jakeq19

My 1987 F-250 has dual tanks. The front reads full almost all the time but will drop briefly and then return to full. The rear tank reads full until about 1/2 tank and then drops to the proper reading and bounces up and down from full. Here is the real wierd part, If I switch from the empty rear tank to the front full tank the truck dies like it is out of fuel. As long as I switch with fuel in the rear tank it will draw from the front. Any Ideas what the problem is?????????

89F150

I have seen this as a common problem, If i remember rightly when the fuel guage is pegged to the full all the time it is a switch problem, so check the switch
As for pulling the fuel out of the front tank, i think it was the sending unit

351w

well from what you described i hate to be the bearer of bad news but i have never heard of things happening like you described.
when you switch from an empty tank to one with fuel in and the engine dies it has to be a problem with the fuel tank selector valve which is located about half way back the driver side frame rail.
from the description i would almost garantee the rear tank needs a sender switch which is a common problem and will probably set you back around $100 if you do it yourself.
a sender switch will only send a signal to the gauge to indicate the fuel level and in no way affects whether or not gas will flow from the tank that is affected by the selector switch and selector valve.
the front tank i am not sure about and that one could be as simple as a rusted ground lead on the sender or that sender needs to be replaced as well.
the bummer is that you have to drop tanks to find out either way.
i suggest if you do it yourself just drop one at a time and you can still run off of the other tank.
hope this helps some and let us know how you make out.

89F150

Might just be me but ive read and heard on other forum sites of many people who have had this or similar problems. Who knows i might just be reading threads over and over again.
But anyway hope ya get the problem fixed.