So I did I fuel pressure test today and got some bad readings!

First off I replaced the pump(acdelco) filter and replaced all my rusted out fuel lines so the system externally is solid.

Also a side note, I pulled my upper plenum to clean up inside of there(seafoam did an awesome job a week prior) so I couldn't see any signs of washing but it did smell potent of gas.

Now I didn't write down my exact numbers, at first connect I had about 15lbs after the motor being off for 5 minutes.
After priming the pump I came up too about 30, turned he key off, reprimed came to about 35-40
When I started the motor pressure eventually rose to about 50 give or take 2psi.
Then I read the gauge as I gave the car about a quarter throttle and it dropped to about 40 under load.
After that with the key turned off pressure dropped to about 30 and seemed to very slowly drop off after that.

I've read that these motors don't like to start on such low pressure which puzzled me, so is the problem that the fuel pressure regulator will not hold a high enough pressure? This is my best guess but it's still not the cheapest of parts to just throw at the motor. Any help or questions are greatly appreciated!

Side note: will fall on its face past 3/4 throttle and kind of wants to die on first startup usually and sometimes after it's been hot it will want to die more on a restart.
Only code is p0452 which I believe is a purge valve that never had any real effect on the car since I bought it.

 

This link explains how to test the fuel delivery system:
https://blazerforum.com/forum/2nd-ge...eakdown-88305/


Post all 4 readings and we can help analyze them.


Year, make, model, engine would be helpful too (they're not all the same).

 

Sorry was in a rush when I posted this! It's a 2000 blazer 4.3 with an already upgraded mfi spider. I won't have the tester again for a day or two but ill try and get those soon as possible!

With that said though would you also lean towards the fpr as it is potently smelly in the upper plenum in addition to the very low pressure?

 

P0452 is a fault in the fuel tank pressure sensor electrical circuit.


If it fails the leakdown test at the service port, something is leaking. It might be a fuel pressure regulator, but no guarantees without more testing.


You'll need to build the adapter to test pressure and leakdown at the fuel filter outlet. This is mandatory for a complete and accurate diagnosis. There is a parts list in the link with all of the necessary parts, and where to find them.