Pressure is too low and leakdown is excessive. Provided there are no external fuel leaks when the pump is running, the source of the leakdown could be in the plenum or in the fuel tank. To determine where you start looking for the leak, the fuel pump must be isolated from the plenum just after it pressurizes the system. The results will tell where the leak is, not what is leaking. What thread were you reading and what do you have a question about?

 

i was looking at thread that is written by swartlkk. I did the step 2 and then 11 and than 21 because the fuel pressure is not constant. it says replace the fuel pressure regulator. Im not a mechanic so I dont know how to replace it. is it really hard to replace it and how do we do it?? thank you

 

the fuel pump in the tank has a check valve built in and it sounds like it went out i would just get the ac-delco rebuild kit for the pump and get some fuel injection rubber fuel line cuz the the plastic factory line never stays on and you cant get it on like the factory does... the injection fuel line is like $8 for a foot and thats about how much you need... you will need to notch out a little spot in the sending unit to get the hose clamp on but its no big deal

besides if you dont have 60PSI it will not open the injectors on start up either

 

With pressure dropping to zero in 10 seconds, (as mentioned, but no guarantee) the fuel pump check valve is probably leaking. Checking maximum output pressure and watching leakdown is the only way to know for sure if that's the problem. Max output should be approximately 108psi and must remain above 55psi after 10 minutes. If the pump doesn't pass the test, it needs a new one.


Key ON, engine OFF pressure needs to be 60psi to 66psi when the pump is running. As pressure drops below 60psi, performance issues will get progressively worse: hard starting, hesitation on acceleration, lean misfires, lean DTC's, etc etc. When pressure gets down in the low 50's, fuel must be added in the throttle body to get the engine to start. When pressure drops below approximately 40psi, the poppet valves will not open and the engine will not run at all.

When replacing the pump, discard the old fuel line clips and install new ones, (the old clips are not to be reused).

 

YouTube - 2000 blazer
I did the test again so you guys can see what Im doing. are you talking about a fuel leak because i checked under the car and there wasnt any leaking. thank you for your help

 

With no external leaks, the leak is internal, either inside the plenum or inside the fuel tank.

 

ok so how am i gonna check the leaking inside the fuel tank. thank you

 

To do this, you must install a shut off valve, in the fuel pressure line at the fuel filter.

 

im pretty sure this is happening to one of my buddies so if you figure it out, plz share. does yours die while your driving?

 

I only have a problem when I try to start the car. It doesnt die. Its just hard to start the car but sometimes it starts normal. I really dont know what is wrong with it at this moment but help from these guy i will find out. Again thak you guys. Captain hook i was looking at the part stores this morning but i couldnt find that. do u know any place that i can get that. is there a diagram of the engine that shows where is vacuum line that attaches to the FPR. thank you