Fuelpump cutting out around 4000 rpm

[tm40000]

Hello, why does the Power (the relay starts clicking) to the fuelpump start to cut out around 4000 rpm? I´ve changed the relay, the main ECU relay but no difference at all. /Thomas

[gbtvr]

Long shot, but does it also happen when in neutral, or just under load, thinking it may be the pump struggling to maintain the flow required and a low pressure taking you out, worth checking pump flows ok if not doing in neutral.

If in neutral as well, there could be pressure issues, do you have blitz racing software by any chance to monitor what is happening with all readings?

[davep]

tm40000 said:

Hello, why does the Power (the relay starts clicking) to the fuelpump start to cut out around 4000 rpm? I´ve changed the relay, the main ECU relay but no difference at all. /Thomas

The relay's coil has + 12 Vdc (battery) on pin 86 and is energised by the ECU sending pin 87 to earth (pin 16). If the contact is clicking or bouncing I'd check the continuity of these two circuits making sure all the connections are secure and clean.

[tm40000]

No difference under load or not so I imagine nothing wrong with the fuelpressure.

I´ll check the ECU ground, thanks.

What about the immobolizer? Could something be wrong with it that causes the relay to start breaking the fuelpump Circuit?

[Aussie John]

How about the wiring on the switch behind the glovebox.