ECM no good

puremaple · 01-23-2026, 01:52 PM

I was recently told that the ECM on my 2000 Mercruiser 7.4 mpi is no good. And to make matters worse it is no longer supported by Mercruiser... Has anyone had any luck with a remanufactured ECM?

DesertDweller · 01-23-2026, 04:15 PM

https://obd2allinone.com/ecmrepair.asp

Name came from a boating forum I am on. Sounds like they can either repair your ECM (if possible) or sell you a remanufactured unit. Diagnostic fee is $80. Probably worth a shot.

BroadHopper · 01-24-2026, 08:06 AM

Glad I have an engine with no ECM, just CDI. Extremely reliable.

TomC · 01-24-2026, 08:23 AM

A boat salvage place can probably hook you up. There was one in Meredith (M & M), but it doesn't look like they are there anymore (?). There are others in NH - here's one: www.kmsboatsalvage.com

Slickcraft · 01-24-2026, 08:55 AM

In the past, Fay's has had a collection of salvaged parts.

Alan

Lakes Region Guy · 01-24-2026, 01:30 PM

What do ECM and CDI stand for?

TomC · 01-24-2026, 02:55 PM

Engine Control Module & Capacitive Discharge Ignition

Bootkie2 · 01-27-2026, 03:58 PM

My first question would be how do you know for certain that it's your ECM that has gone sour?

DesertDweller · 01-27-2026, 07:23 PM

Quote:

Originally Posted by Bootkie2

My first question would be how do you know for certain that it's your ECM that has gone sour?

That would be my question as well. Getting it diagnosed for $80 might end up pointing you in a different direction.

puremaple · 02-10-2026, 11:01 AM

I dont have the write up in front of me but, I brought it in for not starting after stalling while out for a run... I thought it was old fuel so I did the fresh gas in a portable can with the primer ball to a new filter and was able to get it running for 15 seconds, then nothing after that.
They found good compression, and dry cylinders so they removed fuel rack and were able to determine that the injectors worked with ecm bypassed and concluding that the ecm was not giving the signal to the injectors.

Went to the boat show, so I will be looking forward to sending this out to be tested for 80 bucks.

ApS · 02-12-2026, 09:14 AM

ECM "tuners" are everywhere for automotive ECMs--especially in racing applications.

If diagnostics indicate a faulty ECM, maybe give them a try:

ECU & Dyno Tuning Workshops in New Hampshire (NH) | Dynoseek USA https://share.google/N6L1XlFZcxsXUlinV

Bootkie2 · 02-13-2026, 09:54 AM

Quote:

Originally Posted by puremaple

I dont have the write up in front of me but, I brought it in for not starting after stalling while out for a run... I thought it was old fuel so I did the fresh gas in a portable can with the primer ball to a new filter and was able to get it running for 15 seconds, then nothing after that.
They found good compression, and dry cylinders so they removed fuel rack and were able to determine that the injectors worked with ecm bypassed and concluding that the ecm was not giving the signal to the injectors.

Went to the boat show, so I will be looking forward to sending this out to be tested for 80 bucks.

ECU failure isn’t super common, and from how you described it, it sounds like the diagnosis may have taken a bit of a roundabout path with some mixed signals along the way. The easiest test probably would’ve been to bolt your ECU onto a known-good 7.4 and see if the stalling followed it. That would’ve confirmed things with a high level of certainty pretty quickly instead of sending you down the rabbit hole of ECU tuning and repair. Sounds like you are already down that path though so keep us posted and let us know how it works out!

puremaple · 04-23-2026, 10:55 AM

Update:
I found a guy in Virginia Maic Salazar diagnostics who confirmed the fuel injectors not getting the correct signal and repaired the ECM. Started right up!

01-23-2026, 01:52 PM	#1
puremaple Junior Member Join Date: Sep 2021 Posts: 12 Thanks: 30 Thanked 1 Time in 1 Post	ECM no good I was recently told that the ECM on my 2000 Mercruiser 7.4 mpi is no good. And to make matters worse it is no longer supported by Mercruiser... Has anyone had any luck with a remanufactured ECM?

