Fuel Pump Relay Gremlin

[C420sailor]

Hey guys, looking to bounce something off your 20lb Explorer fixing brains.

‘99 EB 5.0L. 125k hard miles, I’ve been nursing her back to health. Did a ton of work. She runs smooth as hell, idles like a Swiss watch.

Took her to dinner with no issues. Just so happens I was monitoring TFT with Forscan (to double check I installed my external filter right) and she popped a P0230 fuel pump circuit code. Trims looked great. Weird.

Got back in after dinner, turned key to on and the check engine light was flickering. No method to the madness. Tach needle was twitching too. Clicking from the engine that I couldn’t isolate, but the FP relay was also clicking away (truck not running).

I swapped the FP and horn relays and everything resolved. Truck took a little cranking to start, but ran great with fantastic trims the whole way home. No codes returned, including the 0230.

I’m thinking that relay was on the fritz and possibly not holding, but I’ve never seen the flickering check engine and bouncing tach before.

I’ll likely check idle fuel psi tomorrow anyway.

Thoughts?

 

[donalds]

I had this happen
Not as bad as yours tho
Go to the jy for a ford relay the aftermarket ones suck

 

[J_C]

Seems like just a rare event where you caught the relay misbehaving, right at the start of it, was continuing to work just enough to keep the engine running but misfiring which would account for the RPM changes and engine light. If swapping the relay hadn't worked then I would've wondered about an intermittent wiring fault or loose battery cable clamp, or of course bad fuel pump.

 

[C420sailor]

Drove it again today with a different relay. No issues, runs great. I couldn’t see it in the dark, but the relay I pulled out was an aftermarket one, probably Chinese junk

 

[C420sailor]

Confirmed. Was driving down the interstate and the horn started honking itself haha.