2001 225 Optimax bad ecm

[StealinThunder]

Serial # 0T279963

Back story:
A couple weeks ago we were coming back in from checking our crab pots, we were getting 4 beeps but only at idle. I figured it was a water pressure code, as once we got on plane it was fine. It never read over 125* on the gauge at idle or on plane.

In the no wake zone it cleanly shut off, just like you turned the key off. It was low on gas so I thought maybe we ran out, get towed to the fuel dock and afterwards it wont start...no spark and has fuel pressure (I just pushed the shrader valve, no gauge).

When you turned the key on there was a good 15-20 second delay before the single warning chime and the fuel pumps would come on and prime...they would run 2-3 seconds and stop and then every 10 seconds or so repeat the process over and over again.

Ive been checking everything on the motor I can touch, checked/cleaned the grounds, unplugged every sensor to check inside including the 8 pin harness, ohm tested every sensor and the only thing I found was a bad coil. Which made sense because I remember on the way back it just didnt feel like the power was normal. I borrowed a Rhinda scanner with a new update and it wouldnt connect, it gave me an error like the key wasnt on (but obviously it was).

I sent the ecm to Simon Performance and they repaired it, invoice says "major component replaced". The lady that called when it was ready spoke to my dad and said it had nothing to do with the coil driver and that what they replaced "was a component that burns out like a light bulb".

This is scary to me, as I dont want to put this thing back on and risk frying it again without finding the problem first.

I did install the ecm last night just to see if the scanner would connect and it did. It had 3 faults that were nothing major, 75 fuel level circuit 1 high, 104 sea temp circuit high, 131 trim sensor circuit low.

Anything else you guys can think of to check?

Is there any tests I can do to the alternator without taking it off, I read that a problem inside could kill the ecm. It charges fine per the gauge.

Thanks for any help

[Bob G.]

I would have taken the boat/motor to a Mercury dealer before sending the ECM to a third party to be repaired or reflashed. Have a dealer get the full printouts before performing anymore troubleshooting.

[StealinThunder]

I tried to scan it before I sent it anywhere, paragraph 4 last sentence.

[EuropeanAM]

Very unlikely that the alternator is the culprit- if you want, you can check AC VOLTAGE across the two battery terminals while the engine is running (at idle). Set meter to AC volts, and DISABLE any auto-ranging feature.

You should have no more than .25 VAC between the two terminals (readings higher indicate a diode problem in the alternator).

If you replaced the known bad coil, verified a good, properly rated battery, verified CLEAN connections stacked ENGINE CABLE FIRST, remaining Largest to Smallest, and finished off with a Stainless LOCKNUT, there is not a whole lot for you to do beyond this.

[StealinThunder]

Very unlikely that the alternator is the culprit- if you want, you can check AC VOLTAGE across the two battery terminals while the engine is running (at idle). Set meter to AC volts, and DISABLE any auto-ranging feature.

You should have no more than .25 VAC between the two terminals (readings higher indicate a diode problem in the alternator).

If you replaced the known bad coil, verified a good, properly rated battery, verified CLEAN connections stacked ENGINE CABLE FIRST, remaining Largest to Smallest, and finished off with a Stainless LOCKNUT, there is not a whole lot for you to do beyond this.

Gotcha, I will run that test when I receive the coil later this week. I felt like I was pretty much out of options but just wanted to make sure there wasnt something I was missing.

Thank you sir for the reply!