2.5 mercury afraid of water

[Kwa]

Hi fellows, I'm new and lost. I've got a 1996 mercury 2.5 ltr. 200hp efi. My 2nd and last mercury.. I have receipts for last 3 years around 2500.00 that I've lost looking a so-called mercury mechanic. It starts fine in yard on water hose,run hour at the time, no issue. Starts fine every time. Take it fishing, starts up fine, run it long as you want, fine no problem. Cut it off and fish for an hour, WILL NOT START. BY SOME CHANCE IF IT DOES FINALLY START, it RUNS RAGGED and smokes like its on fire. Plugs soaking wet with fuel and oil. Put it on trailer and come home ,you can walk by and touch the key, starts right up. Thing i have one thats scared of water. Can anyone help. About to give up. Thanks

[Merc 2.5]

Electronics, need run timing lite on it in water when starts acting stupid

[Kwa]

Electronics, need run timing lite on it in water when starts acting stupid

If you clean and dry or put new plugs in , it will start

[Merc 2.5]

Have you checked for spark when it's running rough

[H2OPERF]

Maybe vst overflowing or diaphragm pump leaking into block...

[Kwa]

Yes, there is spark ,I keep another set of plugs in boat. Put new plugs in and it starts.. new diaphragm/fuel pump, supposedly replaced by mechanic. Oiler was unhooked before I bought it. Run mix in tank 50/1. I've asked if that could be the problem and was told no.

[CircleHook]

Pull the efi off and put carbs on it.

[rock]

Check your temp sensor. If it is telling ecu it is cold then it will add gas. After it is warmed up that extra gas will keep it from starting and that is why new (dry) plugs will let er eat.

Rock

[XstreamVking]

New mechanic needed, not a diff motor. These motors are very reliable when they are in the hands of a competent mech. I think there is a fuel problem with flooding, like the needle /seat.

[RSWORDS]

As with what everyone else said also check the stator when hot. I've had a couple that where fine until you ran the boat a while and then cut it off allowing it to get heat soaked.


And yes, time for a new technician

[Kwa]

Thanks everyone. Yes the stator has been replaced by one of these mercury mechanics or at least he said he replaced it. Everywhere I've carried it to only runs it on a hose or in a tank, yes I do need a mechanic, but havnt found one in eastern n.c. that knows anything about mercury. All the normal every day fixes have been tried and sometimes twice. Keep hoping to stumble across something that will help.

[Merc 2.5]

All the things that the so called mech worked on needs to be looked at again , just because they told u 1 thing doesn't mean they even looked at it , I'd start looking at all things we have said again, prob lies in fuel or spark my .02

[Kwa]

Thanks

[H2OPERF]

I would def check the vst, (small tank on the side) this gets filled from the diaphragm pump and has a float/needle and seat like a carburetor to keep it full and if i remember right the vent goes to the intake. ..make sure its not overflowing, regardless of whats wrong a flooded or super rich engine will act way worse in the water with back pressure on the exhaust than on land where it can clear it self out .. Dave

[Kwa]

Thanks Dave.
I looked at it and don't really know what to do to it or how to check it. I'll try to find someone who does. Thanks. That's probably one thing no one has looked at.