Jaguar Forums - Jaguar Enthusiasts Forum - Restrictive Performance DSC not Available P1338 Fuel Pump Driver Module

Quote:

Originally Posted by Datsports (Post 2076476)

it will be the BMW's target pressure .
between the jags fuel pressure regulator and the fuel pump driver it will aim for 55psi .

as for the XJR & STR they too run on 55psi , and the higher fuel pressure you speak of is only for under boost conditions ,
and is achieved via a second fuel pump driver and a second identical pump that kicks in under boost conditions . to combat boost negating the fuel pressure at the injector .

The x350 xjr's two pumps actually run and are controlled together in parallel, they are not like the X308 xjr's pumps where I understand the second pump is only brought in under high fuel load conditions.
The pumps on the xjr like all x350's are fed with a PWM signal and are in effect variable volume with no fuel return line. The duty cycle is varied to both pumps to change fuel delivery as required by the rail pressure sensor/ECM.
The operation of the system is fully explained in the x350 technical guide, extracts of which are in post 7 of this thread;
https://www.jaguarforums.com/forum/x...adings-199546/