No fuel for the Ranger

2004 Ranger 4.0 V6 stock. I have no pressure on the fuel rail. The fuel pump motor does not whir and is not accessible except by dropping the tank, which is nearly half full with nothing here to put the gas in. I checked the voltage at the inertia sensor and am getting 6volts when measured with key already on. If I setup to measure with key off, the voltage starts at 11v and drops to 6 over just a couple of seconds. What is the voltage supposed to be? I jumped the switch (harness side) without any change. I changed out the relay with various other ones and it offered no improvement. Engine turns over and over but will not start. The fuel pump fuse is also good. Truck was running fine when I parked it. No issues whatsoever. Two days later, I go out to start it and I get what I've explained here. I haven't measured the voltage at the relay sockets, but I wouldn't know what I was getting as I don't have a diagram or reference for it.

princeb said:

2004 Ranger 4.0 V6 stock. I have no pressure on the fuel rail. The fuel pump motor does not whir and is not accessible except by dropping the tank, which is nearly half full with nothing here to put the gas in. I checked the voltage at the inertia sensor and am getting 6volts when measured with key already on. If I setup to measure with key off, the voltage starts at 11v and drops to 6 over just a couple of seconds. What is the voltage supposed to be? I jumped the switch (harness side) without any change. I changed out the relay with various other ones and it offered no improvement. Engine turns over and over but will not start. The fuel pump fuse is also good. Truck was running fine when I parked it. No issues whatsoever. Two days later, I go out to start it and I get what I've explained here. I haven't measured the voltage at the relay sockets, but I wouldn't know what I was getting as I don't have a diagram or reference for it.

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The initial 11v dropping to 6 volts at key on is normal. The fuel pump "should" prime for 2 seconds then shut off until the engine starts.

Go back to the fuel pump connector and see if you still get these voltages there. If you do, the fuel pump is dead.

Instead of dropping the tank just take the bed off. Way easier.

Is the fuel pump relay clicking?

I can't get to the fuel pump connector. It's inaccessible unless I can teach my hands to see and compress a bit more. Only place I can see the connector at all is the cab/bed gap. Colintrax's idea is a good one that I've done before on another project (and forgot about), but I want to explore everything upstream before having to take the plunge downstream. As far as the relay clicking, the engine turning over drowns out every sound. Plus it develops a semi-violent shaking/rocking as it continues turning over. Is there some way to test the relay out of the truck? Is there a simple way to test the relay socket for correct voltage on each pin (and/or correct grounding, whichever the case may be)? I have a Fluke multimeter and probes. I used it on the inertia sensor harness.
Thanks for the help!

Is there a web page somewhere that details relay and socket troubleshooting and diagnosis? I know there are pay ones readily available, but being unemployed at present and the truck transportation to and from the work I do get makes those a bit beyond arms reach for the time.

Your test at the fuel pump inertia switch was good, and, in the middle of the circuit. If you have voltage at the inertia switch the relay is working, you need to head "downstream" now.

The remaining test is for power at the fuel pump connector to eliminate bad wiring. if the voltage is present at the fuel pump connector, the pump is toast.
Look for a retainer holding the wiring. Some are "looped" and once released will give you some slack.

I "think" the fuel pump wiring goes past the fuel pump then back forward.

So the same 6v at the inertia switch is what I should be getting at the fuel pump connector then?

princeb said:

So the same 6v at the inertia switch is what I should be getting at the fuel pump connector then?

Click to expand...

11V when you first switch on the key. You might need a helper to switch the key on and off for you.

The "priming" voltage is only present for 1-3 seconds when the key is first switched on. Then it drops to 6v until the engine starts. In your first post you mentioned you measured this voltage at the inertia switch.

I too suspect the fuel pump is bad. My 04 Ranger's
pump went out at only 61K miles, so I cut it apart
and examined the brushes. They were OK, but had
worn deep grooves into the commutator (or whatever
it's called?). After reading other posts, it seems Ford
installed a bunch of failure-prone pumps around the
04 model year. (The carbon brushes are too hard, or
either the copper commutators are too soft.)

To replace the pump, I simply loosened the 6 bed bolts,
disconnected the rear lights electrical plug, and levered
the bed up with a piece of 2x4. The use of 4x4 blocks to
support the bed side allowed plenty of room to access
the tank and pump.

Runnin'OnEmpty said:

To replace the pump, I simply loosened the 6 bed bolts,
disconnected the rear lights electrical plug, and levered
the bed up with a piece of 2x4. The use of 4x4 blocks to
support the bed side allowed plenty of room to access
the tank and pump.

Click to expand...

I want full access up top to check everything from above. I won't remove the bed, but slide it towards the rear of the frame 1/3 of its length (since I can already see the connector without moving it as it is). Should reveal enough without requiring full removal (2x4 sticks ready for rear section JIC). The bed bolts are marinating in penetrating oil to offer a little ease in removing them.

However, there is a question remaining. I have few choices in where to get the new pump. O'Reilly's, Advance Auto, and AutoZone. Which of the 3 should I stay away from? I've read in other places online that AutoZone is to be completely avoided, but my experiences with O'Reilly's has been across the board bad parts wise. But what of Advance (which has the pump assembly in stock)? And thanks for the info. My truck was bought used and has 165k+ miles on OE fuel pump. But being that I bought it from upstate Ohio, underbody rust was the major issue. Front end suspension and steering work straight out of the gate. Still came in under NADA guide cost even with the work. I just have a bone to pick with Ford about their pedal assemblies. :thumbdwn:

There are several pump brands to choose from.
I bought a Carter pump assembly for my Ranger,
because it was made in the USA. It was identical
to the Motorcraft that came stock in the truck. I
suspect that Motorcrafts are re-branded Carters.

Since then, I replaced an Explorer pump with a
Bosch. It's mfg in Germany and seems to be well
made.

Motorcraft, Carter, and Bosch pumps seem to be
the better ones. I'd stay away from the cheaper pumps
that are mfg in China.

Good luck with the install.

Runnin'OnEmpty said:

Motorcraft, Carter, and Bosch pumps seem to be
the better ones. I'd stay away from the cheaper pumps
that are mfg in China.

Good luck with the install.

Click to expand...

Thanks. I got it done, but will have to put the bed back together tomorrow. The pump was the issue, but for an obvious reason. At the connector at the motor itself within the assembly, the housing for the metal connectors had burned and disintegrated. Before I let the Advance Auto guy take it away, I took a pic of it for evidence because it is going to be something hard to believe for many. The gas tank was half full, and the connectors were powered. By all measures, the tank should have exploded. But it didn't. And I am blessed by Jesus. And I had to buy what Advance had, an Airtek or Airtex or something like it. I started the truck after I got it in, and it ran fine.

Back in 1996 a TWA Boeing 747 (Flight 800) exploded
over the Atlantic due to overheated fuel vapors ignited
by a spark in a tank.

Never understood how an electrical component like a
fuel pump could safely run submerged in gasoline.
Makes me yearn for the good ol' days of carburators and
mechanical fuel pumps.

Glad you got it running again.

https://www.facebook.com/photo.php?fbid=10204396220321133&set=pcb.10204396223721218&type=1&theater

Pic posted to my FB page (because you can't post pics directly here)

Thanks a million for everyone's help!