No fuel pressure 1994 4.3 s-10 Blazer

I R&R the fuel pump and the filter but still have no pressure at the Plennum. I have searched in/out for a fuel pressure relay/sensor or a fuel pump relay. Pump comes on for 5 seconds then shuts off. Need location(s) of these electrical relay(s). Vortec 4.3 (W) engine code. Thanks.

GM usually puts the relays on the firewall, might want to pick up a Haynes manual to be sure which one it is, however it sounds like your pump is bad. The pump only kicks on for 2 seconds then shuts off until your engine starts. It is supposed to build up suffecient pressure in that amout of time to start your truck. If order for the folks here to help you should advise engine size and type(if it is a 4.3 advise if a Vortec Vin W or a TBI injection type). makes a world of difference on pressure needed to start your engine... You may have been sold wrong pump too. Not first time that has happened. A 4.3 TBI motor only requires 12lb or so of pressure to run. A 4.3 Vortec (CPI injection) requires 55-60 lbs minimum to start... If you have a Vortec and a TBI pump, it won't work.

if you hear the pump then the relay is fine, thers another problem somewhere

Have you checked your CPI and nut kit for leaks?

GM usually puts the relays on the firewall, might want to pick up a Haynes manual to be sure which one it is, however it sounds like your pump is bad. The pump only kicks on for 2 seconds then shuts off until your engine starts. It is supposed to build up suffecient pressure in that amout of time to start your truck. If order for the folks here to help you should advise engine size and type(if it is a 4.3 advise if a Vortec Vin W or a TBI injection type). makes a world of difference on pressure needed to start your engine... You may have been sold wrong pump too. Not first time that has happened. A 4.3 TBI motor only requires 12lb or so of pressure to run. A 4.3 Vortec (CPI injection) requires 55-60 lbs minimum to start... If you have a Vortec and a TBI pump, it won't work.
Thank you jsgold, Engine is 4.3 Vortec (W) CPI and not to mention, I have been R/R with used pumps ($$$) not any more will be getting a new pump in the Morning. Thanks. Dilydaly.

if you hear the pump then the relay is fine, thers another problem somewhere
Thanks dmbrisket 51, I think I have to buy a new pump instead of R/R with used ones first, then go from there. Thanks. Dilydaly.

Have you checked your CPI and nut kit for leaks?
Thanks rlith, not at this time, after R/R the pump with a new one, then I will check for the leaks. Thanks. Dilydaly.

Thanks rlith, not at this time, after R/R the pump with a new one, then I will check for the leaks. Thanks. Dilydaly.

If the pump is priming, then look for the leaks, they are probably your problem...it's probably a leak down after the pump primes...

cpi, 50-60 lb system, you would know if there was an external gas leak, a leaking nut kit makes more sence then gas seepage

Have you checked your CPI and nut kit for leaks?

Just to add. Have you also replaced your fuel filter. If it s clogged. You won't get any pressure either.

Just to add. Have you also replaced your fuel filter. If it s clogged. You won't get any pressure either.
Thanks Gabe25, I sure did, pump and filter R&R. I was going to check for leaks today but,...... didn't. I will in the morning then let ya all know the out come. Really appreciate all the help. Dilydaly.