My 1985 Nissan pickup 4x4 will not stay running and then will not start for a long period. Several new fuel pumps were installed. Is it the after market fuel pump?

The accelerator pump in the carb could be bad.

Should be in the fuel line near the intake if it is a 4 cyl.

Did you hook all the lines for the fuel pump up when the engine was re-installed? It is definitely a fuel issue. Disconnect the fuel line and crank over the engine to check for fuel supply.

Possible problem with the fuel settings as the idling is faulty. So you will need to set the engine after a full check up on the fuel settings starting from the tank, the fuel filter , pump .
The idling setting must match the fuel settings.

if it has an electric pump on the frame by the tank it is in the fuel pump turn big nut on bottom of pump pull out cartridge type filter.

Alright, i have a 1987 Toyota 4x4. it has a 22RE full injected motor..it was able to run, but it was running rich, and idling pretty eratic..and then now..it only starts up..and dies. after like 5seconds. 

here ya go.

Fuel filter

Check in the fuse block to check for the fuel pump relay.