01-24-2026, 08:06 AM	#3
BroadHopper Senior Member Join Date: Oct 2004 Location: Laconia NH Posts: 5,667 Thanks: 3,280 Thanked 1,132 Times in 814 Posts	Glad I have an engine with no ECM, just CDI. Extremely reliable. __________________ Someday may never be an actual day.

02-10-2026, 11:01 AM	#10
puremaple Junior Member Join Date: Sep 2021 Posts: 12 Thanks: 30 Thanked 1 Time in 1 Post	Ecm I dont have the write up in front of me but, I brought it in for not starting after stalling while out for a run... I thought it was old fuel so I did the fresh gas in a portable can with the primer ball to a new filter and was able to get it running for 15 seconds, then nothing after that. They found good compression, and dry cylinders so they removed fuel rack and were able to determine that the injectors worked with ecm bypassed and concluding that the ecm was not giving the signal to the injectors. Went to the boat show, so I will be looking forward to sending this out to be tested for 80 bucks.

02-12-2026, 09:14 AM	#11
ApS Senior Member Join Date: Jan 2005 Location: Florida (Sebring & Keys), Wolfeboro Posts: 6,028 Thanks: 2,284 Thanked 789 Times in 564 Posts	"Tuners"... ECM "tuners" are everywhere for automotive ECMs--especially in racing applications. If diagnostics indicate a faulty ECM, maybe give them a try: ECU & Dyno Tuning Workshops in New Hampshire (NH) \| Dynoseek USA https://share.google/N6L1XlFZcxsXUlinV

01-23-2026, 04:15 PM	#2
DesertDweller Senior Member Join Date: Aug 2011 Location: Las Vegas, NV and Moultonborough, NH Posts: 403 Thanks: 27 Thanked 96 Times in 80 Posts	https://obd2allinone.com/ecmrepair.asp Name came from a boating forum I am on. Sounds like they can either repair your ECM (if possible) or sell you a remanufactured unit. Diagnostic fee is $80. Probably worth a shot.

The Following User Says Thank You to DesertDweller For This Useful Post:
puremaple (02-10-2026)

01-24-2026, 08:23 AM	#4
TomC Senior Member Join Date: Apr 2004 Location: Lakes Region Posts: 816 Thanks: 42 Thanked 185 Times in 116 Posts	A boat salvage place can probably hook you up. There was one in Meredith (M & M), but it doesn't look like they are there anymore (?). There are others in NH - here's one: www.kmsboatsalvage.com

The Following User Says Thank You to TomC For This Useful Post:
puremaple (02-10-2026)

01-24-2026, 08:55 AM	#5
Slickcraft Senior Member Join Date: Mar 2008 Location: Welch Island and The Taylor Community Posts: 3,384 Thanks: 1,260 Thanked 2,148 Times in 983 Posts	In the past, Fay's has had a collection of salvaged parts. Alan

The Following 2 Users Say Thank You to Slickcraft For This Useful Post:
LIforrelaxin (01-27-2026), puremaple (02-10-2026)

01-24-2026, 01:30 PM	#6
Lakes Region Guy Member Join Date: Jan 2018 Posts: 27 Thanks: 1 Thanked 8 Times in 5 Posts	What do ECM and CDI stand for?

01-24-2026, 02:55 PM	#7
TomC Senior Member Join Date: Apr 2004 Location: Lakes Region Posts: 816 Thanks: 42 Thanked 185 Times in 116 Posts	Engine Control Module & Capacitive Discharge Ignition

01-27-2026, 03:58 PM	#8
Bootkie2 Member Join Date: Dec 2016 Posts: 36 Thanks: 1 Thanked 9 Times in 7 Posts	My first question would be how do you know for certain that it's your ECM that has gone sour?

The Following User Says Thank You to ApS For This Useful Post:
puremaple (02-26-2026)

The Following User Says Thank You to Bootkie2 For This Useful Post:
puremaple (02-26-2026)

04-23-2026, 10:55 AM	#13
puremaple Junior Member Join Date: Sep 2021 Posts: 12 Thanks: 30 Thanked 1 Time in 1 Post	Update: I found a guy in Virginia Maic Salazar diagnostics who confirmed the fuel injectors not getting the correct signal and repaired the ECM. Started right up!