1999 225 efi help

[timscreteserv]

i'm new here so..anyway i just got a mercury 225 efi on a boat and it runs fine for a few hrs 1/2 tank of gas .. or gets hot then it seem like someone turns the key off .. but by the time it coast to a stop it starts right back up then it will go 300 feet or so and does it agin and agin and agin but it only happen after it is good and warm up or maybe 1/2 tank of gas (75 gal) ...anybody gone thur this before please help (change the ecu it not that) put new key harness on at the motor not that.. never does it on the way out only on the way in HELP

[Eagle One]

You may likely have an overheating issue. The engine has several sensors that will either cut the engine back to around 2500 rpm or either cut it off completely. You should change the water pump if it hasn't been changed in the last 3-4 months. You might also have a fuel pump going out which would cause a similar problem. I suggest you take it to a Merc dealer with a DDT meter(digital doagnostic tester.) as they can pull up a lot of info about what the problem could be. There is no "just check this wire" fix. Failure to find the problem with repeated running can cost you an engine.

[timscreteserv]

thanks for the reply...the temp all ways reads fine but it might be a fuel problem but you would think it would spit and sputter but it does not it just shuts off and you can start it right back up and go another 300 feet or so it shuts off agin and it does it agin and agin but it only starts shutting off after a hr or two of running it please help it's costs a lot of time and money

[Eagle One]

sounds like a sensor problem. Need a DDT to find it. Could be a pump or the ECU

[timscreteserv]

have a guy comming on Monday for another water test but he was the one that thought it was the ecu .. can he bring the DDT tester on the water test or only at a shop ? because I will tell him to bring it...

[hydro-cat]

Check the fuel line from the tank all the way to the engine. If by chance, it is the old Mercury sliver fuel line. It's inside line it comeing apart. There is still some of that fuel line around. Seem to have seen alot of that this year. Just a suggestion worth lookiong at.

[timscreteserv]

thanks hydro-cat i'm replaceing them now.(primer ball, and lines) weather they need to be or not trying to cover all my base's

[mkguyvr]

sounds stupid but check you tank vent, a clogged vent can cause a vacuum to build and stop fuel flow, check/ change your fuel filters, if you have the water sensor on the engine mounted filter this could be causing an issue.(water in the filter) Guy