4hp 1996 Johnson problem

[Psycon]

Hey all.
So I have recently acquired a Johnson 4hp 1996 outboard. When I first took it out it would run but got bogged down and died and I couldnt restart it. I serviced the carb and found a lot of crap in the fuel filter, so i replaced the fuel filter and cleaned the jets in the carb. The second time i took it out the tell tale stopped pumping water out of it which cut my trip again. I decided that i would fit a new water pump and changed the gear lube while I was doing it. I just took the engine out again and it will run half throttle no problem but when I open her up it will run for about a min but then bog down and almost stop, unless I put the throttle to idle otherwise it will stall. The water coming out of the engine is pretty warm but not hot although when I checked the head it was hot but not bad enough to touch, but not as hot as the spark plugs. I am now thinking could it be either overheating (not so much now I have had a think about it) or it's a fuel problem where the bulb is draining faster than it can fill at full throttle?? I have taken off the fuel pump and it doesnt look like any splits or holes in the diaphram. Btw while I had the gearbox off I did put a hose onto the water intake and water came out fine. Its beginning to get frustrating
Thanks

 

[CLB]

Clean carb again would be my first option.

 

[Psycon]

I will take it off and give it another clean and double check everything is clear

 

[Psycon]

Ok I have stripped the carb again and it's all clean. Put back together. I am using the build in fuel tank and thought it was going through the fuel pump. This doesnt seem to be the case. The fuel pump only seems to work with an external fuel tank so it rules out the fuel pump as an issue.
On a side note there is a fuel bladder that sits where the fuel pump goes into the float bowl. When you blow into this tube you cant blow into it. It looks like the bladder blocks it. Is this supposed to happen?

 

[Psycon]

Just a quick update. I bought an external fuel tank and have taken the boat out for a few hours today. Its had no issues at all so fingers crossed the fuel tank has solved it ?

 

[A_8]

I was going to say you probably have an air leak or blockage in the fuel supply so if you find it you can still use your old tank.

 

[gordmac]

Is there a filter at the tank before the shut off valve?

 

[Psycon]

On the outboard tank there is a fuel filter before the fuel shut off switch yes but I have replaced that as it looked a bit clogged and I thought this was originally causing the issue. It did stop the engine stopping randomly though so was causing a little issue before I replaced it.