The question is what kinda carb is this , is this carb new , rebuilt , --- if so is the float level correct?

Go for the obvious first and change the fuel filter. It's quick, easy & cheap to do & is the most common cause of the problem that you have.
If problems persist, see a [car] doctor. NO, if the problem remains, then you need to find the reason why more fuel flows through the main jet at full throttle, than flows through the fuel system, but my money is on the filter.

As for checking fuel pump, have a look at this,

http://datsun1200.com/modules/nsectio ... p?op=viewarticle&artid=34

Rubber mount the electric fuel pump and it wont be so loud.

ok so how do i check my fuel pump. and wats involved with puttin an electronic pump in. a mate got 1 put in his ute and its so loud. just a constant ticking but like you can hear it 10 metres away. is that normal or somethings wrong, cuz i dont wont mine goin like that. thanks 4 your help

4th gear puts the most load on the engine, this means it uses the most fuel. if its stuttering like that i'd say it was starving. check ur fuel pump, it might be a lack of pressure. it wood only be in 4th gear coz of the load on the engine which - as i sed - uses most fuel. if the pump is faulty, it might be time to upgrade to an electronic one.
u dint mention a turbo charger so i spose its not wastegate settings or turbo lag.
and if its a N/A engine then about 4psi is heaps to run it.

Tommy

I have experienced similar thing.
Mine has Hitachi flaptop SU's on it.
When I push it hard up to 6000rpm full throttle in first and second gear it pulls strong.
When changing to third it also pulls strong, but I noticed when in third gear full throttle and I lift my right foot about 1/4 from the throttle so that it is not wide open but a little less, the car pulls stronger than full throttle in third gear.

i have decided 2 start doing things myself on the car, but for this problem im going 2 need some help. I will go through the problem. when im giving the ute all its got, eg taking up 2 6000 before changing gears. i go through 1, 2nd and 3rd, then when i get up to 4th the ute sorta either starves itself or floods its self. it seems 2 be starved of fuel to me. i just let it coast a bit and pump the peddle and after about 5-10 seconds its back up and running. its only when your flogging the engine but. What could be the problem here. my carby seems to be tuned pretty good. anybody got any ideas???