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1989 50hp 3 Cylinder Trigger question

B

BAS

Member
I have a 1989 50hp Merc 3 cylinder 2 stroke and it has no upper end of throttle power. I have eliminated fuel as a problem after replacing or rebuilding every fuel component from tank the carbs.
It gets to about 1500-2000 rpm and goes no higher. It doesn't stumble or die just will run at lower rpm.
I was troubleshooting the ign system and started with a visual inspection of components. Flywheel looked good and was installed correctly. Stator was clean, crack or break free, when I looked it the trigger I noticed what appeared to be a built in in-line fuse holder that was empty on the top of the trigger:confused: I checked the wiring diagrams and parts lists and couldn't find anything. Does anyone know if this is a fuse or nothing?
If I can eliminate this I will move to visually checking the rest of the ignition system and them testing individual components. I like to do these type of things in a systematic way and would like to rule out things as I see them before moving to the next component down the line.
Thank you

Merc Trigger.JPG
 

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There's no fuse in the trigger circuit. More likely is a bad stator. Do resistance checks on the high-speed and low-speed windings and I'll bet you find the hi-speed side is out-of-spec.

If you're not finding anything wrong, you'll need to pick up a DVA tester and check ign voltages while the motor is running.

http://www.marineengine.com/products/accessory.php?in=1329773

Heres a link to CDI Electronics troubleshooting info, which should help:

http://issuu.com/cdielectronics/doc...t.xml&backgroundColor=000000&showFlipBtn=true

The 3-cyl ADI section starts on page 80.

HTH...........edx
 
I tested the stator hi and low for resistance
Lo-Blue- 6000 ohm (Spec 5800-7000)
Hi-Red- 154 (135-165)

Trigger (Spec 800-1400 for all)
Black and:
Purple-1.265k (1265)
White-1.242k (1265)
Brown-1.4m randomly jumping back and forth up to 1.58m
I'm thinking trigger. Thoughts?
 
BAS said:
I tested the stator hi and low for resistance
Lo-Blue- 6000 ohm (Spec 5800-7000)
Hi-Red- 154 (135-165)

Trigger (Spec 800-1400 for all)
Black and:
Purple-1.265k (1265)
White-1.242k (1265)
Brown-1.4m randomly jumping back and forth up to 1.58m
I'm thinking trigger. Thoughts?
Click to expand...

Sounds like you may have found your problem! I'd expect that with a trigger reading like that, the engine would have been dropping a cylinder, which would be very noticeable at idle.

The trigger wires are somewhat fragile and get deteriorated with age; I wouldn't be surprised if yours has a break in it somewhere. I had a 50hp 4-cyl with a bad trigger wire close to the trigger, was able to splice in a good piece of wire and fix it.

Fortunately new triggers are cheaper than new stators!
 
One of the perplexing issues was the fact it idles and runs to the 1500-1800 range so smoothly. Even when it wouldnt "throw over" to plane it still ran well. No stumbles bumbles spits stalls or backfires so typical in ignition issues. Its been a frustrating diagnosis. Ill report back the results on the trigger.
 
Do these checks on a trailer backed into lake....Check spark with timing light as RPM is increased...if it is not dropping any spark, squirt some premix fuel into carbs to see if it picks up. If it boggs down that will eliminate a reed/carb problem and it confirms electrical problem. You will need a DVA adapter and check the high speed stator output at pack as it should be 180v +. If not the stator high speed is bad, if it is correct then the rectifier in switchbox is bad and not flipping to high speed side of box.
 
Should I not replace the trigger? At least yet? My assumption was being the ohms on the brown wire on the trigger were so far out of spec that this is at least one of the problems.
 
Where Im struggling is, if I test the engine with a known bad trigger, wont the readings of the stator test be affected? Dont I need to install a new trigger then test the blue and red leads with a DVA after?
Thanks for all the help. I would like to avoid costly mistakes.
 
if I test the engine with a known bad trigger, wont the readings of the stator test be affected?
Click to expand...
Nope... 2 separate systems

Dont I need to install a new trigger then test the blue and red leads with a DVA after?
Click to expand...
Nope....see above.
If you have spark on all three now the trigger is working, the timing light will let you see if one cylinder drops out as RPM/voltage increases. Also make sure timing is advancing as trigger moves..
 
Ok, I think it's only fair I post up findings! Everyone was right and sort of right. 1-The trigger was bad, I did a simple test recommended to me by CDI Tech Support and the trigger was DOA. The stator was good, however, something looked fishy and I found it to be the wrong stator for the engine... I replaced the powerpack because it was available and I figured for the cost just do it. Lastly the jet in the lower carb bowl was messed up.
Thanks for the support. And I hope that others will post results on their projects also.
 
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