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Jim18655 · 09-23-2021, 06:17 PM

Burnt contacts in the fuel pump relay could also cause problems.

RealNiceTent · 09-24-2021, 02:40 PM

Jim, you are right about the burnt contacts causing a voltage drop, and could be the problem since it takes multiple key cycles to get 15lb pressure, and in a "throw parts at it" approach you would think that would be second part to throw at it. If Pandarevolt doesn't come back and post we'll never know, and his fix won't be here to help someone else in the future.

TeJay · 09-24-2021, 07:07 PM

Very easy to check. Most of the Ford relays are the same and can be swapped for one you know is working. Or just swap relays and see what happens.

THenne1713 · 09-24-2021, 07:36 PM

Quote:

Originally Posted by Pandarevolt

Hey y'all,

This is my first post here after a fair amount of reading through stuff. I've got a 2011 Ford E350 Super Duty with the 6.8L V10 gas engine, and I'm only getting 15 psi to the fuel rail. I've had 3 mechanics say it was the fuel pump, so I replaced that, and still getting the same results. We have also replaced the throttle body, TPS, and MAF sensor. I've been stuck in Richmond, VA, for 2 weeks now trying to figure this out, and I need to get back on the road ASAP. Any ideas?

Edit to include that there is no fuel pump inertia switch on this model, and that the fuel filter is on the pump itself (no in-line filter). I'm thinking it's a wire I can't find or that the line is just clogged somehow.

I am no expert, but pretty sure there is a FUEL RAIL PRESSURE RELIEF VALVE ($5.34 ROCKAUTODOTCOM) that is on the outlet end of the FUEL MANIFOLD that is normally closed, and opens to bleed pressure as engine slows down/ demand drops/ pressure rises/ and PR opens to return excess to the tank. (SOUNDS LIKE yours maybe stuck OPEN?) P.s: I also agree w/ replacing the RELAY ... ALWAYS w/ New PUMP
https://www.rockauto.com/en/catalog/...ef+valve,15150

Pandarevolt · 09-25-2021, 05:28 AM

Just checking back in to thank everyone for the replies. I gave up and sent it in to the pros at Colonial Ford in Richmond, but they are backed up for 3 weeks until they’ll be able to give it a look. Since I’m traveling (I’ve been on the road for almost a year now), I opted to fly home and come back for it once they’ve gotten a chance to diagnose the issue. I’ll be sure to update again once I know more.

avfordguy · 09-26-2021, 12:42 PM

FYI, 2011 e350 v10 has a fuel pump driver module, that is between the battery junction box and the fuel pump, it varies the voltage to the pump based on load commands from the pcm, normal fuel pressure for koeo is 55 to 60.