fuel issues

[shaun89]

i grounded out my autometer gauge gauge and fried it (i think) but either way it doesnt work. so ive been using the trip-o-meter,and my gears arent correct, i should get 210 out of a tank (7mpg) but i ran out around 188 miles, which makes sense. but the past month or more my truck seems to be losing mileage real bad.i ran out at 138 miles and now i ran out at 116 miles. but i think the problem is in the tank now. i just ran out of gas warming my truck up a bit in my driveway (its level) and i could only put in about 18 gallons...i have a 31 gallon tank,so do u think my pick up could be floating around or something?

 

[Thunder]

If its TBI. The hose that comes off the pump in the tank may be cracked or split. That will cause you to run out of gas aprox at 1/2 a tank. either that or the pump is going out.
Either way. You have to pull the tank.
How long has it been since you replaced the fuel filter?

 

[shaun89]

o sorry, i forgot to add, i switched over to carb, and it also has a mechanical fuel pump. and i replaced the fuel filter about 8 months ago. the thing that is really confusing me is the fact that i could only put in about 18 gallons after it ran out,when i should be able to put in 30 gallons or so...o ya, i also used to hear when it was about 1/8 tank left or so,something getting thrown around in the tank. but since my truck is "running out" of gas early now, i dont hear that noise which makes me believe that its not low at all and the pick up is floating around in there or something. could it be that the pick up broke about half way down or so and its only getting gas from full to about 1/2 tank?

 

[Thunder]

When you switched over to carb did you remove the old fuel pump and replace with an older type sender and fuel pick up? If you still have the stock pump in there you still may have a broken or split/broken hose. If so. Once you get down to around 1/2 tank you will just suck air.
If you still have the TBI type tank. the Thing you heard banging around was prolly the baffle. They have a tendency to break free and float around. They usually only cause problems if you are below 1/4 tank

 

[shaun89]

i actually took out the stock sending unit and put in a new one but from an older truck that would be carbed. i believe i put one in from an 82-85? i stayed away from the 70s incase the tanks were different and stayed below the TBI years....i think my only option is to drop the tank and see whats inside....thanks for all the help though!

 

[Thunder]

Before you drop the tank. Check the fuel lines and connections for air leaks between the tank and the pump. Maybe something broke, got loose, or something.

 

[shaun89]

ok,will do! thanks