My 1997 blazer won't start unless primed in the throttle body it runs fine after when shut off for a day it needs primed again

You'll have to do a fuel pressure test to see if the fuel rail is maintaining fuel pressure. If psi falls, it's either a leaking fuel injector, bad fuel pressure regulator or bad check valve in the fuel pump. Since you've replaced the pump, chances are it's one of the other two.

Maybe a problem in the fuel pump circuit. Check fuel pressure with engine off, and key turned to on, not start. If no pressure, diagnose the pump circuit at the fuel pump relay. One terminal for the relay would be the power feed for the pump. The engine computer signals the relay on for 2 seconds with key on to prime the system, also signals during engine cranking.

is your security key lamp lit on dash.

CLEAN THE THROTTLE BODY FROM ANY DIRT AND USE A SCANNER AFTER TO RESET THE THROTTLE.

Take the gas filter off. Should be located near the front of the carbeurator, take off the air cleaner and look for it, it takes 2 wrenches to take it off, a little gas may spill out but not much and replace it, however there is a strong possibility that he gas pump is out if the filter is fine. Hope this helps

I'm following another issue like this on a 1996 Jimmy.
This engine requires 60psi or more fuel pressure to run.
You need to have someone check the fuel pressure at the rail- throttle body with a gauge.

Have you had a fuel pressure gauge on it? It needs 60 psi cranking and aleast 55 when running. Sounds like the pressure is low. When you replaced the pump did you replace the hose between the pump and the hanger assembly?

if you can put fuel in throttle body and it runs. then it is not getting any fuel. check your fuel pump fuse and the relay, if ok, then you may have a bad fuel pump or a plugged up fuel filter. check filter and fuses first. good-day !!

The cam sensor,or pick up coil in the distributor is at fault,witch ever it has.

i have the same problem on a 98 jimmy 4.3 4x4.
i replaced the fule pump and have good pressure.
new wiers & coil (good spark) no MIL & no codes.
will only start when primed. it will run & drive all day
with no problems.
but once it has been turned off (warm or cold) i will
have to prime it once again to start it.
i have another engine that was in it before it spun a bearing.
it ran fine so i know all parts are good.
i swaped the mass air flow and throttle body but i still have
to prime it everytime to start it. am i forgetting something?
should i swap out the intake with the injectors?
any help would be sweet. thanks.