I have a 2003 F150 Screw 5.4 engine. About a year ago I was visiting family out of state and my truck died on our way back to NC. I was in denial about it being the fuel pump and looked for other excuses. One reason I thought it was not the pump was because I could hear it prime but there was no pressure. I changed the fuel pump anyways and it turns out that was the problem. I have since had spark plugs changed by Ford dealership with Motorcraft.

Now a couple weeks ago I go outside to go to work and the truck started for a fraction of a second and died. Now it will crank but will not start. I checked to see if I could hear the pump and I could but I remembered I could last time also. I checked for fuel pressure at the fuel rail and it showed 10PSI (obviously not enough). I had a warranty on the pump so I went ahead and changed it because I figured I was a pro at this point, but that was not the issue this time.

Fuses and relays are good, inertia switch is good, I replaced fuel pressure regulator and fuel filter, and the Theft light is NOT flashing. The pump is getting power but the engine is not getting enough fuel. Any help with diagnosing this issue would be much appreciated. Thanks.

 

I have a 2003 F150 Screw 5.4 engine. About a year ago I was visiting family out of state and my truck died on our way back to NC. I was in denial about it being the fuel pump and looked for other excuses. One reason I thought it was not the pump was because I could hear it prime but there was no pressure. I changed the fuel pump anyways and it turns out that was the problem. I have since had spark plugs changed by Ford dealership with Motorcraft.

Now a couple weeks ago I go outside to go to work and the truck started for a fraction of a second and died. Now it will crank but will not start. I checked to see if I could hear the pump and I could but I remembered I could last time also. I checked for fuel pressure at the fuel rail and it showed 10PSI (obviously not enough). I had a warranty on the pump so I went ahead and changed it because I figured I was a pro at this point, but that was not the issue this time.

Fuses and relays are good, inertia switch is good, I replaced fuel pressure regulator and fuel filter, and the Theft light is NOT flashing. The pump is getting power but the engine is not getting enough fuel. Any help with diagnosing this issue would be much appreciated. Thanks.

 

So while you're cranking the engine, what is the fuel pressure?

 

While cranking the engine the pressure reads 10 PSI.

 

You must have either a restriction in the fuel feed line (filter, rust, bend, kink, rot), not enough amperage to sufficiently drive the pump from corroded wiring, bad connections, burned relay, or the new fuel pump or filter you got is also bad.

I am of course assuming you have a full battery and sufficient fuel in the tank.

I can't think of anything else. Does it start with starting fluid? That may indicate your pressure gauge is bad. Can you bleed off the 10 PSI, then crank it again to validate you're not just reading residual fuel pressure?

 

What pump did you use? If it aint motor craft that could be the problem. Aftermarket pumps are junk.

 

Ok. This week I am going to check fuel pressure in the line leading out of the pump. If there is no pressure I am going to guess it is the pump again. It is not a motorcraft pump but I do have a warranty on it again. Thank you.

 

Yes and yes to battery and fuel (although I will need to charge the battery from multiple cranks now) I tried it with starting fluid and it didn't start but it backfired. I am guessing that means there is spark but could it have just been pressure? And as far as PSI I had my wife crank it and the gauge rose to 10. Then I had her turn the key to off and crank again and it rose from 10 to 20. Thanks for the tips!

 

OK, so you definitely have spark. Do you get any pops at all while cranking? I'd think at 20 PSI there should be something. If you turn the key on and off several times, does the fuel rail ever fully pressurize? 35-45 PSI

Have you traced the fuel lines from the tank to the fuel rail to look for damage?

 

The only fuel pressure test port is the one on the rail.

 

Not sure if the 2003 has a fuel pump driver module:

FPDM thread

 

It does not. The 04 NBS was the first F-series to use the FPDM.