2003 Z150TRLB ECM Main Relay Issue

[Mr. Nice Guy]

I'm hoping someone will have some insight to help me. I purchased this low-hour Z150TRLB (150 HDPI) motor that would start only if starting fluid was sprayed into the intake. Here's what I've learned:

1. The ECM relay on the fuse block (shown as #12 on the wiring diagram) had been replaced with an automotive fuse (they subsequently cut the plastic to make it fit) - and, the relay housing was cracked.
2. When the relay was squeezed together (creating a contact) - the motor would start and run perfectly. When the relay was released, the motor stops and won't fire.
3. I replaced the relay (and the entire fuse block)
4. Motor will turn over, but relay won't engage (I should expect a click at key switch, right?)
5. Connected YDS - all systems come back fine. Fuel pump/oil pump activate with no issues. (interesting side-note, the ECM reports only 25 hours on the motor... I'm guessing it was replaced? Although the motor is spotless and looks practically factory-fresh)
6. Tested kill switch lanyard - alarm sounds, works as expected
7. Checked oil float switch, meets specs
8. Checked all fuses on fuse block, meet specs
9. Checked neutral switch

Anyone have some ideas? I'm a bit confounded at this point. Clearly there's some sub-system that's not sending an "OK" for that relay to close and allow the engine to fire.

Thanks in advance for your help!

[boscoe99]

To what wiring diagram are you referring? What page number? We all need to be on the same page.

If the motor started using starter fluid, what was the purpose of testing the kill switch circuit?

If the motor started using starter fluid, what was the purpose of testing the oil float switch?

If the motor started using starter fluid, what was the purpose of testing the neutral switch?

[99yam40]

I am thinking he was just making sure those did what they should be doing

"If the ECM relay on the fuse block had been replaced with an automotive fuse
and when the relay was squeezed together the motor would start and run perfectly
When the relay was released, the motor stops and won't fire."

if the relay was replaced with a fuse, how could you squeeze the relay?


" I replaced the relay (and the entire fuse block)
Motor will turn over, but relay won't engage "

maybe they put the fuse in place of the relay because the relay was not picking up for them also

[Mr. Nice Guy]

Sorry, I'm using the Yamaha Service Manual (part no. 68F-28197-1F-11)
The page is the Wiring Diagram located at the back of the service manual.
Testing the switches was simply being as thorough as possible... I actually did not experience the motor start with starting fluid - this was the claim made by the person I purchased from - sorry for not explaining that..After reading many posts about these kinds of issues - it seems that those tend to be culprits of non-starts - so, I was making sure to eliminate them before asking here

[Mr. Nice Guy]

The old automotive relay (sorry, not a fuse) had the broken housing and allowed the contact to be manually closed (essentially jumping the circuit) and the motor would run. But, the motor would not run without that relay being manually squeezed...
Whatever sends the "ok" signal to that relay to close isn't happening - but, I can't figure out what it is.

[99yam40]

OK,
do you have some idea what that relay #12 is called?
surely there is a legend somewhere saying what #12 is

[boscoe99]

The old automotive relay (sorry, not a fuse) had the broken housing and allowed the contact to be manually closed (essentially jumping the circuit) and the motor would run. But, the motor would not run without that relay being manually squeezed...
Whatever sends the "ok" signal to that relay to close isn't happening - but, I can't figure out what it is.

The relay has battery power to the control circuit side of the relay. Through two fuses. Verify that battery power is provided to the relay control circuit. I doubt that it the issue however.

[rejesterd]

Test the ECM itself. The manual should tell you how to do that. It might be fried.

[boscoe99]

The main relay control circuit is grounded by the ECM to close the relay contact. The ECM should do this when the ECM receives battery power via the key switch being turned to the ON position. The blue/yellow wire from the ECM to the relay control circuit is the ground lead for the relay control circuit.

Does the control circuit for the main relay have a ground applied to it when the key is turned on?

[boscoe99]

OK,
do you have some idea what that relay #12 is called?
surely there is a legend somewhere saying what #12 is

Come on man. If we had all of the needed information this would not nearly be as much fun.

[boscoe99]

Test the ECM itself. The manual should tell you how to do that. It might be fried.

It should.

It does not.

[rejesterd]

If the service manual doesn't give a spec for ECM and pulser coil output peak voltage, that sucks. But that's the test as far as I know. If output peak voltage of the ECM is too low and the pulser coil output peak voltage is too high, that indicates the ECM is bad.

If the ECM reads 25 hours on a 2003 engine, it is either damaged or it was replaced at some point (and the new one is possibly damaged for the same original reason it was replaced).

[Mr. Nice Guy]

Sorry - I thought I had called it correctly as "The ECM relay on the fuse block (shown as #12 on the wiring diagram) "... my apologies for not being more clear.
Would the motor run if the ECM was fried (as, it will run perfectly if that relay is jumpered)
Would the YDS be able to diagnose if the ECM was bad?

Boscoe99 - thank you, I will check that circuit specifically.

I appreciate all of your input - thank you!

[rejesterd]

Does it run perfectly under load? I wasn't sure based on the description. An engine with a damaged ECM can still run (depending on the damage), but I don't think you'd be cruising perfectly at high speeds.

It just seems odd that it's reading 25 hours for an engine that old. If it does run fine at higher speeds, then I would test the relay itself after removing it. Then dig into the wiring/fuses.

YDS can't diagnose the ECM itself though.

[99yam40]

If the service manual doesn't give a spec for ECM and pulser coil output peak voltage, that sucks. But that's the test as far as I know. If output peak voltage of the ECM is too low and the pulser coil output peak voltage is too high, that indicates the ECM is bad.

If the ECM reads 25 hours on a 2003 engine, it is either damaged or it was replaced at some point (and the new one is possibly damaged for the same original reason it was replaced).

Maybe you need to tell what this ECM peak voltage is, what is suppose to do, and where it is to be measured