gibblegeibel

i have 1989 ford f150. when i run the front fuel tank, it will run fine for about 30 minutes or so. the back tank will run good. both tanks have been replaced, both sending units and pumps and even the one on the fuel rail. the dual function resevior has benn replaced as well. have you guys had this problem before? what do you guys think.

VickMacky

What problem? You didn't say what the problem was. What's it doing besides "running fine for 30 minutes"?

gibblegeibel

when i run the truck on rear tank it runs just fine.

but when i run the truck on the front tank the truck doesn't run long. i notice when running the truck on the front tank when it starts to act like it is out of gas, and i hear a thumping and clicking noise from the motor also.but i can switch it over to the rear and run just fine.

so my question is what could be causing the truck to do this only when i run on the front tank.

Just call me Sean

iTrader: (1)

Tank switch may be dirty, which wouldn't allow full voltage to the pump. Very likely if you've been running the rear tank and recently fixed the front.

gibblegeibel

the tank switch is changed out for a new one also. the sending unit is getting full 12 volts to it

sambothehut

I recently purchased an 88 150 and had the opposite situation. Ran fine on front tank and ran poorly and would die on rear tank. Make sure both in tank pumps are working. You can open the fuel cap and hear them or from under the truck use a long screwdriver and hold it to the tank and put your ear on the handle. My gage worked on whichever tank I selected but the booster pump on the rail was pulling gas out of the front tank without the front in tank pump running. I had to buy a new OEM fuel selector valve to stop this from happening. Also if you run it and the fuel level in the tank not selected drops that another indication that the booster pump is sucking fuel out of the tank you are not switched on.

gibblegeibel

no i have noticed the fuel level higher than what it actually so post to be. so if i can load the vidoes i took i will show you guys what i mean.

gibblegeibel

ok i just checked the truck i didn't hear the front pump running like sambothehut said to, i found i could not hear the pump running. also when i turn the truck on with the rear tank selected i could hear the inline pump and the rear tank pump turn on. but when i have the front tank selected i only hear the inline pump running so i have come to the conclusion i need a new fuel pump for the front tank.

TaYlOrSK

I have the exact same problem with my 89. A mechanic buddy of mine told me that the problem isn't rare by any means and anything fuel related has to be replaced all at once. I'm not sure how true that is by my secondary tank works fine, although it takes $40 to fill it up and is gone in 3 days.