I want to disconnect the fuel filter and drain my gas tank since the flapper wont allow me to siphon it. The problem is, I need to know which fuse relay to short to keep the fuel pump running until the tank is dry. I have an '05. I looked in the manual and didn't see it. It's either in the main box in hte passenger or (hopefully) in the box under the hood. I need to know which number fuse to pull. Any help would be great.

 

wont just turning the key on work dont the fuelpump run till it gets to like 40psi

 

No. I attached a hose to the front of the filter and turned the ignition on. It did absolutely nothing. I need to know which fuse regulates the pump so I can short it out and keep the pump running. I'm at wits end with this. I REFUSE to pay a dealership hundreds to siphon a *******ing tank.

I really do not want to drop the tank myself as I have never done it before and there are 15 gallons of fuel in it. Someone please tell me what fuse number on an 05.

 

why are you doing this anyway

 

There is no relay to jump to force the fuel pump on. The pump is controlled by the PCM, that controls the fuel pump driver module. You go around, jumping relays, you've got a good chance of smoking the PCM and/or FPDM.

I'm wondering too, why the hell are you trying to drain the fuel tank? Get a bad batch of fuel or something?

 

if the fuelpump is bad it wont pump if you dont want to take the gas tank off with it full take the bed off or you may try taking the fillerneck off and see if the gas comes out

 

Couldn;t you just hook up a hose to the pressure test port on the fuel rail under the hood? As for making it run continuously, the dealership would do it by manually toggling the bit for the fuel pump relay in the PCM controls. It's not difficult, but you ned the proper diagnostic computer to enable it. (i.e. not cheap!!)

You might be able to just connect a hose to the port on the fuel rail. If the pressure drops from the drain, the pump may or may not cycle to maintain the pressure. I don't know.

You could also jumper the two connections on teh relay, bypassing it. Use heavy gauge wire and connect it across the proper two terminals and it should run until you yank the wire.

Good luck!

 

There is no fuel rail schrader valve on an '04+ F150.

 

Just checked the manual... to drain it, the manual says to disconnect it at the tank and stick a siphon hose in the tank. Should work just fine. It may be easier and flow a little faster if it's up on a hoist or at least stands/ramps when you do so.

I'm still curious: What's the point in draining it?

-Joe

 

I had one at work that had 3/4 of a tank of watery, murky fuel. I drained it by hooking an adapter inline of the fuel rail that had a schrader valve on it, hooking my fuel pressure gauge to that adapter, then running the engine while drawing fuel with my pressure gauge sample port. It took about an hour, but I drained it well below the low fuel warning, to about 15 miles to empty.

 

If you have a SCT tune a dealer or with the PRP software you can modify the duty pressure and make the pump constant (KOEO).