1988 Yamaha 150 CDI Box

[Z-man228]

It has been the summer of boat repairs for me. First a overheat issue that I cured with the help of you all and now it appears I dropped a CDI box opening week of lobster season. Now, I am not complaining since the motors are 26 years old but those little boxes are expensive. I swapped the CDI from my starboard motor to the port and it ran perfectly so I have already ordered a new one from this site and am waiting til 9/2 to get here as it is backordered until then. However, my question is this
1) Is there a way to rebuild a CDI so I could have a backup
2) Is there a way to check them without having the yamaha meter the manual suggest.

I am going to replace this one either way since it cured the no spark issue on the port motor but would like to have a backup in case it ever happens again. It totally ruined my vacation in the Keys as the boat ran fine all week and then died at noon on opening day. Without the second motor the boat would get on plane and going under 7 mile bridge in a ripping current was no fun either on one motor

[99yam40]

Print Out This Guide, The Use of Electronic Test Equipment for Outboard Motors.

DVA adapter and regular meter will take peak readings.
Have not seem anyplace that rebuilds the CDI but there may be some one out there that does.
Maybe these guys CDI electronics, a division of Rapair, Inc.

[Z-man228]

Christmas came early and my CDI got here yesterday. Thanks Boats.net!!!! Already installed CDI and both motors idling along at 700-800 rpm in nuetral. Taking to the lake this weekend and then start planning for next grouper trip

[Z-man228]

Having an issue with CDI. Here is a brief history:
2007 Lost CDI on Port motor while in the Keys.
Mechanic Swapped CDI from Starboard to port motor and it worked. Sold me a USED CDI and Installed on starboard Motor. No Issue ran fine til August '14
Dropped CDI on Port motor (used to be Starboard CDI box). When I took cover off Starboard side CDI to Swap to port motor I found 2 of the wires where held in place with stripped screw and a grey silicone. I never knew it was like this as mechanic installed 7 years ago. Pulled the starboard CDI and Installed on Port motor and fired it up. No Problem idled great. Ordered new CDI and Installed on Starboard motor since "old" one worked on port motor.
I took it to the lake and at first everything was fine, then motor started cutting in and out (like it was dropping a cylinder) then went back to the way it was running before I swapped CDI (3 cylinders). pulled CDI cover and wire on bottom left side of cdi was loose ( due to stripped hole in CDI) pushed wire in tight and it went back to idling fine.
there is one other spot where the hole for the screw is stripped and I can only assume that is what is causing the dropped cylinder. I need two things from an expert on the forum:

I can't afford to buy another new CDI so can I either get a bigger screw to hold wires in place? or silicone it back in like the other mechanic did?

Also, is there someplace I can look to see exactly what wire controls what coming off the CDI so I know if the second loose wire controls a particular cylinder or not?

[Z-man228]

to clarify further it is a 1988 L150 etxg. the brown wire on the bottom left is loose due to the stripped screw and the black/white wire 4th from top on left side of CDI was the other one but I may have just fixed it.

[boscoe99]

I would try and find a slightly over sized screw.

A lot of backyardigans like to tighten fasteners to the point that they just start to get loose again.

When you're down to nothing you go nothing to lose.

[rodbolt17]

about three options.
1 buy a new CDI.
2 try to rethread it slighty oversized.
3 toss the engine in the creek.


self tapping screws may work.

[Z-man228]

motor runs to good to toss it in the creek just yet. I assume the screws are metric so I may try a SAE and see if it will thread in. Also figured out Black and white wire comes of coils. the one that was loose was loose because I did it. I was being so careful not to overtighten when it got a little tight I quit turning the screw, went and snugged it down and motor purred along at 800 rpm idle. Will stick new screw in and see what happened. What does brown wire on Bottom of CDI control?

[rodbolt17]

actually the B/W wires go TO the coil.
they are the CDI OUTOUT wires TO the coil primary windings.

[Z-man228]

does the brown one control one whole bank of cylinders. This is the stripped hole and caused the motor to run like crap when wire got loose. when I wiggled/tightened it up motor went back to running normal

[rodbolt17]

yes, its part of the cdi charging circuit.

[Z-man228]

thanks rodbolt Thats what i needed to know.

[Z-man228]

Ran the boat and everything Is fine now. In my effort to make sure I did not overtighten and strip any screws I did not tighten 2 of the wires for the coils enough. Went back and tightened everything up and it runs now. Thanks Rodbolt and Boscoe