Yes sugar bear I do have enough gas in the tank, fuel guage is working properly on the instrument cluster panel.
I got the fuel pressure gauge from autozone as a loan-a-tool. Although I had to pay in full for the pressure gauge, I can return it back to Autozone within 90 days and get a full refund. Good Deal! Set up fuel pressure gauge to the schrader valve port on the fuel injector rail (no adapter needed) as I assumed the thread on the schrader valve port is universal. Tight fit on the schrader valve port. Turn the ignition to on. Readings on the pressure gauge was barely above 0. See the picture below. I then proceeded to start the engine, same results on the pressure gauge readings. What did I do wrong? I suspect that the fuel pump motor is not producing power. There should be some pressure readings on the gauge. I need to investigate this issue further.
The fuel pump relay behind the battery is good as far as I can tell. The 30 amp fuse is not broken. However, I have additional spares of the same type of fuel pump relay. Will double check that fuel pump relay.
Afterwards, with ignition turned off and removed the Fuel pressure regulator hose to find out if the fuel pressure regulator is defective. According to sources, if there is no gas leaking or coming out of the fuel pressure regulator, then the fuel pressure regulator is good.
I am having problems trying to check the fuses and relays. I do have both the test light and the Digital Volt meter (DVM). I just need to educate myself more fully in understanding how to test the fuses and relays using the test light and the DVM.
It seems to me so far I have a lot of electrical gremlins/issues. The trick is to pinpoint exactly where is the location of the electrical problems, if any, and elsewhere. I try not to get frustrated and discouraged, just focus with a positive attitude and keep challenging myself that I can do this.
Also, while I checked the fuse box and the relays behind it, something caught my eye. Knowing that the parking brake, abs/asr lights on instrument cluster panel that started the series of issues/problems to begin with and the engine runs fine at that time. According to the fusebox diagram/chart, there is no relay for ASR/parking brake listed. See the picture of the fusebox chart. It is exactly the same as mine. I wonder if there is a relay for the asr/parking brake somewhere on my mercedes? See the video:
https://www.youtube.com/watch?v=SSugX9TZKc0. Notice as the descriptions of the fuses and relays and its locations, See the Relay I and the descriptions said "V1 Power Seat Diode (Replaced by k24 as of by 1990 and also V5 Parking Brake/ASR/Electronic Accelerator (as of 1992 models 400/500E) However, on my 1994 E320 wagon, there are two relays on the ABS/ASR pump module, the 12 volt relay and the ABS pressure regulator.
I am tempted to get a new OVP relay brand mercedes or KAE Kaehler Overload Protection Relay (OVP). I need to do more research/studying on how test the OVP using DVM and other issues as well. Comments, feedback, advice is greatly appreciated it. Stay tune.