Been a long time since I owned a Ford, and a lot has changed between a 70 Mustang and a 98 Ranger! I am having problems with this truck and not sure if I'm on the right path. It is a 98 Ranger XLT with 3.0 and is 4x4. It has been showing me the codes po171 and 174 together for a week or so and yesterday it showed a po1121 code. Today it wouldn't start? Tried starting fluid and it started, then died but then restarted and ran till warm. But it would not restart after?? I have been through the vacuum system no leaks found, and the IAC valve when un-plugged the idle drops the approx. 500rpm. I tested fuel pressure, key on (not running) 48psi but it would not reload pressure when relieved but it needs input from other things to do that. I have changed the fuel filter and had just put a can of sea foam cleaner into the tank. Also I replaced the PCM (brain), MAF sensor, cleaned IAC and checked gasket, even tried "cheating" with ether to find vacuum leak ( I know I'm old lol).. nothing. Suspect I have a bad pump but? Any ideas would help. Tkx

 

Welcome to the forum

Yes, 1998/99 Rangers were the first years to get the TRUE Returnless fuel system, and it did have issues

On the fuel pump assembly in the tank is the fuel pump AND the FPR(fuel pressure regulator) and its linked like this

Fuel pump----FPR------Top of tank-----------------fuel filter-------------------------Engine fuel system(rail)

So pump feeds the FPR directly, then OUT to engine
This setup had issues with pressure jumping around too much

In 2000 Ford changed it to a semi-Return system, and used a 3 port fuel filter
The pump sends fuel out directly to the filter, by passing FPR
The 3rd port on the filter is the RETURN line that comes back to the tank and to the FPR inside
This made for a more stable fuel pressure at the engine

Not that this is matters to you, lol

Yes, replace the fuel pump assembly, lifting up or off the bed is the best way to do this
Running pressure should be 60psi, so the 48psi is a sign there is an issue in the tank system, could be pump or FPR but both will be new with another assembly
You could try replacing Fuel filter FIRST, and see what pressure does, but I would replace filter regardless when you put in a new assembly

Since there is no fuel pressure sensor on Rangers the lower pressure would cause Lean codes because computer calculates the air/fuel mix based on 60psi, at 48psi less fuel is flowing out of each injector so Calculated mix would be "lean"

Lean or Rich codes don't mean the engine is actually running lean or rich, these codes mean the computer's original calculations were lean or rich, computer then corrects the mix based on O2 sensor feedback which takes maybe 2 seconds
The codes are to let driver know there is an error in the calculations, so an issue to be looked at

Vacuum leaks cause lean codes because UNREPORTED air is coming in that the computer didn't/couldn't include in its calculations for air/fuel mix

 

After a day of scratching my head, I( go out to truck, cycle key 5 times and it starts??? let it run, come to normal temp, then turn it off and... it won't restart no matter how I try???

 

Thanks for the confimation I figured it as much but didn't want to have to do it!!! lol

 

You can HEAR the fuel pump run for 2 seconds each time key is cycled on, its not quiet
Try it when you know its working, a click and then a HUMMMM from behind cab
Then listen when its not starting

You can try swapping Fuel Pump relay with another relay in the engine fuse box, NOT the PCM relay
And you can try a new fuel filter

 

Thank you all for the inputs, the truck is running fine still with the check engine light on for the same codes. I believe it to be a sensor / IAC valve problem more than the fuel pump. Pump should have died by now!? Will be getting a new motorcraft IAC and installing it soon so... we'll see, Thanks again