I have a 2005 ford f 550 with 6.0 diesel engine. The fuel indicator works a times and at times not inspite there is enought fuel in the dual tank to a point that it gives me low fuel warning. also there are aux switches below the audio system which when 4 is on, the rpm goes to 1200 rpm. With a hydralic system runed by a P.T.O. i need 1400rpm. can it be re-programmed.

if this is a diesel engine the problem will be that the injector return line is in the from tank and the tanks are not equalizing out. When running 2 tanks it is best to have a balance line between the bottoms of the tanks so that fuel can flow where it is required.

Most likely it is in the gas tank

Keep the fuel filters clean, drain water out of the fuel tank regularly and use an injector cleaner made for diesel not gasoline injectors

drain the old fuel out of the system an change all filters..it sounds like the fuel has baterical growth in to....i know that sounds strange but diesel fuel can actually feed some forms of baterica ...it looks like a white gel...an u will need to have the fuel tank completely cleaned...u need to use fuel stable before u park diesel cars an trucks for a period of time

if its not getting fuel to rail then its your fuel pump sorry

inside the fuel tank ,combined float /pump unit

The "MOST EFFECTIVE
" way is to REMOVE The FUEL TANK and DRAIN it By Tipping it over to Pour From FUEL INLET HOSE. Im Sure you Dont want to Here this as it Requires Much WORK . , BUT It IS The MOST EFFECTIVE Way to EMPTY The TANK.

Did you replace the glow plugs or intake heater? Very bad to use ether.

You can buy a suction hose small enought to get intothe tank at an auto parts store. you will have to remove the fuel from the tank. All of it and then replace fuel filter.

Dual tanks sound like the float in the tank is stuck. Need to make sure its not binding up. (I did alot of those jobs)