Fuel Pump Making Weird Noise When Car Turned Off In Hot Weather

[Rolls]

When I turn my car off in 37c+ weather the fuel pump makes this weird as hell vibrating whine, totally different noise to when it is priming or running though. I've even got a mate to be sitting with a multi meter ready and the pump is getting 0v but it still makes this weird as hell whining/buzzing/ringing noise for maybe 15 seconds after the car is switched off.

Only happens if the car has been sitting in the sun and I've been driving around town getting everything stinking bloody hot, could it be fuel boiling or something odd? Anyone experienced things like this before? The pump was replaced before I got the car but I believe it is a nismo drop in for an R32, it is however still using the stock wiring loom and getting ~11v.

Ideas?

[scotty nm35]

The fuel in the rail evaporating, causing the one way valve in the pump to release pressure? Do you have a gauge on it?

[GTSBoy]

Yuh, it's the check valve leaking down. Normal.

[abr33]

37 is cold!

[GTSBoy]

Well, it's 42 here today. It's certainly not cold outside. Stepped out an hour ago and suffered a dehydrated eyeball in the first 2 seconds. I kept the other eye closed, just in case.

[discopotato03]

Just out of interest could you could try releasing any pressure in your tank by cracking the filler cap before you shut down .

[Rolls]

I can try that, is the fuel evaporating a bad thing?

[ARTZ]

Damn pressure from.opening my half full tank today almost blew me away...

[scotty nm35]

So hook your damn carbon canister back up Artz.

[discopotato03]

Pressure in the fuel tank doesn't help .

A .

[abr33]

So hook your damn carbon canister back up Artz.

Mine holds heaps of pressure and I have carbon canister still?

[scotty nm35]

It's not working then.

The carbon canister is only a part of the evacuation circuit that sucks all the fumes from the tank and into the manifold. There should always be vacuum in the tank, (which is sometimes mistaken for pressure) or the system isn't working as designed.

[discopotato03]

My old Zoob RX Turbo used to pressurise its fuel tank in hot weather and if it was real hot (hight 30s/40 like today) I didn't tighten the cap . Its hardly going to fall out and I'd nip it up if I stopped anywhere .

I think you can get weird things happening because the pump is trying to return fuel to the tank which is at higher than normal pressure .

I think some of these problems occur because the fuel pump is circulating a lot more fuel than is necessary for the power being used and its possible that at low speeds the steel fuel lines may be absorbing some radiant heat from baking hot roads .

I think manufacturers have sometimes integrated a heat exchanger into the air con system because of fuel temp problems in hot hot weather , may have been an early V12 Jag can't remember .

A .

[JustinP]

When I turn my car off in 37c+ weather the fuel pump makes this weird as hell vibrating whine, totally different noise to when it is priming or running though. I've even got a mate to be sitting with a multi meter ready and the pump is getting 0v but it still makes this weird as hell whining/buzzing/ringing noise for maybe 15 seconds after the car is switched off.

Only happens if the car has been sitting in the sun and I've been driving around town getting everything stinking bloody hot, could it be fuel boiling or something odd? Anyone experienced things like this before? The pump was replaced before I got the car but I believe it is a nismo drop in for an R32, it is however still using the stock wiring loom and getting ~11v.

Ideas?

I know the exact noise you mean, my motorbike has always made the same noise when its hot, from new. Sometimes even 24 hours + after driving it.

[abr33]

It's not working then.

The carbon canister is only a part of the evacuation circuit that sucks all the fumes from the tank and into the manifold. There should always be vacuum in the tank, (which is sometimes mistaken for pressure) or the system isn't working as designed.

Now that you mention it, that might be the case. Will investigate.

On a similar topic why does my car stall after first start particularly when cold?

[GTSBoy]

Idle air valve sticky. Takes a moment to open up far enough to stabilise idle. Moment is too long. Clean up the valve so it moves faster and maybe it will react fast enough to catch the idle.

[abr33]

Idle air valve sticky. Takes a moment to open up far enough to stabilise idle. Moment is too long. Clean up the valve so it moves faster and maybe it will react fast enough to catch the idle.

Ok, Thanks

[jiffo]

Some strange replies here so I'll add mine.

While the car is running, fuel is circulating in the rail at pressure controlled by the fuel reg.

Turn the engine off and the rail stays at pressure, maintained by the fuel reg at one end and the fuel pump at the other.

All good.

Now heat soak the fuel rail and that petrol will quickly expand, it has nowhere to go but to open the fuel reg and discharge to the tank.

The noise you're hearing is the pressurised fuel slowly bleeding through the reg back to the tank until rail pressure has stabilised.

Nobody else experienced vapour lock back in the old carby days?

[ARTZ]

But no Carbon cannister is worth +1000 street creds.

but seriously my carbon canister has carbon falling out of it when i turn it upside down...is that normal?

I'm quit happy to reinstall it if I know it works..I love having more junk in the engine bay to make life hard when I am working there..

[Rolls]

Thanks for the explanation jiffo, makes sense now.