Well it still does it and the check engine light came right back on when I drove it afterwards so im sure there are codes back in there...

 

I ran them again and got 565 again and then under repeating codes I got 172 four times.

 

O2 lean code.

 

How many o2 sensors do these trucks have?

 

1, it reads both banks. All the spark plugs looked the same?

 

That's odd, you say it drinks gas but you got a lean code which means you aren't getting enough gas. Were both pumps changed? Because there is a valve in each tank that prevents fuel from being returned to the wrong tank. If the valve is bad then the fuel will be pumped to the wrong tank giving the illusion of you using more gas than you are. The valve comes with the fuel pump assembly.

As far as the running problem, you should check the fuel pressure yourself. You may have a bad fuel pressure regulator. I would also check the TPS for proper adjustment and check the MAP sensor for vacuum leaks.

Does the gas gauge still work with the other tank? If it does then a wire shorted out in the harness before the tank selecter switch, if it doesn't and it used to work then they fried your gauge.

 

Yes the other tank gauge still works, but is there no fuses or anything that could have been fried in the electrical or would it be a wire shorted out?

Also, only the front pump was changed. I am going to replace the o2 sensor first just because its the original and the truck has 153000 miles so I think its time. Hopefully that fixes the problem but I will also check the fuel preasure, but how would you check for proper adjustment of the throtle position sensor?

 

twin tank trucks have one relay for both pumps. I didn't read close enough to see its a twin tanker. One relay, two pumps. If the check valve is bad, it will bleed pressure off into the other tank over time.

That said, you say the truck runs rich. If the O2 stops working properly, the truck will add fuel in an attempt to satisfy the computer that isn't really getting a good reading. I think the sensor is only $50 or $60 tops.

As far as the shop hacking the harness? I'd make them fix every thing that died under their stewardship.

You pin the wires to check current while someone operates the throttle. You'll need a multimeter. I think OEM is between .97 and 1.01 at all throttle positions. I could be off by a tenth or hundredth.

 

im also new to the truck but i do have a 1996 ford taurus SHO, with the exact same problems to the t, rough idle feels like it will die, drive it hard but it doesnt kick in until 5 seconds after you mash the gas and the check engine light blinks, but my problem is cylinder 1 fuel injector, im not quite sure what the 5.0 has if they have any fuel injectors( i told you im new with this,not the SHO) dont know if this helps anyone out

 

The TPS should be at .97 to 1.01 at the idle stop, and increase gradually and smoothly as the throttle is opened.

Here's how the gas gauge works: The gauge gets power from the instrument panel and the needle moves with the amount of ground it receives from the sending unit wire. I don't remember if ground reads full or empty and if no ground reads full or empty but thats how it works, one will be full and one will be empty. You can test the wire by cutting it or unplugging it from the tank and with that tank selected and the key on leaving it unhooked to see if it goes all the way full or all the way empty. Then ground the wire and it should go all the way in the opposite direction. If the gauge does this with this test then the wire is fine.