Technical Noisy pump in tank of 500 pop ???

[5004ever]

So we fitted the QH pump and all was good - really quiet. 3 weeks in and it's getting noisy , more and more each day. If we stand 10 meters away from the back of the car we can easily hear that pump.
It is going to fail again.
Any suggestions as to why our car is eating pumps ???

 

[Ralf S.]

It does sound like you have a chronic problem. I'd guess the Continental pump was a replacement for a previous (even maybe the original) pump which was probably killed by this issue... but there's still something killing them.

If there's a bad earth (i.e. increased electrical resistance) then that would raise the voltage at the pump and burn out the motor.

I don't know where the pump is earthed on the 500... there will be some cable/harness bolted to the inner rear wing, or the boot floor nearby... perhaps under the rear seat cushion.. but you might have seen it if you've had the pump out. Remove the bolt, clean every bare-metal surface to buggeration and then refit it, with some Vaseline or other non-conductive grease on it, to keep it from corroding.

Failing that, splice in an additional earth wire from the pump's earth wiring and bolt that somewhere bare metal to act as a parachute. I don't know what voltage the pump uses but make sure the wiring is rated at least as high as the fuse controlling the circuit.


Ralf S.

 

[5004ever]

It does sound like you have a chronic problem. I'd guess the Continental pump was a replacement for a previous (even maybe the original) pump which was probably killed by this issue... but there's still something killing them.

If there's a bad earth (i.e. increased electrical resistance) then that would raise the voltage at the pump and burn out the motor.

I don't know where the pump is earthed on the 500... there will be some cable/harness bolted to the inner rear wing, or the boot floor nearby... perhaps under the rear seat cushion.. but you might have seen it if you've had the pump out. Remove the bolt, clean every bare-metal surface to buggeration and then refit it, with some Vaseline or other non-conductive grease on it, to keep it from corroding.

Failing that, splice in an additional earth wire from the pump's earth wiring and bolt that somewhere bare metal to act as a parachute. I don't know what voltage the pump uses but make sure the wiring is rated at least as high as the fuse controlling the circuit.


Ralf S.

Hello and thanks for that. Will check the earth for continuity against say a seatbelt bolt.

We have had the car for 2 years and 11months, 1 month left on the loan.
It had the Continental when we bought it, so that served us well, but then it whined and failed in the space of 5 minutes. The Delphi lasted 2 weeks and the QH is on its 3rd week but on the way out. We got re-imbursed for the Delphi, so not all bad.

Why is the FEBI so expensive, is it that good ???

 

[Ralf S.]

Febi is owned by Bilstein so it's got good pedigree behind it.. but Febi makes all sorts of stuff, from suspension arms to electrical components.

They're certainly not bad quality but I wouldn't rate them above Marelli or Bosch necessarily. I'd go with either of the latter if I was buying a pump to drive across the desert.. but only because they have a longer history and a wider repertoire of electrical accessories, so you'd hope/imagine they know more about making them. Febi for suspension, rubber and plastic components.


Ralf S.

 

[5004ever]

Febi is owned by Bilstein so it's got good pedigree behind it.. but Febi makes all sorts of stuff, from suspension arms to electrical components.

They're certainly not bad quality but I wouldn't rate them above Marelli or Bosch necessarily. I'd go with either of the latter if I was buying a pump to drive across the desert.. but only because they have a longer history and a wider repertoire of electrical accessories, so you'd hope/imagine they know more about making them. Febi for suspension, rubber and plastic components.


Ralf S.

Yes, more or less what I thought, though I was thinking of FEBI for suspension and brakes.
The Bosch pump is €144 and the FEBI is €334.

Makes no sense to us

 

[John202020]

It does sound like you have a chronic problem. I'd guess the Continental pump was a replacement for a previous (even maybe the original) pump which was probably killed by this issue... but there's still something killing them.

If there's a bad earth (i.e. increased electrical resistance) then that would raise the voltage at the pump and burn out the motor.

I don't know where the pump is earthed on the 500... there will be some cable/harness bolted to the inner rear wing, or the boot floor nearby... perhaps under the rear seat cushion.. but you might have seen it if you've had the pump out. Remove the bolt, clean every bare-metal surface to buggeration and then refit it, with some Vaseline or other non-conductive grease on it, to keep it from corroding.

