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Honda B 40A not turning over/computer board overheating?

G

GPSAR2000

New member
Hey everyone, first time poster in need of some help.

We have a Honda BF40A Model BAYS3700315 that is giving us some issues.

The engine will crank and not turn over and the computer board gets very hot when doing so. Replaced the computer part once last year and we are still having the same issue.

I apologize for the vagueness of the issue description, I dont know my way around outboards thats for sure.

I run with an all volunteer search and rescue team in the Philly area. We dont have a ton of funds to send it out so we are looking to try and handle it ourselves, if possible.

Thanks in advance!
 
Hi GPSAR,

First off, goodonya to you and your volunteer compatriots for the generous service you all provide.

Need to clarify some terms...
When you say "computer part" you are referring to the CDI unit...
correct? See item 1 in the link below

Honda Outboard 40HP OEM Parts Diagram for C.D.I. Unit | Boats.net

Buy OEM Parts for Honda Outboard 40HP C.D.I. Unit Diagram
www.boats.net www.boats.net

If that is what you replaced, I'm curious as to where you got one since it appears to be no longer sold by Honda.

Anyway....
Any engine that won't start or "fire and run" is usually missing one or more "component" of the things needed for ignition. Those are...in no particular order....
Air
Fuel (good fuel)
Spark
Compression
Timing
But, for about 99.999% of the cases it's going to be either no fuel or no spark. So that simplifies things (most of the time)

So, your task is to figure out which of those two things is missing and then proceed.

An inexpensive spark tester, that you put in place of a spark plug, from Harbor Freight Tools can be a real help to check for the spark.

If it has spark while cranking, then it is very likely that it's not firing due to lack of fuel.

QUESTION: Did you save the original CDI unit? Hopefully you did.

If so, I urge you to put it back and here's why:
You say the unit is getting hot. It was before and it still is. If you were able to obtain the correct replacement CDI, I would hate to see you damage that one before identifying what is causing the heat and possibly taking out the component. That is, if it hasn't been damaged already.

I will leave it there. You can choose to test for spark or try artificially adding fuel...carb spray or propane.....I do NOT recommend ether (starting fluid) as it can easily damage the engine.

But, in this case, checking for spark, with a spark tester, is going to be the easiest.
 
Hello!

Thank you for that response. I will check to see what the computer part is/was. Our prior boat guy on the team took care of it but he has since retired so I will attempt to piece together some more information for you. I will see the boat/engine on sunday and see if i can get anywhere with your suggestions.

You're right, Honda doesn't sell that part so I'm not sure where the prior guy sourced it from, but excellent point about switching it back.

I'll update if/when I can!

Thanks again!
 
OK, so the old CDI was fried and trashed.
Now the tilt on the side of the engine has power when connected to the battery, but there is nothing happening when you turn the key. no noise, no nothing. stumped. im assuming electrical, but i have no idea. Gonna get one of those spark plug testers this weekend and see if that works.
 
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