Mercury dies throttling up

2003 200 EFI Mercury usually runs OK heading out to fish. Shut big motor down troll for awhile. When it's time to come back in or move to another location, it starts right up, throttle up and engine dies, start up throttle up and engine dies. Runs fine at idle, but it dies when I try to get up on plain. I had in at Merten Marine in Oshkosh twice. They keep the boat for more than two weeks each time. Payed them over a thousand dollars and it still doesn't work. Anybody have any suggestions?

I agree, does not sound like a fuel delivery problem.  

Sounds like a electrical problem, maybe a module heats up wire separates, motor quits, motor cools and runs again

Thought I would show you the boat.  For a couple years now I always say 

Boat looks good but runs like crap.     Bummer 2 years still didn't figure out why it shuts down

Well to boat in needed a impeller and I thought to switch the throttle ass. because the run shut off switch was giving me trouble once a while..

Took boat out sat. on winne. made it 2-3 miles and motor shut down. (like turning key off) switched that also. Had to fish the rest of the day with kicker big motor wouldn't start. Last night in the driveway motor fired right up. Had it at Boat Doc 3 times so far. They can't figure it out because motor works fine when I take it there. Going to run a external tank to see if its the line from tank to gunnel. When it shuts down the bulb is still hard so I don't know. WHAT THE HECK  I wish something would just break so it could be fixed!!!!!!!!!

Yes my kicker runs off hose and yes bulb is hard. I replaced the fuel line from the gunnel to motor but not the tank to gunnel switch. Ran gas with alcohol also.. Boat stored now, In spring I'll put new line from tank. Thanks and Happy New Year.  God Bless

I think that the fuel line is the issue also. If you have run gas with alcohol in it it has probably started eating the inner liner of the gas line up and cause it to starve the engine of fuel.  does your kicker motor run off of the same tank? If you check the bulb on your fuel line is it good and hard. 

LarryAllen. I suggested the spark plugs as that was my problem after trying various other things. Strange, but that was the culprit. Glad you're is running good like mine is.

Had the same problem and all it was the fuel li e connection to the engine. Put new one on all better.

Good luck 

I have a 2002 200EFI mine does it also. Mine happens when running full speed like you turned the key off! Get ready for the wave coming over back.  Took it to Boat Doc in Lomira 3 times they can't figure it out because it will not shut down. The one time I took it to winne with gas pressure gage and cdi module. If it shut down see what the problem is. Well it ran so good and never shut down.. Next time it shut down they said keep cdi for spark plug and switch it to see if starts. I changed every one and it didn't start.  If I wait 10- 15 min. it fires right up like nothing wrong. So for now its in storage and nothing was fixed. 

I had a similar problem with an Evinrude 40hp 4-stroke (Suzuki).  A Lake-Linker suggested that I replace the spark plugs even though they looked good.  I thought what the hell it was worth a try.  New spark plugs solved the problem.

Could be the power pack. I had an Evinrude Intruder a while back and it behaved similar - it ended up being the power pack.  

I had the same problem on an older Johnson. Mechanic tried several things..cleaned carburetor, replaced fuel pump, replaced tank primer bulb, no luck.  I decided to replace the spark plugs. That was it.

Are you running a kicker off your main gas tank?

I have an older Mariner 15 hp I bought used 10 years ago.  It calls for a 40 to 1 oil mix.  It would do what you are describing, wouldn't pick up speed especially after being run for a while, even though it starts very easily.  After several years of this aggravation, I did some research about oil mix.  I admit I was not super accurate on the measurement, especially when I "topped up" the fuel tank with a couple of gallons.  I am diligent on my measurements now.  And although I am not a technician by any stretch, and you need to do your own research, the recommendation was to go with a 50 to 1 mix for my motor.  I've done this all of 2018, and the motor has never run better.  Hope this provides another perspective.

If possible bring a separate tank with you. If it acts up use separate tank with a new gas line see if that fixes issue. If it does its a gas supply issue with less than full tank of gas.