Leprechaun
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transmission?
D40 STX fuel pump coming on when engine off
- Thread starter Mccnath
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Krankin
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Bluenavara
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I put my money on the very lengthy fuel return/fuel cooler system emptying for a few seconds after the engine is shut off, which is why a light tap on the tank may bring on a little extra dribble.
Note that the fuel return follows the path of the suction line almost back to the tank, and then it sweeps forward and to the opposite side, to under the drivers seat, where it coils into the cooler, then back again to the tank.
It wouldn't surprise me if the entire fuel return line and cooler is roughly 7-8 meters long. Return flow through this line would easily go on for a few seconds, after shutting down.
Note that the fuel return follows the path of the suction line almost back to the tank, and then it sweeps forward and to the opposite side, to under the drivers seat, where it coils into the cooler, then back again to the tank.
It wouldn't surprise me if the entire fuel return line and cooler is roughly 7-8 meters long. Return flow through this line would easily go on for a few seconds, after shutting down.
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Beergutz
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Have just read this thread and it is the good old mystery humming noise we have mentioned in other posts. Noise comes from passenger side rear wheel arch area near tank. Mine does it randomly too and sometimes when you close the door after sitting there for quite some time. It annoys the crap out of me as by the time I get down to try and find it, it bloody stops! I think Old.Tony and I thought it may have been a pressure relief of some sort. I did notice once before when I had stalling issues with faulty fuel filter o-ring that after my Nav stalled and the ignition was left on, for the duration of the hum coming from the rear I notice my tachometer needle lift and then drop back to the seated position when it stopped. That's why I reckon it's an electrical activated part. Keen as mustard to finally find out what it is.
That's the crazy thing. The ONLY electrical device on the diesel's fuel tank (if you haven't fitted a lifter pump to assist pushing the fuel through a second filter) is the fuel level sensor. That's it. There is nothing else there. I've just read through the manual for the diesel and the only connectors are:
Fuel filler tube (item 3 in the picture on p21 of FL.pdf)
EVAP tube (item 4)
Fuel feed tube (item 8)
Fuel return tube (item 9)
Vent hose (item 10)
So unless someone has fitted a lift pump, there is nothing electric-motor-powered in the region.
Unless ... and now this could be the case ... someone fitted a petrol fuel tank to the diesel and connected the fuel pump.
Fuel filler tube (item 3 in the picture on p21 of FL.pdf)
EVAP tube (item 4)
Fuel feed tube (item 8)
Fuel return tube (item 9)
Vent hose (item 10)
So unless someone has fitted a lift pump, there is nothing electric-motor-powered in the region.
Unless ... and now this could be the case ... someone fitted a petrol fuel tank to the diesel and connected the fuel pump.
not sure with the D40 but they usually breath out through the tank breather not the cap. they should have a valve on it which sometimes can stick or breather gets clogged.
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Krankin
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If that's the case, look to the Suction Control Valve on the pump.
Mccnath
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Ok so a new cap may or may not fix this, any idea how easy it is to get to this valve on the tank? And suction control valve on the pump, please explain?
Booked in for service Friday week so I want to get this thing over and done with and to make sure they have whatever bits they need in the shop to do it, as it's an hours drive to the dealer from where I live!
Booked in for service Friday week so I want to get this thing over and done with and to make sure they have whatever bits they need in the shop to do it, as it's an hours drive to the dealer from where I live!
The suction control valve is on the fuel pump and the dealer has to diagnose it. If you are talking with the service guy about it, mention that you've heard there have been some issues with SCVs on other D40s. They may not look, otherwise.
All the fittings on the tank are above it. With a body lift you can fit a hand in to get to things, but Nissan will probably empty your tank and drop it to work on it.
All the fittings on the tank are above it. With a body lift you can fit a hand in to get to things, but Nissan will probably empty your tank and drop it to work on it.
Mccnath
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Ok he said he would run diagnostics so all good there, have to call him back tommorow to let him know how I went tonight once I got home, left the cap off once home and haven't heard a thing. Be handy to get the valve on the tank done if it is the problem, save me another trip ! Still under warranty so should be right there one would hope lol.
dansD40
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Mine does same too, not really bothered been doing it for over a year now and nothing to come from it.. it is a mystery tho... Diesel bythe way
Mccnath
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Still waiting on a new cap from Nissan (ballarat vic) not entirely there fault - shipment went missing !! Cap definately has some sort of relief valve in it so when it comes in and i put it on I shall keep you posted as to how it goes 
longy509
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Mine does it as well 2011RX diesel .
It just does it randomly i was out around midnight the other night having a smoke and it started ute had not been running for 8 hours or so.
It just does it randomly i was out around midnight the other night having a smoke and it started ute had not been running for 8 hours or so.
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Bernie
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I've had my 2008 Navara (Diesel) now for only 2 months. Started making this noise after returning from a warranty fix that involved replacing a "fuel-pump valve" (no details available atm). I assumed that it was the fuel-pump cycling even though ignition turned off and that repair had added a wiring screw-up. I just got off the phone from from the dealer who says that Nissan say that this is a normal, non-electrical noise caused by a fuel-valve relieving pressure. This kind-of adds-up because I found it seemed to trigger when door or tailgate slammed, or car was rocked and also when I hosed the underside around the fuel tank.
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Found today the fuel cap is only vented under suction ie as fuel level drops. There is another vent hose from the top of the tank @ the rear going into a white plastic valve in the left chassis rail, my 07 has been making this noise for 3 years,
t.jarvis
Member
ok people, I am a diesel mechanic, to me, the sound is the fuel purge valve dumping excess pressure back into the tank, required on common rail diesel due to the need to maintain a constant high pressure in the common rail, diesel fuel does not have the cooling properties of petrol so it slightly expands under heat(rails are aluminum and suffer heat soak) to high a pressure can lead to a cracked rail ( go look at a Mercedes Vito van) the noise is normal and I will bet it only happens on a hot day or high engine bay temps
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