I found out that my pumps weren't getting 50 psi under wot so I dropped the tank. I'm running dual 255's and they were installed at the engine shop. I found out that one of the clamps on the "Y" above the pumps was too far down and had crushed the end of the plastic "Y" so one pump couldn't pump any fuel. So I replaced the "Y" and reassembled things. Now I have 50-52 psi with just the key on and about 30 psi when running. Problem is that as soon as I start to drive the truck the pressure starts dropping way down, to near 20 psi moving up and down 4-5 psi constantly. Well of course the truck doesn't run this way. I had totally steady fuel pressure before dropping the tank, just was missing the extra psi under wot. Now I can't get any steady pressure except when I first fire it; as soon as I go to drive before I can even get out of the driveway it goes nuts.

I dropped the tank again and pulled everything out; no loose or cracked hose, everythings hooked up exactly as I first found it. I also bench tested both pumps and they appear to be fine.

Is there some weird ground cable on the top of the tank that was attached to the pump covers that I can't see? Any ideas what is happening to my pressure?

Jody


__________________

 

My guess is I have a bad pump. Coincidence that it quit after I pulled everything out, but nothing else seems wrong. I read where they say to jump the two fuel pump relays and compare pressure, but on my 03 there's only one relay and it runs both pumps at once. The computer drops the voltage down at idle cruise areas and then goes to full voltage at a preset maf or load and that's how the fuel pressure rises. Mine makes 47-48 psi with the key on, no running. Start it up and it's right at 30 psi, but as soon as I start to drive it drops to 20 psi, jumping around at that point.

I ordered two new pumps which will be here tomorrow. Good thing is I can now R&R the tank and pumps in about 45 minutes to an hour.

Jody