90 tlra CDI peak voltage measurement.

[holmen78]

Service manual says 130V minimum on cyl 1 and 3 @cranking? And cyl 2 should be zero, or what does the dash mean? I’m getting 110V on cyl2, over 130 on the other two. Still waiting on 2 test harnesses so I can test charge and pulser coils connected. Crank position sensor reads below 5V @cranking.

[holmen78]

Ok. Read a 2 year old CDI thread on this site and now I think I know why the cyl2 has a dash in the service manual. It’s because the crank position sensor gives signal to the CDI for cylinder number 2. Pulser coil gives the signal for cylinder 1 and 3.

I also did a mistake while measuring peak voltages @CDI output, had the wrong scale on my analog DVA meter. CDI output on all 3 cylinders are 10 V while cranking. Minimum should be 130V at cranking. It’s a miracle the engine fires up. @1500 rpm the CDI output is 180V (150V minimum) and @3500 rpm CDI output is125V (130V is minimum)

Measured all CDI inputs (DVA) and resistances (pulsercoil, charging coil, crank position sensor), and all are within specs or over minimum while cranking.

Im still waiting on a couple of test harnesses to test everything connected.

Looks like my CDI is fried

[99yam40]

I am sure you are still reading the outputs wrong,
The plugs would never spark with only 10 volts going to the ignition coils

you may want to say what meter, what scale, and what leads you are hooking up to.
Some thing is not right

[holmen78]

Yeah, you are right. I was stupid enough to not turn the ignition key to on position. (I cranked the engine by touching brown wire to ignition relay +. That’s why I got low readings on the CDI. Have to wait for the test wires so I can test a running motor in the water.

Lost cylinder 2 on my first trip. Went back to harbor. The next day motor fired up on all 3, was going for another test trip and 1 cylinder lost again. Took it out from the water and started to measure but everything works here at the homeyard. Need to get it bogging at water with measure equipment attached to pin it down I think.

[99yam40]

a lot of people will back probe the connectors with a small paper clip or straight pin, being careful not to damage the wire insulation or the connectors.
then hook the meter leads up to those to get a running reading.

but then you have already ordered the test harnesses.


have you decided which cylinder is cutting out?

#3 can stop firing even if spark is still getting there if the fuel pump leaks into the crankcase.
have you checked the resistance of plug wires and caps

[holmen78]

I think it was cylinder 2 that cut out. It was the only one with a wet plug. I was dumb enough not to pull caps while it was missing a cylinder.

Fuel pump is brand new so I don’t want to think it’s that. I have measured every resistance in the service manual and all are good. Ignition coils primary/secondary measured good. The caps had 5M ohm and they should have a built in resistor. Going out on the water for more testing today or tomorrow.

Im a little suspicious at the CPS if that is telling the CDI when to fire cylinder #2? It had a low output a couple of days ago but slightly over minimum (5.5V) yesterday when tested.