4.3L rebuild engine will not stay running.

[garrett113]

Hey guys. I'm hoping to get a little help in figuring out my problem. I have a 1990 omc 4.3 l it has a Holley 4 brl carb on it which is how I bought it but not how it came originally. So most of what I have is new, it's a refurbished long block, new coil, new fuel pump.
My problem is that I have to pump the carb a few times then keep throttle about half way open to get it started then it is very rough and will die once I left off throttle.
I am thinking either a fuel issue or vacume leak. Any ideas?

 

[alldodge]

I am thinking either a fuel issue or vacume leak.

I would also add maybe low compression.
How do you know the long block was refurbished?
When its running can you see fuel leaking into the carb?

 

[rs1lollie]

have you checked the timing???? I bought a boat that a sports shop had on consignment that they put in a new long block, i had similar issues, so i gave it a tune up, (plugs, wires, cap and rotor). i read that with volvo's you need a timing shunt to time the engine, My timing was way off when I checked it,( I dont think they knew that when they timed the engine). I made the adjustment and now it starts without pumping the throttle, idles smooth and quick throttle response....