225 Pro Max Quits

[GSM]

Will be running fine then just shuts down. Doesn’t hit at all when trying to restart
Both times it has happened will restart about 1 hour later. Made it back to ramp last time then died as soon as I got it on the trailer

Any ideas ?

[mactlman]

Did you post in the Mercury two-stroke area below? you’ll need your serial number to do it

[21XDC]

Sounds electrical

[mactlman]

Sounds electrical

maybe a coil or ign module is hot soaking?? have seen crank sensors be temp sensitive also-- can run on muffs and heat the ignition component's with a hairdryer and see what happens don't electrocute yourself though!!!

[fishmaster]

I know it’s not quite the same motor but I had a merc 175 efi that would do the same thing. It ended up being the ECM. It would fire and run perfect one minute and next you would be riding along and it would just shut down. Sometimes it wouldn’t fire at all. Was just like the kill switch was pulled. Progressively got worse too. ECM’s were very hard to find at that point so it ended up getting taken off my boat and I replaced it with an opti. Hopefully that’s not your issue but it sounds exactly like what mine was doing at that time.

[mactlman]

https://www.bbcboards.net/forumdisplay.php?f=7
here if it is a 3.0 merc

here if it is a 2.5 https://www.bbcboards.net/forumdisplay.php?f=6

[GSM]

I posted it on the Mercury motor page but not that one

thanks for your reply. Have to check the ECM

[RngrPilot]

I had a Merc 2002 200hp efi that would do it. Running fine and then just shut down. Happened several times while at or near WOT. Mine would have a very short horn beep sometimes when it would shut down. I would sometimes crank up and sometimes not after the shutdown. Local shop finally found it was something like the main wiring harness connection. It took about 5-6 different visits to different shops to finally find it. Thing that made mine hard to find was it wouldn't do it all the time. Good luck

[Highcentered]

I've been there with electrical issues on an EFI. Turned out to be the computer. Shutting down at or near wot felt like the boat was running aground

[howkitz]

Ecu connector

[Rangerdeepv]

Freakin' computers! Hope this problem gets resolved and soon!

[Sweetolbryan]

Pull your ECU connector apart. Look carefully at the pins and sockets. You are looking for a pin/socket that is black and burned looking. If you see it, it will usually be the ECU ground wire. You can usually plug/unplug the connector several times and it will connect enough to start working again. For a permanent fix, find the wire coming into each side of the connector and slice in a new wire on each side with a connector in the middle. That way you can bypass the factory connection and still have the capacity to take the ECU loose. Since this is the internet, you can also replace the ECU and the complete wiring harness on the motor -“that’s the only way to fix it right”

[GSM]

I will give it a try.

thanks for the help

[drdriver]

My 250 Pro XB would occasionally do this. After doing some research and adding redundant grounding wires from ECMs to engine block, issue solved. Hope this helps.

[chad202]

ECU connector, main harness connector, or kill switch.

[GSM]

The nut that connects the ECU harness together is on but broken
maybe allows the connector to come loose enough to break contact ?

[howkitz]

The nut that connects the ECU harness together is on but broken
maybe allows the connector to come loose enough to break contact ?

Tie it together with zip ties

[GSM]

I will try that

thank you

[Rangerdeepv]

Check the starting battery too. The Opti's are pretty finicky about starting amps or lack thereof.

[chad202]

Tie it together with zip ties

Definitely need zip ties. Put one on the top cable and one on the bottom, then pass another one from top and bottom. Never have to worry about it coming loose again. Also, the main boat harness, pull it apart and get a very small sharp screw driver. The male prongs are split on the ends so gently pry them open slightly to make a tighter connection.