Hi all,I have a problem with my 2000 blazer with the 4.3 vortec engine.Just before christmas eve the fuel pump died,I got another from a junkyard installed it and still no go. After check the feul pressure come to see that I only have about 40psi.I was told I need a min of 50psi to start,and that I may have gotten the wrong pump.Cause gm has different pumps some that have 35psi and others that use 60psi. Any input would be great.

 

All fuel pumps from GM for a 2000 4.3L should be designed to run at the correct pressure for your engine. If in doubt get a new one from rockauto, but make sure it is either AC/Delco or Delphi. Any other brand and you're asking for trouble.

 

Checking fuel pressure at the service port with the pump running and the engine off, indicates what regulated fuel pressure is. 40psi is a problem, it must be 60psi to 66psi. Your reading of 40psi does not necessarily mean the pump is bad. To check the fuel pump, you need to check maximum pump output pressure by making all fuel flow and pressure end at the pressure tester. The easiest place to do that is at the fuel filter. It should indicate 73psi to 108psi and remain above 55psi for at least 10 minutes after the pump shuts off.

 

Right now the truck will not start. I was think it could be a problem with the pressure regulator. But one minute it was fine I parked went into a store come out and no go.The pump wasn't priming. If I put gas down the throttle body it will fart and sputter. I think I'm going to get a new pump tomorrow. There is a pressure senser on the pump,if the was bad would it still start?
I will check the pressure at the filter before changing the pump. The truck has been in my garage for a week now between stores not having parts or being closed for the holiday or me working it's been a pain in the butt.

 

if you got a pump out of a junk truck, you should've checked the miles. Anything even near or over 100k and there's a 90% chance it's dead or headed that way. Plus, it sitting for who knows how long... bad idea.

Second, there are different pumps for 2 door, 4 door and S10 pickups - and they are not interchangable.

Third, I'd have to wonder if your original pump is dead, or is it just a plugged filter? When I replaced my pump at 147k, I also changed the filter. It was the original, and it was flowing maybe 30% compared to the new one.

 

With the engine attempting to start, (farting & sputtering) confirms that the fuel pressure is low. The pressure sensor on the fuel pump module is for the EVAP system, (evaporative emission system) and will not keep the engine from starting.

 

Hi, I did change the filter and it made no difference in the pressure test. I didn't know that all the pump were different. I have gotten I lot of part for junkyards in the pass without a problem,but it does happen. The part place is open this morning so I'll be headed over short to pick up the pump.

 

Ok I got the new pump in and the truck starts now,I have 80+ psi at the filter.But now it's running rough. And the check engine light was flashing, I plan to check the codes as soon as I can get my hands on a reader. Well its new years eve, I guess I just go have a few drinks and work on it tomorrow. Have a good one.

 

I checked the codes and I got a P0304 (#4 misfire). What could be causeing this ? I didn't have this before,it was running fine.

 

Most common problem would be a fouled spark plug or a bad plug wire. Try swapping the plug & wire with another cylinder. If the DTC changes cylinders, you found the problem.

This thread will help: https://blazerforum.com/forum/diagno...4-5-6-a-35153/