Car came in with complaints of a hard starting in the morning. It was a service so fuel filter was replaced anyway (UFI) which made no difference. Bit of sniff and it'll start every time.

Only one code (sorry cant remember the P code will check and post) relating to low rail pressure. Sure enough when cranking the live data rail pressure was between 15 and 70 bar. On one occasion the rail pressure shot up and the vehicle ran.
The engine generally idles lumpy and has a hesitation, almost misfire during cruise (kangaroos, also suspect the dual mass is failing as there is a constant clutch smell and quite noisy operation)
Leak off test revealed one injector bleeding much more fuel than the other 3 cylinders (6-8 increments more) however no misfire codes yet so may not be related to the starting issue.
Knowing the common failure of the suction side of these CP3 pumps we hand primed straight to the fuel pump inlet and it starts every time, there is no electrical lift pump on this model.
May have jumped the gun a bit here and went ahead with a pump replacement (re-manned vetech)
NO CHANGE!

There is obviously a low side feed issue but we may have assumed wrongly (you know what they say about assumption!)

Is there anything on the low side which may be causing the fuel to drain back when left? check valve? possibly in the filter? The vacuum achieved by the pump slowly drops to 3 inches mercury, is this enough? We don't have any specs for this value so not sure if the re manned pump could be at fault however unlikely?

The car has been left with a separate fuel supply directly to the pump inlet so will see how it starts in the morning

Is there anything on this system i should have checked but have missed?

Look forward to your replies

Luke Browne

(sorry no engine code will post in the morning)