1989 F150 4x4 gas tank leaked (rear tank) had it replaced , ran out of gas today @ half tank register on gauge, also oil pressure gauge fluxauting from normal to o. Is it a bad ground, if so where is the ground for the gauges.

did you replace low pressure pump in tank, There is actually a low pressure pump in each tank and a high pressure pump inside the drivers side frame rail about right under where the driver sits.

You probably have a ground wire not making contact to ground on the front tank sending unit. OR the sending unit itself inside the tank is faulty. Either way, when a gas guage goes to full all the time (empty or full), this indicates that NO ground is available for the sending unit.

replace front fuel pump because gauge is made into fuel pump and not serviceable. Or poor boy way of getting by would be fill front tank with gas reset mileage drive normal for a day. refill again with gas note gallons used and mileage driven for average miles per gallon. front tank should be around 17 gallons multiply by mile per gallon you figured

You probably have a bad sending unit for the fuel level in the tank. this would cause the gauge to be erratic when the level is below 1/2 tank and the float is moving around much more than when full. The oil pressure gauge problem could be caused buy a loose wire connection or a faulty sending unit.

Well fuel gauge stuck temp oil pressure gage all gages i say you have one of the wires pinched above the gas tank!!!!good place to start

I would check the actual oil pressure with a wet gauge. Locate the sending unit on top of the oil filter housing, remove the sending unit and install the wet gauge to check the actual oil pressure.

The sender unit in the tank is the most likely cause. To test the panel unit, remove the wire from the fuel tank unit and gound it. The panel gauge needle should move up full scale to hot. Remove the wire from the ground and the gauge should return to empty. If this test is ok, the tank unit needs to be replaced.

Fuel sensor is not working well. Just changed mine today for the same problem.

You may have run out of gas in the front tank, but the gauge may have been reading the rear tank or the front sender is stuck. Is the fuel line switched electrically or manually controlled? How are the gauge connections switched?

HI, the oil pressure sending unit may be malfunctioning at this point. this will cause erratic readings. if your oil level is proper and there are no apparent oil leaks, you will need to replace the oil pressure sending unit. this will fix the erratic oil pressure readings.

Concerning the gas gauge. this device also has a sending unit that sends the correct fuel level reading to the gas gauge via wire transfer. this sending unit is located and attached to the fuel pump assembly inside the gas tank. replacing this device will fix this issue as well.

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