Need a complete descition of the fuel pump control unit/Modulator

[Infinitiguy19]

Hi i think my fuel pump Modulator is bad can you tell me if it controls the pressuization of the tank and the low fuel sensor?

thanks

[maxnix]

No, if I understand your question correctly, it does not.

Be sure to search all three forums, IG, Q45, and IOM with FCPU in the text body, both recent and archived.

Helps to read the FSM first.

Welcome to NICO, the manger for Q45.

[qsiguy]

There are a lot of posts on the subject and they discussions can get lengthy so I'd hate to type it all out again.

No, the FPCU does not have anything to do with the pressurization of the tank or the low fuel sensor. All it does is control the speed of the pump based on RPM/load of the engine.

The FSM (Factory Service Manual) will explain it in great detail and is available for free on this site and others if you don't have it.

[Infinitiguy19]

For new members:

Issue fixed: The mechanic installed a longer screw than the orignial. And after that the the fuel tank could'nt hold any pressure because the air would escape from the tank.