Gas gauge is not working now already checked the fuses there good where to now?

 

...if all was working,then not I'd suspect the tank sending unit assembly.

 

I guess that means dropping the gas tank

 

Don't know what model or year vehicle you have, but with the older years you could ground the wire from the sending unit to the gauge and it usually went to the full mark on the gauge. That confirmed the gauge in the dash was OK. If you were able to do that at the tank and received the same result , it confirmed the wiring was OK.Then you went to the tank sending unit. It usually makes good sense to be as sure as possible before getting involved in a bigger job like dropping the tank especially if it is full of fuel. And they can be pretty heavy to handle when full of fuel.
Sometimes the float will come off the rod for the gauge and the rod will go to the bottom of the tank and give an accurate reading of empty.

 

...yep,usually.I don't know what year/model truck you've got.Dual tanks?Check the obvious first..could be a bad connection at the tank sending unit,but I've found that either the tank float can sink as a result of a pinhole (metal soldered floats),or the rheostatic sender can wear out.Vibration is the killer...

 

Thanks Gary and hanky...by the way its a 1988 ford f350 econoline motorhome

 

Is that an 88 E350 or F350 ? I was always under the impression that an Econoline was the E series. There are some differences between the E and F models, but not in the case of the fuel gauge.

 

Ok looked at top of gas tank and it looks like a brand new sending unit has been put in gas tank it's still shiny I finally got to where I can get my hand to the back of the gas gauge in dash and it has to little studs on the back but it's nothing hooked to them and I wonder why its not working...lol but I cannot find any wires back there that looks like it hooks to the gauge...could I tap into the wires coming from the tank and run two wires of my own to the gauge? 1988 ford f350 econoline with a 460 in it

 

Hanky is right...drop the tank as a last resort,especially now that you suspect the tank unit is OK.

 

I would be a little cautious regarding the tank sending unit. If you didn't install yourself and were sure nothing was bent or jammed on installation , the sending unit could still be a problem. Just because it appears new doesn't mean it's working properly.
The gauge assy in the dash may be connecting to a printed circuit board behind the dash itself. The hardest thing is to remove the speedo cable from the inst panel. Then you could be sure of what you see. As long as the dash is apart and the tank is down far enough , that is the best time to access both gauge and sending unit and check the units. I still would remove the tank unit and be sure everything is working properly since you have gone this far.