1988 pro 50 cdi question

[Fatdaddy]

It seems the motor goes into limp mode... wouldn't go over 2500 rpm and it won't idle either. I did the continuity tests on the cdi, everything checked out fine except the thermo (pink wire) the resistance I get is 5.79 k ohms, the parameters in my service manual are 13 +/- 6, for a range of 7-19 K ohms. I have another used cdi that came with a bunch of electrical components I bought a while back (I needed the primary coil)... that cdi tests at 5.90 K ohms... my question is, are both cdi units no good, or is the range posted in my 1988 service manual a typo? The cdi is a pricey part, I don't want to buy one if it won't fix the problem, any input is welcomed! Thanks

[Fatdaddy]

The water pump is working great, no overheating alarm. Carbs were rebuilt over the winter and the engine ran great. This problem came up after I had run at wot for a couple hours intermittently with no problems.

[Fatdaddy]

The CDI I have is a 6H4-21, for a 3 cylinder pro 50, 1988 model year.

[99yam40]

no info on compression, spark, or timing, the simple things to test.

and no Model #

But I would be checking peak voltages into and out of the CDI

[Fatdaddy]

Thanks for the input. Checked all ignition coils, found 2 of them were bad. No continuity on the secondary side at all, checking the stator now... seems likely to me that it's gone and has taken out the cdi and a couple coils with it. Anybody have any info regarding my original question about the values in the service manual being wrong?

[Fatdaddy]

We're going to follow all the steps in the manual starting with checking the stator, I'll let you know what we find out.

[Fatdaddy]

model: Pro 50 lg #6H5L505761

[Fatdaddy]

Charge and pulser coil checked out fine, lighting coil seems a bit off, but that is only for accessories I think? Compression is good, even across all cylinders. Did a leak down test overnight, seals are fine. We found worn bushings in the con*****er, which is affecting the timing advance! I'm ordering the replacement parts today, hope to be on the water by next weekend, this one coming is a write off...oh well. I think the problem is two fold, the timing advance from the con*****er is one issue, but I've never seen 2 ignition coils go at once, neither have any of my mechanic friends... I'm going to replace the 2 coils and the con*****er bushings, then water test it. But that out of parameter reading on the thermo lead of the cdi still has me concerned... Thanks for your help 99yam40, you steered me back in the right direction LOL

[99yam40]

Did you use the proper peak voltmeter made for taking readings for this type of ignition system?

Or maybe a DVA adapter with a regular meter?

Did you test the peak voltage out of CDI to the coils?

Specs are given as a minimum


Did you check timing with a timing light to see what the idle and open throttle timing were at? And did they meet spec?

[Fatdaddy]

We used a timing light, timing was dead on. The problem was the cable con*****ing the timing advance as you roll on the throttle was not functioning properly, causing the timing to not retard as it was throttled down, which didn't let the engine idle. How do you check peak voltage out of the cdi to the coil? The test we did on the coils was for resistance, 2 of them had no continuity on the multimeter, although they still made spark outside the combustion chamber. The lighting coil had a little too much resistance, but the pulser/charger coil was perfect.

[Fatdaddy]

I can't find any values for peak voltage in my service manual... I googled how to test for it, connect the lead to each one of the ignition wires from the cdi in succession while grounding and turning the engine over. Picking up a peak voltage meter this afternoon, what should the values be coming from the cdi ignition leads?

[Fatdaddy]

I found a PDF that said a value of around 200V is acceptable for Merc or OMC, I can't find anything for Yamaha...

[99yam40]

CDI Electronics Practical Outboard Ignition Troubleshooting

Page 110 starts some Yamaha specs, but the reading is good to help understand testing

[Fatdaddy]

Thank you! I'll read through that this week.