1996 Evinrude 200 Ocean Pro

Hi, I have a 1996 Evinrude 200 two stroke that I recently purchased. The guy who owned it before me let it sit for a year or so. I had a mechanic pump out the fuel tank, rebuild the carbs and replaced the impelar and housing (warped). I replaced the fuel lines and anti siphon valve inside the fuel tank. SO, the ISSUE is, the motor runs fine when sitting on the trailer in my yard. However, as soon as I put it in the water it keeps shutting off. Once I do manage to get it to take off, the boat will run from 1/4 to 3/4 throttle, but if I try to go above it starts raving like its starving for fuel. At idle speed it shuts off as well as in neutral. I noticed that the inline filter constantly has air in it. I also replaced the fuel pump, but no luck....thoughts?

Is it possible that the mechanic messed up on rebuilding the carbs? When running there's fuel flow, but doesn't seem to have a good prime. Eliminated everything from the tank to the fuel pump.

Til I am blue in the face.....

Throttle bodies. Search my username and subject "throttle bodies".

You can also try pressing the key in to activate the choking system while you are attempting to get on plane.
That will richen the mix, and if you feather the key presses just right, you might be able to get it up to speed.

Inline fuel filter under the hood always has air in it. Normal. Primer bulb always goes soft after the engine starts. Normal.
What is ABNORMAL with the primer bulb is if it NEVER gets firm, or if when running the engine fuel pump sucks it flat.

Primer bulb doesn't go flat and the inline filter stays about half full, but gets sucked dry when the motor is in the water.

Throttle bodies now replaced. When you look at the six carbs on the front, does it matter how they are plumbed for fuel? The top hose (off the fuel bar that runs vertical between the two sets of carbs) isn't going to the top carb. Could that be the issue?

No not likely.
Are you saying the engine is starving for fuel? Because filter goes dry and engine will not spin up....is that the basic problem?

If so, try pumping the primer bulb when underway. If the fuel pump and incoming fuel supply is weak, using the primer bulb to force fuel into the carbs will show it.

It keeps shutting off when loading and unloading from the trailer. I have to throw the throttle in gear so it doesn't stall out just so I can get it going. As long as I stay above idle speed and below full throttle, it runs. If I go full throttle it starts reving up and down like it's trying to go faster, but trying to stall out as well.... I'm really stumped! It sucks the inline filter dry and I pump the primer bulb but doesn't matter it still shuts off. It's not pulling enough fuel in when running under a load.

Somebody else jump in here. Maybe recommend something different.

Try running it on a 6 gallon gas tank, hooked directly to the motor. I would guess your problem is venting and/or the plumbing from the main fuel tank. I have also seen too soft of hoses used that absorb fuel pump pulses causing low flow and fuel pressure at carbs. Also problems with squeeze/primer bulbs.

At this point, it is a good idea to go ahead and do two basic tests on it to rule out other problems.
Do a compression test on all six, and post the individual numbers back up here. Not just "Compression is OK". I want to see numbers.
Second, do a spark gap test. Get a spark gap tester...10 bucks or so at auto parts store, and check that all cyls' spark jumps at least 7/16" while cranking
with all plugs out. If the starter gear jumps off the flywheel, just put a couple of plugs back in to provide a little load to the starter as it cranks the engine.

If those tow are OK, then concentrate on fuel delivery. timguy has an excellent suggestion. When using a separate tank like he suggests, be sure to use 3/8" fuel hose, and if at all possible, NO QUICK DISCONNECT fittings.