Singing fuel pump

Maybe the fuel pressure regulator needs changing. I can imagine it changing its whine when a new pump is fitted as the pressure going into it might change

Just my 2p
 
Watching with interest.

I just picked up a 46K mile Rockster with similar symptoms.

The pump pressurises the system fine when the ignition is turned on, and then goes quiet: however once the engine is fired up it is running constantly.

I'm confused about why the pump would need to run constantly ONLY when the engine is running. If there was a leak in the pressurised system then surely it would leak all the time, (and thus cause the pump to run all the time), not just when the engine is running??

FWIW when I replaced the fuel filter the one in there might have been the original.... the date stamp on it (circumstantial evidence I know), was 06.11.02! (I had hoped that a very old/blocked filter might have been the cause of the whine).
 
I'm confused about why the pump would need to run constantly ONLY when the engine is running. If there was a leak in the pressurised system then surely it would leak all the time, (and thus cause the pump to run all the time), not just when the engine is running??.

Firstly the initial running of the fuel pump to prime of the fuel rail when you turn on the ignition is a timed function controlled by the Motronic. It’s a dumb system, So even if you had a fuel leak, the pump would still only run briefly.

(If there were an electrical fuel pressure sensor in the system, then the fuel pump could be controlled to run to replace the lost pressure, but there isn’t.)

Secondly when the engine runs, the fuel pump will run constantly. The pressure in the fuel rail is maintained by the pressure regulator which passes excess fuel back to the tank.

Hope this explains.
Ian
 
Firstly the initial running of the fuel pump to prime of the fuel rail when you turn on the ignition is a timed function controlled by the Motronic. It’s a dumb system, So even if you had a fuel leak, the pump would still only run briefly.

(If there were an electrical fuel pressure sensor in the system, then the fuel pump could be controlled to run to replace the lost pressure, but there isn’t.)

Secondly when the engine runs, the fuel pump will run constantly. The pressure in the fuel rail is maintained by the pressure regulator which passes excess fuel back to the tank.

Hope this explains.
Ian

That makes a lot of sense.

Sounds like it's a dying pump then.

250 quid to motorworks then....
 
Mine is still singing

Maybe you don't need to rush to change it, mine has been singing for months (I know, I know, once the house painting has finished I will get round to checking it), doesn't seem to have affected the running at all. I did look at the fuel pressure regulator, well I looked for it in Haynes, which doesn't mention it all, got as far as remove gearbox cover in the Clymer manual and realised it wasn't going to be a quick job!

I promise I will follow the advice given so far before asking any more questions.
 
Maybe you don't need to rush to change it, mine has been singing for months (I know, I know, once the house painting has finished I will get round to checking it), doesn't seem to have affected the running at all. I did look at the fuel pressure regulator, well I looked for it in Haynes, which doesn't mention it all, got as far as remove gearbox cover in the Clymer manual and realised it wasn't going to be a quick job!

I promise I will follow the advice given so far before asking any more questions.

I was hoping someone would say that tbh!

Currently out of work and job-seeking, so extra costs aren't what I want to be dealing with. Hopefully it'll stay usable for a while. I have to say that I've only had the bike a couple of weeks and didn't notice the pump whine when I test-rode it, so I'm hoping it's only just started happening.
 
Its all gone quiet!

Well, my fuel pump has finally shut up. I am wondering if it wasn't a squealing capacitor? I had let the battery go flat and after a cycle on the charger, bike started up and annoying singing/whistling noise has gone. Could it be that by "letting" the battery go flat the capacitor discharged?

If it happens again, I will just disconnect the battery and see if that works.
 


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