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c40tlrx electric testing

B

BAS

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I have a c40tlrx that is running poorly. I have rebuilt the carbs and set needles to factory spec at 1.5 turns, new fuel pump, new fuel lines with new clamps and connector and cleaned the fuel tank and tested for air leaks and vent clearance. Seems to be getting fuel. It is bogging down like it needs fuel at all throttle ranges but at <1000rpm it backfires and wants to conk out at <800 rpm. Another tell tale is the sooty oily residue it is spewing. Compression is 124/123/124. Using a factory service manual and peak voltage Multi Meter (DVA) I went through the trouble shoot sequence listed.
1-Checked SP gap at .10, good. Tested spark at 9mm good and bright
*2-CDI Output- cranking spec is 125v I was showing 9.5-11.5v, I tried switching between ac and dc and got the same and got sevral readings ranging from 200v-400v on AC
3-Measured coil output @ cranking and was 145v, good
*4-Measure Pulser Coil- Get different readings on each pin, 7.9v-9.4v-15.1v (spec is 3.0v @ cranking)

* This is my issue: the CDI output and Pulser coils utilize a three pin harness, which I dont have so I tested the pins individually. Can I assume that these readings are correct or incorrect. Shade Tree "Algebra Kicked My Ass" Logic tells me that each pin is responsible for firing a specified (same or close to same for each) charge thru its circuit to fire the coil that in turn fires a charge to the plug and that reading should be obtainable from each pin, however, this being the world of outboards is similar to the platypus in which all scientific rules are tossed! lol
Question: Can I use individual pins to test the elements as per specification or do I have to purchase a test harness adding $50 to the cost of what, based on my backyard analysis and the manual say, to be a screwed up CDI? :( ($400-$500! ouch)
Followup if yes I need a harness, Can I make a harness that essentially allows me to read the three pins on one red MM test lead and then ground the black MM lead to the engine block? Im assuming if I do that I could possibly backfeed, for lack of a better term, each of the circuits and then I will definitely need a new CDI which while I would know that the CDI is f'd I would still have the original issue lol
On one other note I did run the engine without the R/R plugged in and it still ran like crap! I was hoping that was the issue... no dice
 
Bogging is usually fuel related. As in not enough fuel for the amount of air. Backfiring is a symptom of a lean mixture. As in not enough gasoline for the amount of air.

I would have someone start misting some gasoline into the air intake system at about the time the motor starts to bog down. See if the motor picks up and runs with some misted gasoline being provided.

Carburetors are known to be problematic. Yamaha electrics are known to be very reliable. There are orifices (holes) and passageways within carburetors that are damn near impossible to get clean.
 
*Update*
Went and got a timing light and shot all cylinders, observed flashes.
#1- Good steady light with a small hiccup that was not very noticable
#2- 10-15 shot pattern then a noticeable break in flashes
#3- 10-15 shot pattern then a noticeable break in flashes
Put light on flywheel. Set motor at full retard:
#1- Mostly at 7d ATDC with an intermittent bounce every 5-10 sec that moved to 8-10d ATDC returning to 7d ATDC
#2- Hahahaha... bouncing between 7d ATDC on #2cyl and 7d ATDC on #3 cyl with some flat spots that would be indicative of a dropped cyl
#3- Bouncing between ATDC on #2 and #3 cyl's
This leads me to believe the CDI is sending poor information. I forgot to mention in the original post that I also bench tested the 3 coils and they all were in spec.
Boscoe, I did a pretty good cleaning on the carbs twice. Full rebuilds both times with overnight soaking in Napa carb cleaner and comp air blow out. I'm not sure if a fuel system issue would lead to cylinders dropping, do you think this is the case?
Anyone, I think it's the CDI, all other ign components are in spec per Yamaha's factory service manual for this engine. Id love to save a few hundred bucks, but it's duck season here and for the first time in decades it's cold, really cold up north pushing the birds past DU's short stop points in IO, MO and AR! (Relax that's a joke) I gotta get this bad boy back on the water!
 
OOPS! I forgot to give the specs @ 3000 rpm
#1-18d btdc with a hiccup
#2- 15-22d btdc on #2cyl and a fire on #3 cyl but to fast for me to read, just enough time to see it flash on #3 mark
#3- Pretty much same as #2 cyl
 
It's been a while and I thought I would give an update on what the issue was...
First let me say that due to the age of the engine and it's generally good mechanical condition I decided to replace the ignition system including CDI. At close to 20 years I figured stuff was due and with each repair would come another spent part. That said after each component I replaced I would run and test, sadly everything I replaced had no effect on the performance issue! I replaced in this order:
pulser coil
charge coil
cdi
each ignition coil (3)
plugs
After all that I was thinking it was possible that a fouled carburation system could indeed cause timing to be thrown off.
I spoke to a friend who is a mechanic who said to check the rectifier. "Wut, it is delivering 13.5v at 1000rpm and goes up to 15v as throttle increases". He said that the rectifier does some other stuff that will throw the ignition off yet still perform as it should charging the batteries. Part was cheap enough, so what the heck, I just spent close to $1000 on the rest of the ignition system what's another $65? Replace rectifier and BOOM! engine runs as it should, all readings in spec and with a few idle adjustments, everything is gtg. Now off to catch some Sacalait!
 
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