ECU - third one gone - any suggestions??? - Maxum Boat Owners Club

SWIFTSCR · 08-14-2010, 10:40 PM

over the past three years i have replaced three Engine Control Units. One on the LH ENG and two on the RH ENG. Failure occurs not when the engine is running, ie engines run great, boat sits for a few weeks then no start, ie turn over, but no alarm, no fuel pump, no ignition. Check engine with the diagnostic tester from MERCRUISER and it will not even connect with the ECU. Swap in another ECU and engine starts and runs well.
Two questions : can i have the ECU repaired? Has anyone heard of this problem.
I know ECU's never fail ..... and if they do never twice or three times ...

SWIFTSCR · 08-14-2010, 10:41 PM

by the way the boat is a 1997 Maxum 3000SCR 5.7 Mercruiser TBI, Alpha 1 genII, low time boat ....

cunuck · 08-15-2010, 01:41 PM

that is odd Have you checked for a service bulletins from merc to see if they have had problems with ecu . good luck

seapuppy · 08-15-2010, 06:49 PM

check all the grounds and connections to make sure they are clean and free of corrosion....your having a problem with either power surges or dead connections....

check the battery grounds and connections too...

SP

SWIFTSCR · 08-21-2010, 09:23 PM

thanks SP -- this is a three year ongoing snag so I've covered the basics including alternator testing and shore power surges, connections, grounds etc ... was really looking for the answers to my questions. Maxum tech support has already responded with "its not a Maxum problem need to go to Mercruiser" Thought this forum could bring out someone working in the field that has experienced this problem..
thanks anyhow ......
TS

cunuck · 08-22-2010, 12:08 AM

have you check mercruiser service bulletins I think I read something about the ecu????

LRose · 08-25-2010, 05:48 PM

Hello
Yes I have had this problem too. Im on my third Ignition Control Module or "Black Box". I have a 2006 2400 SC3 w/ a 5.7 TKS and Alpha one Gen II. The boat has stranded me 4 times w/ this problem. The first time it happened the boat had 9 Hrs on it and the Maxum replaced the ICM for free. Then it happened again a year later w/ 72 Hrs on it and they replaced the ICM again. Only this time they "Swapped Out" a few different ICMs over a couple weeks. I should have filed for a Lemon, but did not. It has failed yet again the last part of July w/ 189 Hrs on boat. Resulting in a tow 17 miles by Lady of the Lake, a Ferry on Lake Chelan. (Very embarassing getting Towed by a Ferry filled w/ people) This time I tore the Module apart to try and figure the problem out myself. What I found was a blown Diode. So this leads me to believe I have an overvoltage problem or surge. I have checked and rechecked the grounds, replaced the battery, checked continuity of wiring harness for shorts, replaced all ignition parts ie cap, rotor, plugs, coil, pick-up in cap. The last thing I have done is move the ICM away from the exhaust riser to reduce heat on module.

LRose · 08-25-2010, 05:50 PM

I have Pics of module torn apart if u are interested.

SWIFTSCR · 08-25-2010, 08:09 PM

Lrose - finally someone that doesn't think i'm crazy... not wishing bad luck on anyone else but glade to see someone else with this experience... i read your post with anticipation of a positive ending ... i have found out that Mercruiser can and will repair the ECU/ICM .. A diode repair would be an easy fix, BUT what's causing the problem .. i'm deep into troubleshooting now and finally getting help from a group of techs in our local area. I intend on getting Mercruiser involved with this problem. If you could send me a pic to tswift@mountaincable.net i would greatly appreaciat it. The minute i get any leads on the solution i'll let you know.

LRose · 08-28-2010, 03:58 AM

SWIFTSCR
OK Ill get u the pics. Im @ work now (F'in Graveyard). So maybe in the AM or later. Good Luck to you. They only problem w/ tearing apart a module is u basically have to destroy it. The electronics are encased in silicone and crushed glass. Yes crushed glass. It took me a long time to pick all the crap out. Iam trying to figure out a quick way to check an ICM in the field using a DMM (Digital Multi-Meter), because I know I will always blame the Module in the future for any other problem!!! I now have a used ICM that I carry for a spare. I got it @ Performance Marine in Everett WA. The guys there are great. They took a used ICM off a engine that is in for a rebuild for $100. The deal is that I have to give it back when they need it in the off season, and they will give me a credit for a new unit, around $600. One more thing there are two module #s 861253T1 and 861253T2 the one that ends w/ a 2 "supersedes" (Mercury's Term) the first. A module for a 5.0 will work for a 5.7 in a pinch, the spark curve is a little different and the boat will not reach max RPM's. My spare is from a 5.0. I can go on and on....

SWIFTSCR · 09-22-2010, 05:50 PM

LRose - check the back of the bell housing for a grouonding stud. Old style is grey, new style is gold. This was the problem with the LH engine on mine. Intermittent grounding to the ECM