D40 STX fuel pump coming on when engine off

[Mccnath]

Hi guys , I have a 08 stx navara and was hoping someone might know why the fuel pumps keeps coming on even after the engine is switched off and car is locked! It only runs for about 4 to 5 seconds and I've noticed if u lay under the vehicle and tap the tank , that also will make the pump come on for 4 to 5 seconds. Even if the car has not been running for 24 hours this still happens! Nissan don't seem to have heard about this problem so I'm fingers crossed on here lol. Cheers nath. Ps no power is lost or limp mode problems, car still runs perfect, just annoying when it's turned off and u keep hearing this fuel pump cutting in!!

 

[Arty_74]

Hi guys , I have a 08 stx navara and was hoping someone might know why the fuel pumps keeps coming on even after the engine is switched off and car is locked! It only runs for about 4 to 5 seconds and I've noticed if u lay under the vehicle and tap the tank , that also will make the pump come on for 4 to 5 seconds. Even if the car has not been running for 24 hours this still happens! Nissan don't seem to have heard about this problem so I'm fingers crossed on here lol. Cheers nath. Ps no power is lost or limp mode problems, car still runs perfect, just annoying when it's turned off and u keep hearing this fuel pump cutting in!!

Yes I have noticed the same thing on my 08 STX, anyone have any ideas?

 

[Krankin]

Not a 100%, but if its normal, I might say its to keep the fuel pressure up..

as for nissan not knowing, well say no more on that matter,
come and get your answers from Navara.asia

 

[tweak'e]

Yes I have noticed the same thing on my 08 STX, anyone have any ideas?

afaik theres no electric fuel pump in those diesel navaras.

your probably hearing something like the AC fan kicking in.

 

[Krankin]

afaik theres no electric fuel pump in those diesel navaras.

your probably hearing something like the AC fan kicking in.

that'd be odd then...the ac fan comes on when u tap the fuel tank

 

[Arty_74]

Definately not the a/c fan, it does it when the car is off and the key removed.

 

[tweak'e]

that'd be odd then...the ac fan comes on when u tap the fuel tank

i doubt its related.

i would think by the time you crawled under to check the tank, the heat soak causes water temps to rise which trips the fan.

 

[JPMC]

Doubt it would be the fan.

My guess is it's the pressure equalizing valve in the fuel tank adjusting so the fuel tank doesn't blow up like a balloon.
I hear mine every now and again, no where as bad as a Honda my wife used to drive which sounded like a cow.

 

[Krankin]

i doubt its related.

i would think by the time you crawled under to check the tank, the heat soak causes water temps to rise which trips the fan.

"Even if the car has not been running for 24 hours this still happens! "

 

[mitch92]

Umm yea why the A/C fan tweake? if car is off then it won't run??? certainly not after 24hrs.

 

[Mccnath]

It definitely isn't a/c fan, it cuts in (in the fuel tank) right when I'm laying under it , it's obviously in the tank! It's booked in for 45 thou km service in next 2 weeks. Still under warranty so really want get this thing nutted out so il have some ideas to throw at the genius's at Nissan! I'm thinking tho there shouldn't be any power to the tank or fuel pump when the vehicle is locked or should there be??

 

[tweak'e]

was thinking AC fan as some vehicles will turn cooling fans on if the engine is hot. not uncommon for them to turn on from heatsoak.
navara main fan is mechanical so that only leaves AC fan.

f its on 24hrs later its not going to be the fan.

not sure where the breather is plumbed to on the D40, maybe a bit of air pressure or tank vacuum making a noise when air comes in/out.

i would record the sound so we can hear what sound your referring to.

 

[Mccnath]

Pressure equalising valve makes sense if it has one and designed to do so, tapping on the bottom of the tank setting it off tho is still a concern to me, maybe it's just very sensative!!

 

[Mccnath]

Also it seems to be occur alot more after a long trip. Can cut in and out for for to five seconds every 10 ~ 15 minutes, this happens for hours after the vehicle is switched off and locked

 

[Old.Tony]

I've just read through this thread twice and there's no mention anywhere of this being a diesel at all, it could be the petrol version.

The petrol version has a pump in the fuel tank. It is integral to the fuel level sensor. It is described in the manual as "turbine type design fuel pump".

On the diesels, the fuel pump is located up behind the top of the engine just in front of the firewall, with the primer bulb beneath it. If they'd install a pump in the fuel tank, we wouldn't need a primer bulb in ours!

I'm going to assume that we're talking about a petrol car here. It is likely that the relay for the fuel pump is erratic (probably damaged). It's likely that this is the culprit.

 

[Mccnath]

Sorry, yes the d40 is a diesel. So there is no pump in the tank on a 08 STX D40? Only in the engine bay?

 

[Krankin]

and Arty's is a TD also

 

[Old.Tony]

On a diesel, there is (usually) no pump in the tank. There's a relief valve for pressure. There was some discussion here about fitting a lifting pump outside the tank if you fit a second fuel filter. Is your vehicle second hand, and does it have two fuel filters?

The relief valve may open and close from environmental variations, but it is unlikely to open in the patterns you have described and especially after 24 hours!

I would still have the diesel's fuel pump relay checked.

 

[Mccnath]

Yes I bought the vehicle 2nd hand, a year old. Not sure if it's had a second lift pump or filter fitted, a little hard to see from underneath. Maybe it could have though as the noise was clearly a pump. Best still tho to get the genius's to check the wiring relay and plug their gear in and check it out.

 

[Mccnath]

Wondering if Arty's has had second filter / pump added !!