Technical Noisy pump in tank of 500 pop ???

[5004ever]

Hello to all.

The in-tank pump of our 1.2v Fiat 500 pop failed 2 weeks ago. As the car is from 2009, we didn't mind replacing it as we felt it had served a good long time.

We bought a Delphi unit, correct part number , and we made the tool to unscrew the pump ring.
All went well.
Ignition on, pump primes the engine, pump stops, car starts and runs well.

This week, we noticed that when the engine is running, the pump is whirring all of the time.

We don't remember this amount of noise from before, we do not remember that the pump ran continuously.

Is our memory failing ??? Is the pump supposed to run all the time while the engine is running ?

 

[John202020]

How much fuel is in the tank?
How much fuel is usually in the tank never a good idea to run with low fuel all the time.

 

[5004ever]

I mostly run it between half and full. It's 3/4 at the moment

 

[John202020]

I mostly run it between half and full. It's 3/4 at the moment

Hi thank you that rules out low fuel causing the pump to be noisy, its running, has the correct pump, I'd run for a few months and see how it is?

 

[5004ever]

Oki doki, thanks for that. I wasn't certain that it was normal for the pump to run all of the time. I thought that maybe it worked along with the injection pump to maintain pressure and that after startup the injection pump was good on its own

 

[puntodeltathema]

Fuel pumps can be a bit on the noisy side on the 500 - partly because they're not very far away from you in the cabin and there isn't a massive amount of sound insulation. Maybe your previous one wasn't noisy enough because it was failing!

 

[chris3234]

Oki doki, thanks for that. I wasn't certain that it was normal for the pump to run all of the time. I thought that maybe it worked along with the injection pump to maintain pressure and that after startup the injection pump was good on its own

They do not have a injection pump the petrol engines just the one in the tank as they don't inject the fuel st very high pressure unlike s diesel engine

 

[varesecrazy]

I have to agree our 2018 500 has the loudest sounding pump of @15 similarly kit equipped other FIATS...

But its our only 500

 

[Ralf S.]

The pump on the Younger Mrs S' Rasputin (1.2 benzina) is dead quiet.

A pump runs all the time, since that's the only way it can keep fuel rail pressure up. If the engine doesn't need that fuel, the regulator feeds the fuel back to the tank.

The problem might be because it's a Delphi unit rather than an OE Fiat one. Delphi is "not bad" but ultimately it's a cheaper part and something has to give (even allowing for the notoriously expensive Fiat packaging that the OE pump arrives in).

It might quieten down as it beds in... otherwise get some thick dog blanket/insulation etc. and lay it over the floor, under the rear seat base... as long as the seat can still click shut.. that'll help to muffle it.

Ralf S.

 

[5004ever]

Well, it broke down at the side of the road this morning. Pump not working. Less than 2 weeks of use.
Is there not some sort of pressure sensor that allows the pump to rest occasionally ?

 

[5004ever]

The previous pump was branded Continental

 

[5004ever]

And the replacement pump was Delphi FG1061-12B1

 

[John202020]

And the replacement pump was Delphi FG1061-12B1

Take it back and ask for a replacement saying it failed after a very short time?

 

[Ralf S.]

Well, it broke down at the side of the road this morning. Pump not working. Less than 2 weeks of use.
Is there not some sort of pressure sensor that allows the pump to rest occasionally ?

The "pressure sensor" is the fuel regulator on the injector rail. When it builds up too much pressure, it diverts fuel back to the fuel tank.

What you're asking for is the opposite of a high pressure fuel injection system. If the fuel pressure was "sufficient" and the pump turns off.. then as soon as one of the injectors has fired then the pressure would drop and the pump would have to start up again, to get the pressure up. Then it would turn off again... But then another cylinder injector would immediately fire, which would start the pump all over again.

All that would happen is that the pump would continually be either shutting down or starting up.. so the mean fuel pressure would be reduced and your car wouldn't make as much power. Someone would then invent a system where the pump runs continually, to keep a constant high pressure.... which is what you currently have.


Ralf S.

 

[John202020]

If I turn on the ignition and wait the fuel pump runs then stops after about 5 seconds, if that's any help cannot tell once started as the engine drowns out the noise.

 

[chris3234]

Well, it broke down at the side of the road this morning. Pump not working. Less than 2 weeks of use.
Is there not some sort of pressure sensor that allows the pump to rest occasionally ?

Why would it rest while the engine is running?
If the pump isn't running there no fuel flowing within seconds any pressure in the rail would have Been used up injecting fuel into engine especially at speed/high rpms

Remember of these engine's the in tank pump is the only way to get fuel into the engine

 

[5004ever]

Oki doki, thank you all for the explanation, much clearer now. We have been running diesel cars for the last 20 years, so that's why the Fiat system is new to us.

On ePer, our part number is 51806983.

We cross-referenced this where we normally buy parts and here are our preferred choices

Magneti Marelli 519700000185
VDO 228-235-106-001Z
Pierburg 7.02701.88.0
QH QFP915
Mapco 22056
Vemo V24-09-0009
Bosch 0 986 580 947
Valeo 348747
Metzger 2250350

There is also a FEBI 45469 , it's by far the most expensive.

Any opinions would be most welcome.

 

[Ralf S.]

Marelli tend to be good and is an original "Fiat" parts supplier
VDO makes a lot of instrument/clusters (some Fiat amongst them), so I'd trust them to be able to make a fuel pump.
Pierburg make all the original "Fiat" emissions control sensors, so I'd trust them to be able to make a fuel pump.
QH, Mapco, Vemo and Metzger... tend to be "pattern parts" suppliers rather than OE.. but probably okay and thousands out there.
Bosch makes electrical everything, so I'd trust them to be able to make a fuel pump.
Valeo, I never bought more than once, in a good way...so I'd trust them to be able to make a fuel pump.

On balance, Bosch... since it's more "their thing".. but depends on the price.


Ralf S.

 

[5004ever]

Thank you for that.
We had slimmed it down to similar results. Marelli was our preference, but it was out of stock. It was then down to Bosch and Valeo, and the QH was more expensive than both of those. However, we eventually found the QH from another supplier at a very good price this morning, so we went for that. As we had removed a Continental, we guess that it was not the original pump either.


Wonder why our 2 week old Delphi failed

 

[Ralf S.]

It could just have been a wrong 'un..

I bought a central heating diverter valve last year that worked for a couple of days and then turned weedy... it took for ages to work out that it had failed, even though I had the same but different symptoms to the one that it had replaced.

In the end, a third valve solved my heating woes.

It did come in an open box, so my theory is that someone fitted it, found it didn't work without understanding why (I hope!) so returned it to Screwfix and then I bought it...


Ralf S.