P1089 Fuel Pump Fault Code

P1089 Fuel Pump Fault Code – Nissan Patrol ZD30CRD

Fault Code P1089 in Nissan Patrols can be a real annoyance, because ultimately the ECU has registered that the fuel rail pressure is not within acceptable tolerance (in terms of the target rail pressure). Therefore, it has lodged a code to say that the fuel pump is not doing its job.

The issue with this particular model is that nine times out of ten we find the pump is not the problem. The injectors are the culprit because they may suffer excessive leak-back. There is also a pressure limiting valve within the fuel rail, which can also leak, and because it doesn’t leak externally, you can’t see it. It just leaks through the leak-off back into the fuel tank.

Whenever we get this P1089 code, the first thing we do is make sure that at idle there is no fuel whatsoever coming from the pressure relief valve. This relief valve is not due to open until 2000 bars, so if you have any fuel flowing from there at 320 bar (approximate idle pressure), you obviously have an issue. Also with the leak-back for the Bosch fuel injectors, at idle we don’t want to see any more than 20cc’s per minute. 8-10 is quite normal, a dead injector or a couple dead injectors, but a single dead injector will flow something like 300cc’s per minute at idle if there is a problem. Hence, it’s very stark and noticeable.

Double check these things first, and then before changing the complete pump, we would suggest changing the suction control valve first, or the inlet metering valve. This depends on who you talk to, because on average that is usually the issue before the pump is. So I hope that provides some help.

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