You can test for diesel leaks at home, and do not need to spend the time and money required to bring your vehicle to a local shop. By adding a basic detection dye to your fuel tank, you can perform a quick diagnostic test in order to decide if your vehicle will need further maintenance to repair a leak. You can purchase the detection dye from places like Surf-Prep, a dealer in Kentucky. The price of the dye ranges from $22-$96 and contains enough dye to treat 1,000 gallons of fuel.
Pour leak detection dye into the fuel tank of the vehicle that you're testing, adding one ounce of dye for every 10 gallons of diesel fuel.
Let the engine run for two to three minutes so that the dye will be distributed throughout the fuel system.
Turn off the engine.
Check for leaks in every area of the engine using a black light. If there is a leak, the detection dye will glow green or pink under the light (depending on the brand of dye used). If you do detect a leak, bring the vehicle to your local repair shop immediately. This is not something that you can fix yourself.