Logo
FULL SITE MENU

BF50 Carb CDI difference (2001 vs 2006)

K

keada714

New member
Hey all,

I'm wondering what the difference between the BF50 CDI unit from 2001 with part number 30580-ZV5-003 vs one from 2006 with part number 30400-ZW4-H03. I'm having some intermittent spark issue on cylinder 2 that is not allowing to motor to run correctly. It looks like the pre 2004 the CDI came with wires coming directly out of it while the 2004 and later units came with wiring harness. I am able to get a brand new 2006 CDI unit with wiring harness but I want to make sure its interchangeable before doing so.

As far as the intermittent spark issue. When the motor is running poorly and I pull the wire and place it near a bolt I do not see any spark and of course it doesn't make a difference in how it run. However, when its running correctly and I pull the wire, it will run poorly and I see spark when grounded. I have checked resistances for the following: charging coil, excitor, 3x pulser coils and ignition coils. All is in spec per service manual with the exception of the charging coil measuring .9 - 1.1 ohms and no short to ground. I'm getting a good charge of over 13v to the battery and I'm under the impression that the charging coil has no affect on the ignition system. I have also replaced the pusler and ignition coils and still getting a drop in cylinder 2. With this diagnosis I have narrowed it down to a bad CDI.
 

Attachments

  • CDI.jpg
    CDI.jpg
    93.2 KB · Views: 91
Hi,

I can't answer your question but suspect that, with a WHOLE BUNCH of careful study of BOTH wiring diagrams for both models, making the newer CDI work  might work. But it sounds like you probably know WAAAY more than me about the BF50.

I really only chimed in to make a suggestion about what I see in the parts diagram about the 2001 model.

Item 11 in the link below is the "pigtail" harness for the ground side of all three ignition coils.


Before condemning the CDI, I would thoroughly inspect that harness....even to the point of load testing each wire. Because, load testing is really the only reliable way to pass/fail for an intermittent condition like this.

Actually, I would want to load test the wires for the opposite coil terminals as well but having them permanently attached to the control unit makes that impossible it seems.

While you may be correct that the #2 coil driver is failing, my experience with solid state electronics is that, for the most part, failure more often looks like a switch turning off....permanently.

I would be very reluctant to focus on the CDI until I found out as much as possible about everything else in the circuit.

Just my opinion though.

BTW, I agree that the charging system has no bearing on the ignition system.

Wishing you good luck with this.
 
Thanks for chiming in. You seem to be the local guru on these Honda motors!

I have inspected that ground harness and physically looks good and there is continuity between the ground point and 3 individual wires going to the coil. I have also "played" around with that harness trying to induce failure with no commonality. With that said I'll load test to ensure it is not giving me intermittent open circuit. Better yet I'll make me own ground wire for the coil #2 using the same ground points as the other coils and CDI.
 
I'm certainly no guru....I think it's the other "G" word that might make it seem that way...ie: geek.

I've never actually touched a BF50. But there are others here that probably do fit into the guru category.

Like I said before, you know more than I do about your outboard. And, you already seem to be way ahead of me with the troubleshooting as well.

Would you happen to have an oscilloscope? I was thinking this might be a good candidate for using one because you could compare the waveforms of the bad cylinder coil driver to the two good cylinders.

That could at least let you verify that the issue IS in the primary circuit and not in the secondary.
While it's best to probe it while it's acting up, you might still catch a slight difference between the good and bad cylinders even when the engine is running ok.

That might sound a bit much to most folks but it's just that Honda CDI units are so reliable I always suspect them last. The cost and, in this case, the complete hassle of finding a replacement has me thinking "proceed with caution".

They DO fail sometimes though so...who knows?

Please update with what you find and....
Good luck!
 
I could not get the later CDI unit to work correctly with my motor even with the harness. Purchased a second hand CDI unit from eBay so I will update in a couple weeks. Unfortunately I do not have an oscilloscope. Noticed when the motor is cold it will run correctly but after warming up is when I start to get the intermittent issues.
 
Looking forward to seeing how it shakes out.
Meanwhile, sitting here holding down the cheering section bleachers with fingers crossed.
 
the second hand CDI got the boat running much better with no more drop off of cylinders. I do now have an idle that is slow to drop and a very low speed shutter here and there.

Top carb has a broken air fuel screw. Middle carb is about 2.5 turns out and the bottom carb is about 3.5 turns out. From what I read these carb should be about 2 to 2 1/4 turn out. When I went through these carbs, the air fuel screws was not removed and cleaned due to lack of knowledge on removing the caps. Is it worth breaking down the carbs and removing and cleaning the orifices of the air fuel screw? I pulled screws from 2 and 3 and o-ring and screw looks good without buildup.

Plan is to extract the top air fuel screw and adjust them all to get the highest idle. Then sync them via manometer. Hopefully this is enough to smoothen the rest out. Really don’t want pull the carbs out again..
 
Back
Top