Hi all, new member here, decided to make an account and see if anyone could help me out!

Currently just replaced the fuel pump after the truck suddenly stopped running. What lead me to this was low fuel pressure ~ 30psi. After replacing the pump it still won’t stay running, if I cycle the key a few times it will run longer than before but dies out like it ran out of fuel. Checked the inertia switch and pushed it down but still the same issue. All of the fuel system has been replaced by myself aside from the regulator. But I did not see any rapid decent in pressure when testing fuel pressure so I figured it was still fine. Any info or diag ideas?

2003 Ford Ranger XLT 3.0 automatic trans

 

Welcome to the forum

You said Fuel Pressure was 30psi before the new pump, what is it now?

55-65psi is the expected pressure on 1998-2011 Rangers

Also 1998-2011 Fuel Pressure Regulator(FPR) is in the gas tank on the fuel pump assembly, did you replace the whole assembly or just the Pump?

2001-2011 have a 3 hose Fuel Filter, 2 hoses come from the gas tank, one is actually a Return hose that goes to the FPR in the tank

You found the inertia switch, if possible put a Grounded test light or volt meter on one of its terminals, doesn't matter which one
Light should be on, or 12volts seen after start up and stay that way
12v will be lost if RPMs drop below 400, i.e. engine stalls, that is normal
But should have 12volt all the time when engine is running

 

fuel pressure is ~ 60psi, I replaced the whole assembly for the fuel pump last night hand replaced the fuel filter a couple months ago. This morning I decided to swap in a brand new filter just to be sure. Truck is attempting to start better now. Even stays running if I add some throttle input. But still has a very rough idle and will die if I let it idle on its own. No codes either.

 

The truck now will run with the turn of the key but still idles poor and will die out if I don’t keep an eye on the rpms. Thinking about going through and checking everything that can mess with idle. Possibly take it on a test drive around the block.

 

Cold gasoline engine won't stay running without being Choked
In fuel injected engines this is done by the computer
Rich Mix and higher idle
On fuel injected engines the Idle can only be controlled by an Air Valve, like a mini throttle plate, it lets in more or less air to set a stable idle
Ford Calls theirs the IAC(idle air control) Valve

It looks like a can on it side on the throttle body, has a passage that by-passes the throttle plate
2 wire connector, Red wire has 12volts key on, the other wire goes to the computer, it controls the Valve's position by Pulsing the Ground, same as raising and lowering 12v voltage, but safer
IAC Valves rarely fail but are often replaced, lol
You can clean them, just remove and clean the air passages
While its off the engine, turn the key on
Plug in its 2 wire connector and you should see the valve inside move, then unplug it and it should move again, it has a spring that pushes it closed


Have you checked spark plug firing order?
Coil pack
3 4
2 6
1 5
front

The 5 6 4 side OFTEN gets miswired, so follow each of those wires to its spark plug

Ford V6 engine cylinders are numbered this way
3 6
2 5
1 4
front

People often assume coil pack would be wire the same, its not, follow the #5 wire on coil pack to the center cylinder on drivers side

 

coil pack, wires and plugs are all new and in the correct order, I’ve replaced those as well within the year. As for the IAC I did end up taking it off this morning and cleaning it out and verifying that it does still work. Put everything back together and took it for a drive. It drove just fine aside from a very rough idle at stops. Filled the tank up and brought it home. So far the idle is calm and where it should be, did spot some coolant coming out of the water pump after putting everything back together. I guess that’s a new thing to fix lol. In short I think after putting in the new fuel pump and priming the system it was IAC giving me trouble? Unsure but it is running fine now.