2004 Yamaha 90 TLRB no fire on cylinder 1

[Oldsaltydog]

My son has a 2004 Yamaha 90 TLRB. Cranks and runs great until you try to get to WOT. Bogs down and falls on its face. Idles great. After doing a little checking we're finding no fire on cylinder #1. Swapped coils around and still just #1 not firing. It's getting gas to plugs, but no spark. Compression is 118 to 120 (don's remember exactly which cylinder had what, but 2 were 118 and another was 120. I've messed with a lot of motors over the years, but the last ignition problem I had with one required changing the points, so I'm not real familiar with the newer models when it comes to ignition issues.
I appreciate any ideas you guys might have.

 

[boscoe]

No points (thank God).

Electronic ignition. Capacitor Discharge Ignition system. CDI.

A coil (part of the stator) produces electricity and stores it within a capacitor that is within a CDI box. Another coil determines when the electricity is to be discharged to the ignition coil. The ignition coil increases the input voltage from the CDI box which causes a spark across the spark plug electrode and ground.

Test equipment and familiarity with the test procedures is needed. How much do you want to know?

Might be worth having a marine mechanic take a look at the motor.

 

[Oldsaltydog]

My son has a parts motor that was running great until the crankcase deteriorated due to pitting and the exhaust cover and passages beneath it deteriorated and it can't be repaired. So, we'll be swapping out powerpack, and all electronics until we get it running right. The parts motor will be used to compare wiring and will save a ton on the expensive CDI parts. At this point the "new" motor has a disabled oil pump system and a disabled overheat alarm, so we'll get that wiring correted too. You think "no points" is a good thing. I actually understand points and condensers! My first job was working at a service station in 1975. I gradually became a tune-up guy and I had a good understanding of basic points, consersers, distributors and how all that worked together. I was big into muscle cars of the late 60's, building horsepower, aftermarket camshafts, shaved heads, modified exhaust systems, jetting carbs..... All that stuff made sense to me. Electronic ignitions systems have always intimidated me. It works, or you throw parts away and replace them. I liked to see what exactly went wrong and try to figure out why. That's just me, I guess.