2002 3.0 Merc not running on water
Good afternoon all! looking for a little insight or a lot of it. I'm pretty new to boating so I apologize in advance if my terminology is off a bit and sorry for the long winded post but I feel like its best if I put the whole story out there.
Just bought a 2002 Maxum 1800 SR last summer. It ran pretty good 5-6 times I took it on the lake. One day in the late summer I took it out warmed it up and backed it out of the dock area, threw it in forward and got to cruising speed once I hit about half throttle it died. I could not get it started again after that. The season was almost over so I got towed in and took it to a garage where they rebuilt the carb and winterized it. (it apparently ran at that time with the hose hooked up to it).
This spring when I took the cover off apparently I had water frozen down by the engine. when it thawed out I looked everything over but nothing at face value appeared damaged. I was having a hard time getting it running after that, basically it would start but not stay running. So I took it back to the garage, they found a fitting near the top of the gas tank was cracked so I was thinking water got in there. They "drained" water out added some dry gas and got it running. They said it ran for about an hour no issues, I took it back to my house, then hooked the water hose up and tried it myself, It started right up and ran for a solid 20 minutes in neutral, forward and reverse under various throttle positions....so now I'm pretty confident.
I take it to the lake start it up with the trailer in the water its running (wonderful!) I back it off and warm it up another couple minutes then throw it in forward and head out, I get to around half throttle seems to be running perfect then all of a sudden it dies right out.... (now I'm f'in pissed). So I towed into a dock on the local lake that repairs boats.....Ill try this. So they tell me theres a ton of water in my gas... so they drain the tank, put more gas in and some extra dry gas for whatever water is left oh and also clean the carb and reset the floats (for a bill of $600 fml). whatever as long as it runs now right? WRONG.
I go to pick it up they are confident in their work, I back it out in to the bay with the mechanic in the boat, takes a little time to warm up and again went from reverse to neutral to forward, this time as soon as he puts it in forward it dies... now it wont start again...... guys I am lost and its becoming a money pit. any help would be greatly appreciated. hopefully someone reads all of this