Pulser coil defective

[jackmanjls]

I have 2 other posts:
http://www.yamahaoutboardparts.com/f...r-th29346.html
http://www.yamahaoutboardparts.com/f...e-th29315.html

I think I have a bad pulser coil but would like some input from the forum.

The SM says the resistance is between 459-561 ohms. I measusre 564 on coil1 (W/R to Blk) and 567 on coil2 (W/B to Blk).

Using the DVA I make the peak V measurements.

cranking (SM 3.4-3.6v) --> coil1 3.5v, coil2 4.5v

loaded (SM @ 1500rpm, 18.2v) --> coil1 20.7v, coil2 24.9v

loaded (SM @ 3500rmp, 34.3v) --> coil1 31.5v, coil2 40.6v

Based on the above data is the Pulser coil defective?

[panasonic]

What is the reason you are checking the pulser coils? The engine is not running properly I assume..so what are the symptoms?

Model and Serial number of engine would be helpful as well.

[jackmanjls]

Re: 2006, 90hp, F90TLR

Motor will start but when brought down to idle stalls.

I have 2 other posts:
http://www.yamahaoutboardparts.com/f...r-th29346.html
http://www.yamahaoutboardparts.com/f...e-th29315.html

[boscoe99]

Based on what I see I would not suspect the pulser coil as causing a problem. It is not voltage output critical. It is only being used as a reference point as to when a transistor should stop current flowing to an ignition coil.

[jackmanjls]

B99...An F90TLR does not use a CDI system. It uses an engine control unit with a transistorized ignition system. Is there a capacitor in here that I'm not aware of?

[boscoe99]

B99...An F90TLR does not use a CDI system. It uses an engine control unit with a transistorized ignition system. Is there a capacitor in here that I'm not aware of?

You got me. I have corrected my post.

[panasonic]

Re: 2006, 90hp, F90TLR

Motor will start but when brought down to idle stalls.

I have 2 other posts:
http://www.yamahaoutboardparts.com/f...r-th29346.html
http://www.yamahaoutboardparts.com/f...e-th29315.html

I did not realize it was the same engine from the other posts....I will have a look at those.

[jackmanjls]

Is there a method to use a timing light to determine if the pulser coil is firing correctly?

That would give me a better feel to determine if the pulser is defective.

[rodbolt17]

well let me think.
if the ECU on that motor detects a loss of a pulser coil it fires all 4 with one pulser signal. fixs ign timing at about 11*BTDC and idles high. top speed cannot be reached.
go hunt a different rabbit.
your not suffereing a pulser failure.

[jackmanjls]

I wanted to check the output of the pulser with the DVA. On the pulser coil there's 3 wires, the center wire is reference. I took 2 pins and slid them along side the wire into the connector. The motor ran perfectly. Went back the next day and tried the same test and it ran rough.

Thinking the issue was in the connector I made a harness, separated the connector and monitored the v with the DVA. Still ran rough.

The problem points to something in the pulser coil. Maybe something temp sensitive in the pulser coil, possible intermittent connector or something.

Absolutely all the testing I've done is well within spec. The pulser coil is the only part that I've had a ray of hope.

[ausnoelm]

Don't get tunnel visioned on a part you think "must" be faulty, it tests OK, look elsewhere, or, just to ease your mind, throw some money at a new coil, then you will have a spare for later.

[jackmanjls]

ausnoeln...funny thing you say the coil.

I sat back and regrouped. RodBolt17 says that the pulser coil is probably not bad. I went and took some new measurements of the pulser and called CDI Industries. The person I talked with verified that I probably don't have a bad pulser.

Using the DVA I tested the ignition coils according to SM. The SM calls for 290v @1500rpm. Each coil has 2 legs both are suppose to read 290v. On both coils I read ~290v on one leg and ~14v on the other. All measurements are wrt grd.

Right now it looks like the coils are bad.

I did take the new plugs out. Each plug was the same, pitch black. This tells me that possibly there's little or no spark at the plug. I will get a spark checker and verify.

[99yam40]

why would a plug that was not firing be black?
nothing there to cause carbon

[jackmanjls]

A bad choice of words by me.

I should have said low spark ouput b/c of low coil output.

[ausnoelm]

Now you're getting fixated on faulty ignition coils, didnt you say they tested in spec according to the manual? might buy a couple of them to keep in your spare parts kit.