FITS: Fits for GM 6.6L Duramax engines for Diesel fuel pressure and vacuum testing
3-1/2" gauge reads 30 inHg to 15 PSI
The pressure gauge reading of the fuel pressure tester may be zero, low, or high. Zero pressure means the fuel pump is not working, and low pressure may indicate a clogged fuel filter, a faulty pump, or a problem with the fuel tank. A high pressure reading could be a sign of blocked fuel line, bad fuel pressure regulator, or faulty
