03 F90 won't shut off.

[Chappy13]

I've replaced the ignition switch and wiring harness and it itermittantly won't turn off using the key or the safety switch. I've asked 7 or 8 different dealers and they have no ideas. Gotta be a loose ground to the CDI or something where it wiggles. Any ideas or questions. Thanks

[boscoe99]

I would agree with you that it seems to be an intermittent ground to the CDI. Or, it could be the CDI itself.

When you say that you replaced the wire harness which one do you mean? The main engine harness or the ten pin harness?

A loose connector can be tough to find. Could be at the control box end of the ten pin harness, the engine end of the ten pin harness, or it could be at either end of the main engine harness.

If and when it happens again, and with the motor at idle RPM, disconnect the ten pin coupler at the engine. Jumper a wire from the block to the white wire pin on the main engine harness. What happens?

Do you know how to go about checking the wiring for continuity from the key switch/kill switch all the way to the end of the white wire at the CDI?

[TownsendsFJR1300]

To echo Boscoes post,

Post #22 (actually the entire thread); (another F90 as a matter of fact)

http://www.yamahaoutboardparts.com/f...h23386-p2.html

Bad connector at the ECU...Fixed!

[Chappy13]

I would agree with you that it seems to be an intermittent ground to the CDI. Or, it could be the CDI itself.

When you say that you replaced the wire harness which one do you mean? The main engine harness or the ten pin harness?

A loose connector can be tough to find. Could be at the control box end of the ten pin harness, the engine end of the ten pin harness, or it could be at either end of the main engine harness.

If and when it happens again, and with the motor at idle RPM, disconnect the ten pin coupler at the engine. Jumper a wire from the block to the white wire pin on the main engine harness. What happens?

Do you know how to go about checking the wiring for continuity from the key switch/kill switch all the way to the end of the white wire at the CDI?

No I don't. I do have a Multi meter, But not real good at using it. I did not realize there are 2 different harnesses. I did the main one that goes all over the engine. So I should find the CDI and back track from there? I don't have the boat at home, it's at the lake. Won't be able to look at it till Wed. Thursday AM.

[rodbolt17]

check continuity,while wiggleing the harness, from the engine block ground to the black wire at the switch,check the white wire the same way from the switch to the CDI.

when it wont shut off do the RPMs drop at all ??

[Chappy13]

It's already at low idle and doesnt jump from there...

[99yam40]

That does not answer his question , even if it is at low normal idle when turning off key or popping the kill switch it could drop more RPM but not die.
I am fairly sure this is what he asked.

maybe your statement it does not jump from there means it does not drop any lower.

Wiggling wires with key off and motor still running might get you to a close proximity of where the bad connection is, but using a meter will too if testing while the problem shows up or the wiggling cause a fluctuation on meter

[Chappy13]

Sorry...,Thats what I meant by "jump" It is at the lowest idle and there is no fluctuation or drop in RPMS... Sorry for the confusion......

[TownsendsFJR1300]

Sorry...,Thats what I meant by "jump" It is at the lowest idle and there is no fluctuation or drop in RPMS... Sorry for the confusion......

Did you read that link I posted earlier? It was a bad connection.

Also, agreed with 99yam40, while its not turning off(acting up), simply go thru the harness slowly (after checking the ECU connectors). If the wire is corroded internally, you'd have to push the wire together to get some contact.

[rodbolt17]

there is a reason for the questions.

I have had a few F115 motors with that same failure to shut off.

the ones with a failing ECU would drop 150-200 RPM when the key was switched off but would not shutdown or take a few minutes to shut down.

sometimes a quick knuckle rap on the ECU would shut them off.

my guess is you have an open circuit between engine ground and the white wire at the ECU.

unlike most 2 stroke EFI motors the 4 stroke has to power down.

at key off the ECU gets a shut down signal, then it has to cut off spark and fuel,reset the ISC and then shut itself down.

[greasyshaft]

I am a strong believer that any electrical problem can be diagnosed or even repaired with a small hammer

[rodbolt17]

first rule of electronics.
if you whack it and it works it was a glitch.
if you whack it and its still wont work its a casualty.

[TownsendsFJR1300]

Literally LOL!

[Chappy13]

Did you read that link I posted earlier? It was a bad connection.

Also, agreed with 99yam40, while its not turning off(acting up), simply go thru the harness slowly (after checking the ECU connectors). If the wire is corroded internally, you'd have to push the wire together to get some contact.

I did....I just can't get to the boat till tomorrow. It's 200 miles away. Thanks to you all and I will let you know when I get back if I find anything. Thnaks for your help guys...You guys know more than the Professionals...lol

[boscoe99]

Here is a diagram of the complete circuit. Hope that it helps.