I did a pressure test, not sure i did it right. I hooked up the gauge and turned the key on, let the pump run for the few seconds as it normally does, then i turned the key back off so the automatic lights dont kill the battery. i left it for an hour it was at 50psi when i left it, and when i came back it was at 12psi. if i did something wrong please point it out for me guys, and if it was correct, is it either the injectors or regulator? or is there anything else that would cause the drop? or is that how it works to send back down the pressure?

 

it is natural for the pressure to bleed off when sitting. And if you still held 12 psi after an hour you are good to go. My only question would be what is nominal fuel pressure at the prime stage?

Massey

 

nominal being...? when i first turned the key the gauge read 50 psi, after that i had turned the key off and left the car to sit, on a side note i hooked the gauge on just after driving alot.

 

Nominal means what is the pressure supposed to be at that time. or what is the normal acceptable range?

Massey

 

i did an hour test again it started at 50 psi pump on, 1 hr later 13 psi. Im going to leave it and see where is it in half hour and 1 hr from now.

I thought its supposed to hold the pressure?

 

I think the range for these cars are 47-52 psi pump on engine off, and 58 psi running

 

The GM book test only requires the wait time to be like 5 minutes and the bleed off should only be a few lbs and if I remember right no more than 10 psi after 5 minutes. Like I said if you are holding 12-13 still after an hour your pressure regulator is working just fine.

What is going on that has prompted these tests?

Massey

 

I`ve been noticing the gauge giving me some incorrect readings as well as the car doesnt have the power like it did at first. so i figure maybe something is going on with the injectors or fuel. i have been trying different brands stations to see if im getting any difference in miles but it look like its the car and not the gas.


Update: after 1.5 hrs its at 4 psi

 

STOP with the 1 hour plus stuff, that matters very little. Who cares what your fuel pressure is when the car is off! This does not matter. Your system seems to hold plenty of pressure for the time it needs to hold that pressure.

Loss of power can be so many things, including but not limited to age of the engine. How is your air cleaner? when was the O2 sensors last replaced? What is the compression? Dirty fuel system, old plugs, bad wires, and a few other things. But fuel pressure at the priming stage DOES NOT effect the overall performance of the engine. Low prime pressure can cause hard or no start conditions.

Massey

 

oh..
well heres what was recently done less than 500 miles
4 o2 sensors
new air/fuel filter
fresh motor oil
new air valves
new delco iridium plugs/msd wires
tested back pressure before cats