I had posted this over in the general category, but got no response, so I'm really hoping someone will be able to point me to someone who may have an ECM....
I'm not 100% sure I do, but I am about 95% sure that I need to replace my ECM. Boat ran good all day Friday, Saturday went out, & running 4000rpms, & then dropped back to idle, checked everything...all was good. Got back up on plane, & again, back to idle (throttle was still in position). Did this a couple more times, then put it back on the trailer & brought it home. I tried to run it this evening, I get nothing...I have power everywhere, it turns over, but I don't hear the fuel pump running, & no spark. I tried to check for any trouble codes, the harness has .5 volt on the positive side of the test terminal, & I'm pretty sure it should be 12v there. So, I'm quite sure my ECM is the problem....just my luck...LOL...
So, I am hoping that someone may have a good working used one they are just dieing to get rid of...Again, 99 454 mag mpi. Or perhaps, someone knows of someone who repairs the ECM's. I plan on taking the boat down to have someone put a scan tool on it, & hopefully I missed something, but I think it's gone. Drop me a PM, or email if you or know of someone who has one they want to part with....

There is a lot of things to check on a problem like this, and a (factory) service manual and scan tool would be extremely helpful.

Have you checked the fuel pressure?

As far as the ECM being the problem, contact Bob at MEFI Burn, he may be able to test your ECM and he may even be able to repair it. I had a MEFI 1 ECM that I got on ebay that was DOA, and Bob was able to reflash it and it works great now. The guy is a true expert on this stuff.

Dave

Thanks for the input Dave,
Unfortunately, I don't have access to a scan tool until later this week. I contacted the local boat shop, & they aren't even willing to take on the troubleshooting job...oh boy...
With the test terminal showing no voltage, does that sound like it is the ECM, or is there something I could check? Do you have contact info for MEFI Burn?

Did you check the tether switch? Also the fuel pump has its own "pod" and they do sometimes go bad, but that alone will not affect spark. I'd be looking real hard at the tether switch or neutral saftey switch.

Check to see if this will work, only a few hours left
http://cgi.ebay.com/ebaymotors/Mercr...QQcmdZViewItem

Thanks for the heads up, unfortunately my connections are different than that one. I spoke with Mark at Prescision Marine, he's pretty sure he can help me out. I am going over to see him Fri morning....

Yep, checked all that....I'm not that lucky, for it to be as simple as that... thanks