What should the resistance and current consumption of a 2004 Crown Victoria fuel pump be?

[brianl703]

My 2004 Crown Victoria has been sitting for a while and won't start.

It's not getting fuel, as verified with a scantool that shows the fuel pressure at 0.2PSI. It has a returnless fuel system.

I have voltage and communication with the Fuel Pump Driver Module because if I try to start it with that disconnected, I immediately get a code P1233 which means that the fuel pump driver module is disabled or offline.

I get no such code when it's plugged in.

I checked the resistance to the fuel pump and I'm getting 1.6 ohms.

I then tried powering the fuel pump with my bench power supply (current limited to 10 amps) and it drops the output voltage all the way to about 7 volts, meaning that at 12V this fuel pump would be taking more than 10 amps so it lowered the voltage to maintain it's 10 amp limit.

The fuel pump fuse in this car is 20 amps.

I checked the fuel pressure while I was powering the fuel pump from my power supply and it went up from 0.2PSI to 0.3PSI. I also did not hear it running.

Does it sound like the fuel pump is bad? Perhaps seized up or has shorted windings?

 

[Cujet]

Many 4 cylinder turbo fuel pumps draw 3A to 5A and some a touch more. I don't know what the Crown Vic pump draws but it's only 200 and change HP, so huge pumps are not needed. I did use fuel injection fuel pumps with a high pressure output in my gas turbine experiments. It was never 10A.

 

[clinebarger]

Most factory PFI pumps @45 psi draw 6 amps or so.

Try smacking the tank while powering the pump.

 

[brianl703]

Many 4 cylinder turbo fuel pumps draw 3A to 5A and some a touch more. I don't know what the Crown Vic pump draws but it's only 200 and change HP, so huge pumps are not needed. I did use fuel injection fuel pumps with a high pressure output in my gas turbine experiments. It was never 10A.

Yes, I am coming to the conclusion that this pump is done. Read elsewhere that the F150's fuel pump draws 7 amps.

I saw a YT video where someone used 14AWG bare solid copper wire to make jumpers to bypass the FPDM, and the car still didn't start AND they got 8V when they measured across the jumpers, so their fuel pump was also pulling excessive current probably due to it being locked up.

 

[brianl703]

Try smacking the tank while powering the pump.

I could, but even if that gets it going again I would never want to drive it anywhere without replacing the pump, since it will probably just crap out again and with my luck it'll be late at night miles from home.

 

[clinebarger]

More for diagnostic purposes.....Then you know for sure the pump was seized.

 

[chemman]

Delphi's amp draw spec for a replacement fuel pump for your MGM is 6 amps for average current flow. They do not provide a resistance value for the motor.

 

[Lubener]

Yes, I am coming to the conclusion that this pump is done. Read elsewhere that the F150's fuel pump draws 7 amps.

I saw a YT video where someone used 14AWG bare solid copper wire to make jumpers to bypass the FPDM, and the car still didn't start AND they got 8V when they measured across the jumpers, so their fuel pump was also pulling excessive current probably due to it being locked up.

Presently working on a bad pump on my 2003 GM which the pump winding has opened up.. My manual is vague regarding pump winding resistance. It states 10 ohms or less is acceptable which doesn't tell you much in the case of shorts. You are going to have to disconnect the two harnesses at the pump anyway (which is a PITA), then I would make sure you have no damaged wiring between the FPDM and the pump by rechecking to make sure the power line is not shorted to ground. The way the harnesses are routed above the tank, it very possible wiring could be pinched, damaged or shorted. Verify before getting a new pump.

 

[brianl703]

The way the harnesses are routed above the tank, it very possible wiring could be pinched, damaged or shorted. Verify before getting a new pump.

I checked, saw no damage under there. Also my power supply was not connected to vehicle chassis ground, but directly to the two wires going to the pump from the FPDM. As a side note, one of the terminal sizes used on aircraft (1.6mm round I think) is a perfect fit for the FPDM connector, my dad had a box of jumper wires with various sizes of male and female terminals (he was an aircraft mechanic) and I found what I needed to easily make a connection in there.

Also, I noticed that the fuel pump was pulling enough current to noticeably DIM the dome light when I turned the key to the ON position. (The dome light dimmed for a couple of seconds, which I think is how long the ECM turns the fuel pump on when you turn the key on but without going all the way to start). And that was with a 25 amp battery charger connected to the battery...

Pretty sure the fuel pump is DONE so I ordered another one. Ordered the whole thing, sender, bracket, and pump. Not going to mess with just replacing the pump to save $60. With my luck, the sender would crap out next.

Just strange that it failed by locking up and drawing excessive current instead of going open.

Noticed that the fuel tank is metal, can't wait to find out how much rust is in it. Might need to replace that too.

 

[brianl703]

Also I know that the fuel pump wiring in this car is on the same inline connector as the fuel tank pressure sensor wiring. And the fuel tank pressure sensor can be difficult to disconnect. Whomever replaced the fuel pump on this car the last time it was done (it has about 265K on it), just cut the wires and spliced them. Using regular butt splices that then corroded causing the check engine light to come on. I respliced them with heat-shrink tubing.

There's another way to do it. Here you have two connectors, left is the 3 position pressure sensor, right is the 8 position connector that goes to the harness to the rest of the car:

What you do is, on the 8 position connector on the new fuel pump assembly, make a note of how the 3 wires going to the pressure sensor are arranged, then pull that red piece of plastic out of the 8 position connector with needle-nose pliers.

Then, for each of those 3 wires, use a pick or jeweler's screwdriver to lift that wire's locking tang towards the center of the 8 position connector and pull it out of the back of the 8 position connector, it'll slide right out of the rubber seal.

Do this for the old fuel pump assembly too.

Then when you install the new fuel pump assembly, insert the wires/terminals from the pressure sensor in the correct order on the 8 position connector, then re-install the red plastic piece, just push it back in.

No need to disconnect the fuel pressure sensor connector and no need to cut or splice wires either!

 

[Lubener]

Sounds like you have a mechanical lockup failure of your pump. That will draw some current.

I used a long shafted small flat blade screw driver to release the pressure sensor connector. Took a few minutes. Not a problem for me to disconnect the pump wires either. I can then take the entire assembly to my bench to transfer the new pump onto the assembly and reinstall in the tank..

The fuel sender is very reliable and I trust the original more than an aftermarket Chinese made one. So I just replace the pump.