Hello Everyone,
This is my first post. I will do my best to make it as clear and detailed as possible in hopes that people here will be able to help me in pinpointing the problem(*).
Thanks
Current Problem-
My 1994 Olds 98 Regency 3800 stalls quickly after starting.
What we know-
-Fuel pump operates when supplying 12 volts to the test connector by the battery and enough to start the car when turning the key.
-Fuel pressure is between 10-14psi.- We tested fuel pressure first connected to the fuel pressure regulator ( 10-14psi) Then we rigged the fuel pressure gauge to connect to the fuel line before the fuel rail and FP regulator test fuel pressure. The result was the same 10-14 psi. Usually closer to 10 psi. Last week it was 15 psi and the car would stay running but stall when driving to drive it.
I finally found the fuel pump relay though I haven't tested it yet. Do I feel it to see if it gets hot? Do I check anything related to the relay with a multimeter?
I want to test voltage and ohms in the wires going to the fuel pump before I buy a fuel pump. I did read that a car with my symptoms still had the same problem after replacing the fuel pump and it turned out to be a ground block issue near the kick panel inside the car and under the carpet. I don't know where to pull up the carpet nor what to look for.
Does anyone have any ideas or suggestions?
Thanks!
What we have fixed, replaced, cleaned, or checked-
Replaced fuel filter
Cleaned EGR valve
Replaced o2 sensor
Replaced Coil Pack and Module( used )
I don't remember the codes from the first test.
The most recent codes were
P0131 bank 1 #1 oxy sensor circuit low voltage
P0300 Random misfire
I cleared them after replacing the O2 sensor.
Checked the fuel pressure regulator. It seems fine.
The problem started about a month ago. After driving it about 30 minutes, parked it, shut it off, shopped 30 minutes, then had a difficult time starting it. Drove another 30 minutes, let it idle while I went shopping, came out to see the check engine light on and car not running smooth with very little power to drive it 2 miles home. For a week or so the car would start fine ( if cold ( and fun for 20 minutes or so before the check engine light would come on and engine would lose power. Then last week it started hard and didn't run smooth even when cold but I could drive it 50 ft into the garage. Now it starts hard and stalls right away.

I bought AutoXray EZ-read 2000 AX2500 with the special 16pin blue ODB1 cable for the 94-95 GM'*.
I also used the ALDLdroid & ALDL Scan tool apps with the 16pin Bluetooth ALDL ODB1 cable from 1320electronics for diagnostics.

I think you are suppose to be seeing something around 40 psi for a 3800.

Yes that sounds about right. Thanks
What I am wondering is if the fuel pump is failing or could it be an electrical issue causing the fuel pump not to work properly.

How good are you with diagnosing electrical systems?

I am surprise it is running at 10-14 psi.......sure pressure gage is ok?

One way to test the circuit, disconnect the harness to the pump, attach a test light to the harness half fuel pump circuit, not going to the pump.....now ATTACH A VOLTMETER in parallel to the test light...... should get the same voltage(less a few tenths), you would get across the battery while cranking with fuel pump disconnected....

If the voltage is ok, still have to check the FP regulator first.....is there fuel in the vac line? If no, then next step is to block the return line(if you have plastic lines, you need a special tool, an inline valve......if fuel hose, just clamp with vice grips).....with the fuel pump harness reconnected, cycle the key to on....wait 5 seconds, then shut off for five seconds....repeat this several times.....does fuel pressure build up to normal? If yes, then you need a regulator...if no, a pump, since you said you replaced the filter and the voltage at the harness was ok....

I am new to this so the answer is "not good" lol

Thanks.
I can use the gauge on my dad'* gmc truck to see if the gauge works properly.
I am not sure I understand your step by step guidelines but I will try tomorrow. Hopefully when I am with my car and multimeter in hand I will be able to figure out the testing procedures.
There hasn't been any gas in the vacuum lines.
I will update tomorrow after I try these things.
Thanks

The reason why I insert a test light into the fuel pump circuit of the harness half going away from the fuel pump is, to LOAD the circuit......and then I attach a voltmeter to see how much voltage is actually getting to the load or fuel pump......if instead, you just attach a voltmeter, all you are reading is voltage potential, because there basically is no current flow.....

For example, suppose you have a bad voltage drop in the f/p circuit due to a corroded connection......if you attach a voltmeter only, it will show an open circuit voltage close to battery.....now install the test light, and voltmeter, and you might get a much lower voltage because there will be a drop across the test light, AND also across that bad connection......thus the f/p is not getting full voltage to it.....

What part of the world does this vehicle live in?

Does it do more highway driving or city driving?

What does the odometer say right now?

Do you keep your fuel tank more than 25% full all the time?

How many miles since the fuel filter was replaced?

How many miles have the current spark plugs been installed?