portert

Hey folks,

I have a 2002 F150 Supercrew. It has about 180,xxx miles on it. Lately I have been having an issue with the fuel pump not engaging when I turn the key. I have replaced the pump and the problem remains. It doesn't happen all the time, but most of the time. After cycling the key on and off a few times, I can hear the pump kick on and the truck runs fine. I have thought about the everything from the relays to the Anti-theft systems for failures, but the fact that it does work after a few tries (sometimes 1 try, sometimes 4-7 tries) has me confused. Any suggestions?

RCButler

Sounds like the relay in the power box under the hood is going bad. I've had several relays that acted in the same manner before failing all together.

Relay is about $15.

Jbrew

Wiring harness or grounds, something is shorting since you covered the relay. That's next. I can't recall if the pump has a direct ground or uses the PCM. Ford changed distribution many times for this gen. Get diagram for your model from a service DVD and begin chasing it down. I'd start at the connector for the pump. When it's acting up or just go through the harness wires and ground one by one. Check the fuses involved with the circuit, well not the fuses but the holders for any sign of arcing. There more than one involved and they aren't necessarily marked as a fuel pump fuse. Another circuit could cut the fuel pump...safety, anti theft or whatnot. Not much else you can do since you covered the easy stuff. Check the PCM signal as well. It's not common for the PCM to flake out like that, but like I said, you covered the easy stuff right ? New fuel filter as well ?

portert

Thanks guys....I'll check it out today. I wasn't aware that a relay could fail intermittently.

Jbrew

A little trick with relays, bad ones are always warm - hot. A good one never gets that way.

RCButler

I had a Ford starter relay in an '81 Sportster. Got about a 16 to 24 months use outta it before it would begin to fail.
It would start fine then it would take a bit longer, then longer again.....usually only in the morning or at first start after sitting 6-8 hours. When it began doing it at every start it was time to change it. Sometimes it would take 3-5 days, others 10-12 days before it failed from the beginning of it acting up.

portert

I've found that the relay seems to operate every time the key is turned. The fuel pump doesn't always engage though. I am able to feel the relay switch and the pump not turn on.

Jbrew

Did you replace the fuel strainer as well ? A lot of times it's not the fuel pump relay, it's the PCM power relay that gets flaky. You never did answer my filter question..any reason? The strainer or filter can kill a new pump quickly if neglected. And if that was the problem in the first place....

Raybz

Just because the relay is switching doesn't mean that the contacts inside it are conducting. Relays can pit and cause a high resistance connection. Try swapping the pump relay with a different one (like the horn relay) and see if that helps

Jbrew

I don't think you can with that model. I was going to suggest it, but that relay is like PCM relay...different. Worth a look though.