May I ask what the fuel pressure should be at fuel rail with KOEO? Please advise.

 

1997 and earlier Rangers, or Mazda B-series, uses a Return fuel system with fuel pressure regulator on the engine, they run 35psi pressure at the engine
1998 and up use Returnless, with fuel pressure regulator in the gas tank, they run 55psi at the engine

In a 1994 running pressure is 30-35psi
When engine is shut off the fuel pumps check valve and the fuel pressure regulator should hold pressure above 15psi...............for MONTHS and MONTHS

When you turn key on again the fuel pump will run for 2 seconds, and 2 seconds only, that will add 10psi to current pressure for start up
You can cycle the key on and off a few times to rebuild lost pressure, you get that 2 second run time EACH TIME key is turned from OFF to ON, so 3 times should get 30psi at the engine end of fuel system

Cranking engine over doesn't turn on fuel pump
When computer sees RPMs above 400 it will turn on fuel pump full time, its a safety thing
Cranking speed is 200rpms

 

Thanks RonD.
I am getting 37 PSI (KOEO) after cycling the key on and off for 3 times. Then, it drops 7 PSI gradually after few minutes and stays around 30 PSI for a while (I am sure it will drop slowly as time goes on). That explains why I had problem starting the car first time in the morning. Now, I have to cycle the key 3 times and it starts right up. Where is the leak? Please advise.

 

You can take off the fuel line that's on the Fuel Pressure Regulator(FPR), its the Return fuel line that runs back to the gas tank

Put a towel down under it to catch any leaking fuel
Cycle key on and off two times, that should be about 20psi, FPR is rated for 42-45psi, engine off
Watch to see if FPR keeps leaking fuel out, if so thats where you are losing the pressure, replace FPR

If no fuel is leaking out then the Check Valve inside the fuel pump is bad, its not a separate part, its inside the fuel pump
Its is possible that the fuel line inside the gas tank is leaking, so no gasoline smell or visible leak outside, but still need to access gas tank so............


On the 2.3l the lower intake and fuel lines seen here: https://www.mazdabg.com/ftp-uploads/.../85553093L.gif

Its the Fuel Return line you want to disconnect, NOT the fuel supply line
The larger cylinder is the FPR and has a vacuum hose nipple on the top

Google: ford fuel line tool
There are videos that show how to remove Ford fuel line, but if you have changed a fuel filter then you already know how, lol, you just don't have to lay on your back while doing this one

 

Thanks RonD again.

I actually replaced FPR two years ago to troubleshoot something else. I also replaced the original fuel pump 3 years ago with a cheap aftermarket one (I suspect the check valve is no good as well). For now, I am just going to cycle the key on and off 3 times and start the car which sits for long time. I don't think it hurts anything by cycling the key ... Correct?

 

Correct, it doesn't hurt a thing