Logo
FULL SITE MENU

Yet Another Merc 40 2 Stroke With No Spark

R

RickM46

Regular Contributor
This post is a continuation of another post of mine - Yet Another Merc 40 2 Stoke 4 Cylinder won't idle http://www.marineengine.com/boat-fo...nother-Merc-40-2-Stroke-4-Cylinder-won-t-idle In that thread, the fellas on the forum determined that the carbs needed cleaned. I haven't done the carbs yet. I thought I would double check spark.

Now, a new problem. After many attempts, my '92 Merc 40 2 Stroke 4 Cylinder won't start or even bark. I was puzzled. I thought I would again verify I had spark. Used a Lisle 20610 spark tester and found I now have no spark on all 4 plugs. Tested the spark tester on my Kawasaki John Deere with electronic ignition and it gave off a nice orange spark.

Any instructions of what to check upstream from the plugs? I have included pictures of my electrical panel. I have a multi-meter.
 
Last edited:
Well, no responses; can't says I blame anyone - I am no electrical guy - looking at the electronics box, a line from the movie Pearl Harbor: 'Lots of switches and stuff'.

Now, I have reverted to RTFM mode and am closely reading the shop manual on testing the Stator, Trigger, Mercury tilt switch. There is no test for the switch box. I am going to bypass testing the 4 ignition coils as I don't think all 4 could go bad at once. I have a multi meter and will give it a shot.

From my picture of the electronics box, I don't know what the box to the left of the yellow fuse is; I don't know what box is under the grey foam packing; anyone know?
 
Load test your battery.----Then take starter apart for inspection.-----Most responses to this will say ---- " my starter cranks just fine "
 
racerone, thanks for the tip; will load test the battery; it has been taking a beating trying to get the outboard to start along with beating up the starter; as you mentioned above, the starter turns over with no hesitation; so having a dragging starter will deprive the rest of the ignition system?
 
Did tests on the stator, trigger, mercury trim switch, coils and found the stator was out of spec. Now, will search for a replacement stator, flywheel holder, flywheel puller.

STATOR test: disconnect all stator leads from switchbox, then test:
Leads:
Blu and Blu/Wht -------- Factory spec: 5700-8000 Ohms; ---- My result: 18,708
Red and Red/Wht -------Factory spec: 56-76 Ohms ------------My result: 95
Blu and Ground ---------Factory spec: No Continuity----------- My result: No cont.
Red and Ground ------- Factory spec: No Continuity ------------My result: No cont.

TRIGGER, disconnect all trigger leads from switch box, then test:
Leads:
Brown and Wht/Blk-----Factory spec: 700-100 Ohms ----------My result: 824
Wht and Violet ---------Factory spec: 700-100 Ohms-----------My result: 824

BLUE COILS (there are other stock colored coils: black, orange).
Disconnect plug lead to coil tower; test tower and pos lead:
Coil: Factory Spec: --------------My result:
#1 - 800-1100 Ohms ------------946
#2 - " ---------------------------- 954
#3 - " -----------------------------935
#4 - " -----------------------------929

TRIM MERCURY SWITCH:
Leads:
Black and Black/Yellow ------- Factory Spec: -----My result:
With lower unit down ----------No continuity ---- No continuity
 
Last edited:
Progress in getting to the stator: I bought flywheel holder tool Merc part# 91-52344 (from Amazon, Lisle model 23800) and flywheel puller Merc part# 91-73687A1 (from Ebay) and removed the flywheel. Used an 18" breaker bar and flywheel holder to loosen the flywheel retaining nut and removed it; used the flywheel puller and flywheel holder to pull the flywheel. Got the Merc part number off the stator: 398-81835A3 and will now shop for that stator.
 
Also, kudos to Tom T. at Marineengine.com; he helped in identifying the right CDI stator for my engine along with Susan at CDI - good people; deluged both with questions, prompt answers!
 
Here is an excerpt from the CDI Diagnostic Manual at http://www.cdielectronics.com/wp-content/uploads/2016/05/Tech-Guide-Digital.pdf -- good stuff. To further kill the subject, I ordered the Electronic Specialties 640 DVA adapter from Amazon to test voltage output from the stator.

Four Cylinder Engines1978-1998
Four Cylinder Engines Using a Single Switch Box and Four Ignition Coils
NO SPARK ON ANY CYLINDER:
1.Disconnect the Black/Yellow (or Orange) stop wire AT THE SWITCH BOX and retest. If the engine’s ignition now has spark, the stop circuit has a fault. Check the key switch, harness and shift switch.

