HEMTTs . . .It’s Prime Time for Fuel SystemPosted: 2015/20/05
Mechanics, you should never, ever, use a pressurized air hose to prime the HEMTT’s fuel system.
That adds too much pressure too fast. You can jam the pressure relief valve shut, all while pressure continues to build.
The vehicle’s fuel system is designed for suction from the pump side, not pressure from the tank. Not only will using an air hose cause leaks, but the added pressure can split the seams in the HEMTT’s fuel tank!
If you have a base or A2 HEMTT or an A1 wrecker that needs to be primed, use the priming (hand) pump, NSN 4910-00-402-9623. Make sure you follow the instructions in TM 9-2320-279-14&P (IETM EM 0290, Jun 09) for base HEMTTs and the A1 wrecker and TM 9-2320-325-14&P (IETM EM 0289, May 09) for A2 HEMTTs. You’ll find the info under “Services Upon Receipt for an Engine Out of Fuel.”
A4 HEMTTs have a built-in fuel pump. If your A4 HEMTT loses prime, follow the operator maintenance procedures in TM 9-2320-326-14&P (IETM EM 0288, Oct 08). You’ll find them under the “Priming Fuel System” track.
These instructions are also listed in the operator’s manuals for each of the A4 HEMTT models.