple of CDM modules on hand, and a trigger and stator. Was also thinking may be a good time to replace the plug wires also, everything on the motor is original.

**LakeFever** · 06-03-2022, 07:20 AM

Im not an expert by any means but in my first v6 with a similar issue i did the dva thing and had good’ish readings which prolonged my struggle as i looked into other possibilities. Then In the end the stator swap solved it but this was after new switch boxes, rectifier, ignition switch and completely going over all the wiring and grounds. Theres a wire from the ignition switch that needs to have zero ground to it when the switch is open iirc its the black and yellow one. Might want to search how to test ignition switch and try that too.

hope you get it sorted out

**OnPad** · 06-03-2022, 11:12 AM

If your trigger is misfiring, it will mess with your injector timing also.
Your on the right track getting a dva for testing. I think you will find a limited amount of tests available for your module, I believe bias test. Also test your coils for good measure.
We just went through a similar problem with 80Grady. His post is titled intermittent loss of power, on page 2 of technical discussion. Mr Gradys engine was 1st gen cdm, and turned out to be injector drivers in ecu, but there's some troubleshooting tips in that thread. Good luck!

**tlwjkw** · 06-03-2022, 11:27 AM

2002 Mercury 200 hp "Carbed" motor

**OnPad** · 06-03-2022, 11:29 AM

Originally Posted by tlwjkw

2002 Mercury 200 hp "Carbed" motor

My bad, I wasn't paying attention!

**tlwjkw** · 06-03-2022, 11:42 AM

i do that myself.. i blame my wife for distractin' me with her honey-do's from a coupla years ago........

**25two.stroke** · 06-03-2022, 12:31 PM

Originally Posted by LakeFever

Im not an expert by any means but in my first v6 with a similar issue i did the dva thing and had good’ish readings which prolonged my struggle as i looked into other possibilities. Then In the end the stator swap solved it but this was after new switch boxes, rectifier, ignition switch and completely going over all the wiring and grounds. Theres a wire from the ignition switch that needs to have zero ground to it when the switch is open iirc its the black and yellow one. Might want to search how to test ignition switch and try that too.

hope you get it sorted out

Originally Posted by tlwjkw

2002 Mercury 200 hp "Carbed" motor

Yes. All keep in mind this is an 02 that does not have switchboxes. Or the conventional ignition that 95% of us use on our 2.0/2.4/2.5s

**PanRonnie** · 06-03-2022, 01:13 PM

You might luck out on ebay with a complete ignition system if you keep your eye out
Since not many motors were made with this system, resale value probably is not high