2.Disconnect the Yellow wires from the stator to the rectifier and retest. If the engine now has spark, replace the rectifier.

3.Check the cranking RPM. A cranking speed of less than 250-RPM will not allow the system to spark properly. This can be caused by a weak battery, dragging starter, bad battery cables or a mechanical problem inside the engine.

4.Inspect and clean all engine and ignition ground connections.

5.Verify the correct flywheel is installed.

6.Check the stator resistance and volts with a DVA adapter output as shown below:
Flywheel with Bolted In Magnets.
Blue/Blue-White stator wires: OEM Ohms 5000-7000, CDI stator Ohms 2000-2400, DVA volts 180-400
Red/Red-White stator wires: OEM Ohms 125-155, CDI stator Ohms 45-55, DVA volts 25-100

Flywheel with Glued In Magnets.
Blue/Blue-White stator wires: OEM Ohms 3250-3650, CDI stator Ohms 488-662, DVA volts 180-400
Red/Red-White stator wires: OEM Ohms 75-90, CDI stator Ohms 28-32, DVA volts 25-100
 
CDI stator showed up today; first rate quality materials; heavy gauge windings, heavy gauge connector wires and connectors; fits into OEM flywheel with glued in magnets with tight tolerance; now to install but will go very slow to get wires routed right - tight spaces.
Tested the wires with my meter:
Blue/Blue-White stator wires: CDI stator Ohms spec 488-662, my CDI stator 582 Ohms
Red/Red-White stator wires: CDI stator Ohms spec 28-32, my CDI stator 29.6 Ohms

Would show pictures but Insert Image doesn't work.
 
Last edited:
Here are some pics; had to go to the 'Go Advanced' button and then click on 'Attachments' button; easy from there; the second pic shows the stator in my flywheel - very snug fit with almost zero clearance with the magnets.

One last thing; noticed a type of grease on the flywheel center collar and the end of the crankshaft; put there way back in '92 to allow removal of the flywheel; anyone know what type of grease that is so that I can replenish it???

IMG_0501.jpgIMG_0502.jpg
 
Last edited:
Thanks Jeff; but when I lifted the flywheel off the crankshaft, there were 3 things I saw:
1.The end of the crankshaft is not tapered and the flywheel center collar is not tapered.
2.A small vertical key (I think you would call it a key, rectangular solid) that fits into a slot in the crankshaft and a corresponding slot in the flywheel center collar.
3.A thin layer of a clear brownish grease on the crankshaft end and the flywheel center collar.

I am thinking the grease is there to prevent the flywheel from corroding itself to the crankshaft.
Any recommendations on the grease to use?? I was thinking wheel bearing grease.
 
Took the old stator off and compared to the new CDI stator; the leads on the CDI stator are incredibly longer than the stock leads; no surprise since the new stator has to accommodate many engines. Will have to shorten the leads as there is very little room in the electronics box. When I cut the new leads to length, are there any suggestions on where I can get new connector ends?
 

Attachments

  • IMG_0550.jpg
    IMG_0550.jpg
    52 KB · Views: 70
Last edited:
Success! Installed the new CDI stator, clipped the stator wires to fit the switch box posts; crimped eyelet connector ends to the wires and included shrink wrap and fastened them to the switch box posts; assembled the flywheel and cowl back to the motor; re-installed the starter motor; reconnected the battery.

Primed the heck out of the carbs; after 4 short bursts of the ignition while choking, the engine started and ran strong - even at idle and in gear in my tub. Restarted very easily with no choke. I think the old stator was slowly deteriorating and then provided no spark. It may be my imagination, but now it seems to run stronger and idle better than it ever has.

Kudos to Tom T. at Marineengine.com; he helped in identifying the right CDI stator for my engine along with Susan at CDI - good people; deluged both with questions, prompt answers!

As it turns out, there was nothing wrong with my carbs as I thought in a previous thread: http://www.marineengine.com/boat-fo...nother-Merc-40-2-Stroke-4-Cylinder-won-t-idle. While laboring under that mis-diagnosis, I emptied the main tank and insured there was no debris in it; bought new primer bulb and fuel line; took samples of gas from the bottom of the tank which showed no ethanol or water separation; drained the float bowls and refreshed with non-ethanol gas.