Failing that, splice in an additional earth wire from the pump's earth wiring and bolt that somewhere bare metal to act as a parachute. I don't know what voltage the pump uses but make sure the wiring is rated at least as high as the fuse controlling the circuit.


Ralf S.

 

[5004ever]

Thank you for the earthing diagram.
Little update.
Took off the air filter box, 3 connection points. One which of course feeds air to the engine, one which is a breather pipe to the rocker cover and a third small pipe which I presume is for vacuum. This 3rd pipe is broken and no longer connected. Don't think it would destroy a pump so quickly though.

 

[John202020]

I'm trying to think of why the pump might fail, low fuel (over heating) ,poor earthing? But that would lower the overall dissipation in the pump, yes? Blockage in take up? Blockage in delivery to engine, Blockage in return to tank?

 

[5004ever]

We never let the fuel go below 1/4, most times never below 1/2.

Checked the earth with the multimeter and it's perfect.

Voltage reads as follows

Ignition on : 12.3v and then 0.
Start engine : 11.8v and then holds steady at 13.35v.

All this seems normal.

QH pump has been fitted for a month (2500km) and as noisy as hell.

 

[John202020]

I wonder what the pressure at the fuel rail is?
If you turn on the ignition and wait, does the pump run then stop? If you don't start the car.

 

[5004ever]

Yep, it runs, then stops

 

[John202020]

Yep, it runs, then stops

That rules out the pressure sensor/cut off

 

[portland_bill]

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.

Or cleaned up their old one, made it look new, returned it for a refund, so got a free valve. I've experienced this a lot with clutches, parts returned under warranty clearly much older than claimed, and not from the manufacturer I worked for. Victims of fraud.
Beware open boxes, stockists are not good at proper inspection of returned goods.

 

[5004ever]

The fuel from our tank must go around the circuit thousands of times !!!

We removed the back seat to have a good listen. The pump it going full speed at all times when the engine is running, whether we are at idle, cruising along or giving it some welly.

 

[5004ever]

So it happened. Pump failed at 4:25 am this morning.

 

[John202020]

So it happened. Pump failed at 4:25 am this morning.

Are going to return it or dismantle it?

 

[vexorg]

Pressure will only be around 3 bar. Dirty fuel or rust in the tank??

From earlier in the thread, it must run all the time, the engine would die in seconds without it running, no rest for the fuel pump.

 

[Ralf S.]

So it happened. Pump failed at 4:25 am this morning.

Sorry for your loss.... Pump died a hero's death.

It may be time to get an auto-electrician to look at it. If there's an earthing fault, then that may be quite easy to locate if one has all the metering/measuring equipment etc. It'll pay for itself if it saves you one more fuel pump.


Ralf S.

 

[5004ever]

Sorry for your loss.... Pump died a hero's death.

It may be time to get an auto-electrician to look at it. If there's an earthing fault, then that may be quite easy to locate if one has all the metering/measuring equipment etc. It'll pay for itself if it saves you one more fuel pump.


Ralf S.

Hello to all. In despair, we shelved the car for a few weeks. Now we have started to work on it, determined to clean everything. Let us say here that the exhaust is a bugxxx to remove - it's all rusted ogether. We removed a rear wheel and a wing liner and discovered the following part -- 46801183 --- variously described as a carbon filter or a vapour filter. From memory, it's not on the diagrams in ePer, and none of our normal parts suppliers sell it. We have purchased a new one on eBay. Suppose that after 13 years, it won't hurt to replace it.
Any thoughts on whether it could be the culprit ???

All 3 pumps (Continental, Delphi, QH) which we removed were very clean, but this time we are going to remove the tank and clean it, and also flush the fuel lines.
An extra earth on the pump is an easy modification and won't hurt.

Our son suggested to permanently connect the multimeter for a few days, and to set it on a max voltage setting. Sounds sensible.

Any other suggestions on parts which we should replace, and consider them as consumables after 13 years ???

 

[vexorg]

If the voltage is too high for the pump then you'd have had more serious issues. Pumps are very primative electrically, just coils of heavy wire.

Did you examine the old pumps to see why they failed?
Was it electrical or mechanical failure (short/open, or seized, etc)