01 6.6 no fuel to filter

[BruceFritts]

Customer says crank but no start. Scanner says FICM not Communicating. Pulled FICM and sent to SIA outfit. They say FICM good. Reinstalled FICM, no fuel to filter unless manually pumped. Lift pump fuse good. Can here lift pump coming on/off when pulling fuse and relay. ?? Sucking air somewhere? Ideas?

[DmaxMaverick]

Welcome aboard!

Loss of FICM communication won't stop fuel to the high pressure pump. It may not fire the injectors, and may prevent high fuel rail pressure, but it won't cause fuel prime loss. Something else is happening.

If the 2001 has a fuel lift pump, it's aftermarket. It has no OEM lift pump. If the truck as an aftermarket fuel lift pump/system, look into that first for a fuel supply problem.

(Stock/OEM) Fuel, once primed, is drawn by the low pressure transfer pump in the high pressure pump. Purely suction, and it will not self-prime. Dual fuel tank models have a transfer pump between tanks, but no lift pump. The fuel primer pump at the fuel filter must be pumped until hard before a start attempt. It may require several attempts before firing and continued running, if the fuel prime prime was lost (leak, blockage, plugged fuel filter, ran out of fuel, etc). If you are able to pull fuel up to the fuel filter using the primer pump, then you should also be able to push fuel to the high pressure pump. If it isn't getting there, look for an external leak. If fuel is getting to the high pressure pump, but it is not making rail pressure, look for a control issue, or a failed CP3 pump, rail pressure regulator, or rail purge. If it is of these, it should/will cause corresponding DTC(s).

[BruceFritts]

Thanks so much. Yep, no lift pump at tank. Think I isolated an air leak on suction side. Reprimed and it's running now. Still can't figure why my scanner threw a no comms with ficm code at me. It will prolly be back. Hopefully not... Thanks again so much. Great forum here!

[DmaxMaverick]

You're welcome.

Where did you find the air leak? The quick connectors are the usual suspects. Once disconnected, they often don't reseal reliably.

The fuel system is very tolerant of air intrusion. As long as prime is not lost, it will pass quite a bit of air at a slow rate. This is usually only a noticeable issue when the truck sits for a long time, allowing air to collect enough to de-prime, or an air trap is allowed, such as some aftermarket filter systems.