How to Pressure Test a Gas Tank

by Alissa Jordan
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pressure guage image by Jeff Davies from

Fuel problems can be difficult to diagnose without paying the host costs of a repair shop. Pressure testing is an excellent, inexpensive way to troubleshoot problems with gas tanks and fuel pump systems. By pressure testing, you can rule out certain conditions, such as a leak in the tank or a plugged outlet. This quick method demonstrates pressure testing while the tank is still inside the car, reducing labor costs.

Step 1

Locate the supply and return lines running out of the tank reservoir. Clamp the supply line tightly with a pair of needle nose vise grips. Clamp return line tightly with a pair needle nose vice grips.

Step 2

Find the overflow house next to the fill spout and clamp with the remaining pair of needle nose vise grips.

Step 3

Place a rubber grommet of correct size into fill spout, pushing hard to ensure a complete seal. Pump pressure tester up to 10 pounds per square inch (psi). Do not exceed 12 psi. Let it stand for five minutes.

Check the pressure tester gauge for the psi readout. If the pressure has dropped from the original reading, there is a leak. If pressure has held, the tank is leak-free.

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