I have a 98 ranger with the 4.0 was running fine then quit like it ran out of gas. Checked fuel pressure only had 30psi replaced fuel pump assembly and filter and still only get 30psi now what do i do?

 

Welcome to the forum

Get a different pressure gauge?

1998 and up should run 55-65psi fuel pressure, but engine would still start and run on 30psi, it would start stalling out under high fuel demand

And when is fuel pressure 30psi and for how long?
From 0psi each time you turn the key ON and then OFF you should see 10-15psi increase in pressure, and that pressure should HOLD for MONTHS, not minutes, hours, or days, MONTHS

So if you cycle the key on and off 5 times you should see 50+psi at the rail, and it should hold there
If pressure is dropping with key off then you have a leak in the system
If you do not smell gasoline then the leak is internal to the system

At the engine end there are the fuel injectors and Pulse Damper
If an injector is leaking then engine should start but run very poorly and put out a bit of black/grey smoke
Pulse Damper is located on the end of the fuel rail, it has a Vacuum hose attached
If diaphragm on Pulse Damper leaks, gasoline would be sucked into intake via that vacuum hose, engine would start but get flooded out so run poorly with black/blue smoke, like leaky injector
Remove Pulse damper vacuum hose and check it for gasoline

Fuel pump has a built in Check Valve, back flow preventer, when pump is off valve is closed so pressure between pump and injectors will HOLD, usually above 50psi, but above 40psi is fine

So if the 30psi drops to 0psi when key is off then there is a pressure leak

 

Thanks Ron,
sometimes it takes 5 or more cycles of the switch to get to 30 psi. Most times it reaches it by the third time Once it gets there it holds at 30. Then i can crank it over and it starts but just runs a few seconds and as the pressure drops the engine dies. It wont maintainpressure when engine starts Didnt find anything wrong with damper had same symptoms before changing pump

 

This may change things a little engine starts with first try of the key switch runs up to about 1500 rpms then after few seconds idle gets rough rpm drops and then dies if i try accelerator after it starys it will die immediately

 

Ok tried a different gauge pressure reaches 40psi but when key is shut off it slowly decreases. Didn't see any gas in vacuum line on damper so may have leaky injector

 

I would say you have low voltage, corroded wire or ??, at the fuel pump or fuel pump is faulty.

"New" used to mean "tested and it works"
New now means "you test it for us and we will replace it if it is faulty"

leaky injector or not you should still see 60psi pressure from fuel pump

Test voltage at inertia switch in cab, passenger side below glove box or behind kick panel

Should show 5-7volts key on, cycle key off and on and you should see it go to 12.5volts for 2 seconds, then back to 5-7v

The 5-7volts is from computer, it monitors if fuel pump is getting power, the 5-7v has no Amps, so can't run fuel pump