2003 Ford F250 SuperDuty 5.4 Fuel Pump Relay

Hey fellas- had a strange one come into the shop today. F250 Super duty 5.4L truck. Customer complains that it runs fine most of the time then cuts out and stalls. Most times it starts right back up. Put fuel pressure gauge and fuel pressure was normal. Decided to test power at the fuel pump at the same time and ran the truck for hours. Finally after about 3 hours of running is started to stall. Voltage at the fuel pump dropped and the fuel pressure dropped and truck shut off. Long story short, the truck finally quit and now will not run. Traced power back to the inertia switch, then back to the Central control board. I am looking for the fuel pump relay but can't find it in this truck. Verified the wire supplying power to the inertia switch is going directly to the Central control board. Can get the truck to run by putting power to the inertial switch wire at the Central control board. Is the relay in the control board?? Has anyone else run into this?

Pretty sure the fuel pump relay is integral to the Central Junction Box on those trucks. :lol: Brilliant design, eh?

That said, I've only seen one relay issue on these trucks, and that was due to water intrusion. I've seen more cases of PCM Power Relay issues, developing high resistance across the load contacts. That relay isn't part of the CJB, and powers the fuel pump relay (among other things).

Next time you get it to not start, check for power on F2.22 (20A) in the CJB. That fuse feeds the PCM, injectors and MAF. You could check for power at those places, but I figure F2.22 will be easier since you're already there. :silly: No power at the inertia switch but power on F2.22 means a genuine fuel pump relay problem. No power at F2.22 puts you towards the power relay.

Checked power at F2.22 and had power there. Customer opted for me to install a bypass relay. So...…. I installed a ground controlled relay controlled by the PCM( as with the OEM design) with a 20amp inline fuse and got the truck repaired. The only question that I had.... I called the Ford dealer for help and he told me the relay was behind the radio on this model. I had looked behind the radio before I did this repair and didn't see anything. Thanks for the help Tyler. I felt better doing this repair per your input.

I like it! I'm sure this truck has seen a few miles, so it's probably better off with the repair you did.

Behind the radio? The diagram was pretty clear it was in the CJB. I'll ask the Ford guy at work on Wednesday.