Many thanks to the fellas on the forum!
Happy Camper
 

Attachments

  • IMG_0564.jpg
    IMG_0564.jpg
    61.8 KB · Views: 85
,,," I think the old stator was slowly deteriorating and then provided no spark."

Correct. The electricity for the ignition is developed by that stator, so if it's spinning slowly it doesn't make a good spark.

Glad to hear you're up and running.

Jeff
 
Many thanks to fastjeff and racerone for advice.

One last thing, while focusing on the ethanol gas induced carb problem which was not the problem, I did find that the rubber fuel hose going from the enrichener solenoid to the upper carb had rotted and detached - fixed that and now both carbs get a squirt of fuel at choke time.
 
RickM46 said:
Did tests on the stator, trigger, mercury trim switch, coils and found the stator was out of spec. Now, will search for a replacement stator, flywheel holder, flywheel puller.

STATOR test: disconnect all stator leads from switchbox, then test:
Leads:
Blu and Blu/Wht -------- Factory spec: 5700-8000 Ohms; ---- My result: 18,708
Red and Red/Wht -------Factory spec: 56-76 Ohms ------------My result: 95
Blu and Ground ---------Factory spec: No Continuity----------- My result: No cont.
Red and Ground ------- Factory spec: No Continuity ------------My result: No cont.

TRIGGER, disconnect all trigger leads from switch box, then test:
Leads:
Brown and Wht/Blk-----Factory spec: 700-100 Ohms ----------My result: 824
Wht and Violet ---------Factory spec: 700-100 Ohms-----------My result: 824

BLUE COILS (there are other stock colored coils: black, orange).
Disconnect plug lead to coil tower; test tower and pos lead:
Coil: Factory Spec: --------------My result:
#1 - 800-1100 Ohms ------------946
#2 - " ---------------------------- 954
#3 - " -----------------------------935
#4 - " -----------------------------929

TRIM MERCURY SWITCH:
Leads:
Black and Black/Yellow ------- Factory Spec: -----My result:
With lower unit down ----------No continuity ---- No continuity
Click to expand...

I am a dummy when it comes to testing ohms, do you connect the two blues together and test them with the white. ????

Thanks
Milton
 
Milton, very easy to test Ohms; I an no electrical guy but learned a lot on how to test the electrical components of the engine; the shop manual guided me.

I have a multi meter that has many testing selections on its rotary dial and it has a red and a black wire with alligator clips on their ends; see pic of it below. You have to disconnect all 6 wires that originate from the old stator - Blue/Wht, Blue, Red/Wht, Red, 2 Yellow wires - from the their connections on the switch box. To do the test, you should disconnect the battery also. You do not have to remove the stator from underneath the flywheel. You connect one meter lead to the Blue/Wht wire, you connect the other meter lead to the Blue wire; you rotate the knob on the meter to the Ohm setting; turn on the meter and then read the Ohms number. In my picture below, the 2 rightmost wires are the Blu/Wht and the Blue wires same colors as those that originate from the old stock stator.

You have to find out the Ohms spec for your motor. My meter is a TekPower TP2844R found at https://www.amazon.com/Tekpower-TP2844R-Auto-ranging-Multimeter-Resolution/dp/B004YF0VEM.

attachment.php
 
Last edited:
Below is a drawing of my engine wiring

Check the ohms on the two wires Blue and red with meter set on the horse shoe looking symbol and got 16.8 ohms. ???

Tested the red wire to ground and go 165 ohms

Below is the specs for the stator

1980-1983 70 HP
Between blue and red stator leads 5400-6200 ohms
Between red stator lead and powerhead ground 125-175 ohms

Thanks for your help

Milton
 

Attachments

  • stator wiring.jpg
    stator wiring.jpg
    73.4 KB · Views: 79
Milton, looks like your stator has a a red, blue, and 2 yellow wires. The 2 yellow wires go to your rectifier - mine went to a voltage regulator. The red and blue wires are the ones to use to measure Ohms or resistance. When you got a reading of 16.8 Ohms, was there a smaller case 'k' to the right of the number?
 
16.8 Ohms with knob set to 2000k; that Ohms kind of mystifies me but I don't know how to interpret that since the spec is 5400-6200 Ohms; maybe some other folks can answer whether that is in spec or not; however, since you get a good spark, your stator must be working and maybe 16.8 it doesn't matter.
 
Last edited:
Back
Top