My seedomoter dosn't go above 45 and about this time the gas gauge is off about 1/4 tank--showing more than what's in the tank. Can you help??????

If you cannot fill the tank because of an erroneous reading then it is time to replace the gas gauge sending unit responsible for the anomaly. Hope fully you can do it from the trunk - otherwise you will have to drop the gas tank to gain access.

Okay, this is different. For one thing, the fuel cap will not show pressure. It is a negative Vacuum system incorporated with the Evaporator Emissions system. You check fuel pressure at the test port on the fuel rail.

What can happen is the plastic fuel strainer in the tank can dissolve into bits. These floating bits can redistribute and clog the fuel pick-up.

Second, at a point in time, gas station filters were a collection of tiny plastic beads. When the sack containing them ruptures, the beads are pumped into customers fuel tanks.

Anyway, it sounds like you have an intermittent fuel blockage. You might try changing the inline fuel filter and pump some fuel for a sample.

CHECK GROUND WIRE @ TANK/PUMP/SENDER ! #1 PROBLEM W/ SENDER/GAUGE ISSUE ! SENDER IS A OHM METER, IT CAN BE MEASURED . 0=EMPTY TANK,, 45=1/2 TANK,, 90 OHMS =FULL TANK, UNDERSTAND ?

Could be either one.
You could disconnect the harness at the tank and ground the gauge circuit to see if the gauge will go to full. If it does chances are the problem is the sending unit in the tank.

theres two plugs on the fuel pump. one is for pump and one is for gauge if you take pump out of tank and put a volt meter on the two outer prongs in plug then the two inner two of them will read the same when yoou move the level up and down and when you put meter on other two it will change when you move level or the level part of pump isnt working correctly. my old tahoe did that and when it would get to a 1/4 of a tank i knew it was almost out of gas.

Remove the fuel tank and change sending unit

i would say its the gauge sender,but the problem is its inside the fuel tank,so it looks like a job for the garage.adrian,,,,,,

most of the time this is simply just the float in the gas tank getting stuck had the same problem in my car. unfortunately you have to access the gas tank to fix, but it is an easy fix. hope this helps any questions let me know.

the problem is caused by a defective gas gauge sending unit, this part is located inside the gas tank, you must remove the gas tank to replace it.

there is a short in the wire going from the gauge to the tank. ck the wiring under the truck from the tank going forward, and ck if anything looks like its rubbing on the wiring harness.