I have a 1996 chevy blazer that started out kinda sluggish so I replaced the fuel filter. I have also put a new battery, altenator, and water pump on. Now it wont start at all unless i put gas in the carb. Once it is running it will stay running and if you shut it off, it WILL start as long as you dont leave it for more than a couple hours. Then you have to put gas in again. The fuel pressure is at 50 psi. I know it should be at 60-66. Just wondered if it would make that much of a difference. Fuel is getting to the fuel control module, but obviously not any further.
Sometimes after a couple hours, it does have trouble starting, but if u turn the key on and off a few times it gets enough fuel to start up again. Thats why i wasnt sure it was the pump.
Not sure what to check, was thinking it was either the pump or the spider module. Any ideas would be great! Please help!

 

Check out the Tech Article (DIY) section for the fuel pressure test procedure (link to the DIY article index is in my signature).

 

DIY fuel pressure regulator on Blazer 4.3L CPI engine? Is that the section you r talkin bout?
Would the fuel pump pressure at 50 psi, make a difference? or just that the pump is weak? And is this a common problem for the 4.3 vortecs? cause it is showing a misfire malfunction (engine light stays on)

 

96+ Fuel System Diagnosis

 

Carb? I thought all the Vortecs were fuel injected. Where are you putting the gas exactly?

Anyway, if you have a fuel injected Vortec, 50 psi sounds too low to me. I've had to change the fuel pump on my 95 for similar symptoms. Would be very difficult, almost impossible to start. Once running, it would stay running but be very sluggish at times.

After you turn the key and activate the pump, without the motor running, the pressure should hold steady. If it drops, you need to follow the posted procedures to determine if the problem is in the pump/tank area or in the engine/spider area.