Rising Rate Fuel Pressure Regulator Noise

[Dangerdoc]

interseting one:

New rising rate fuel pressure regulator from RPi (can see why you all know it as RiP)

So, Range Rover 3.5 EFi, Flapper, Mallory Hyfire 6A ign and Promaster Coil, high quality leads, properly tuned, new engine (yes the one we had many posts on before )

At rest idling in neutral, silence, just the normal running of a lovely V8.

At rest, in gear, braked, silence, as the previous line.

In gear, moving, regardless of speed, but relative to accelerator demand - sounds like a jet engine - high pitched whine, audible clearly outside the car - turns heads for the wrong reasons this thing.

No air leaks, all very very carefully checked, no kinked hoses, no fuel leaks.

When accelerating - inside the vehicle you can hear an unusual flow noise like what one would expect when hearing turbulence (hey - same as a heart murmur across a tight valve !!!).

So any wizards out there heard this nonsense. Been ages since the unit was purchased so sending it back to RiP is no use really.

Open to questionning / interrogation / suggestions (hmmm need to watch what and how one is suggesting things on here )

Doc

[Coops]

you tried it with the stock reg to eliminate or point the finger at it?

[Dangerdoc]

Ta for that Q, but nah, sadly the original has been binned a while back.

As it was buried way at the back of the heads I felt that it was a pain in the derrier or whatever the Frech call it, and the new rising rate one was fitted.

Never noticed it when I got it back from the tuning garage.

I really feel like stripping off all the flaming petrol stuff and getting the thing fed only on LPG as this is my project car and not the main one.

D

[Coops]

has it been fine while its ben fitted? or has it played up from day one?
if so are the pipes on the right way round?

[Dangerdoc]

You know, I never really noticed it on the way back from the tuners as the stereo was, well ..... a bit cranked up and my mate and myself were having a riot about other matters.

So....never really listened to the thing on the way back and that means ... well.... I don't know if it made a real hooley of a noise but it is definitely loud now.

Thinking back, there may have been a little noise but the guys in the garage were sorting out a rather noisy beastie and that may have muffled the damn thing.

Funny how you get distracted from the important things and just assume that the beastie was ready to roll full on - ahem i mean ran in gently.

Sorry to be so very vague but I honestly don't know.

I did wonder if I should maybe flip the pipes over but I did not know if that would damage the thing and thought guidance in here would be the best idea.

Ta

[Coops]

if i remember rightly.
on my fse adjustable reg, the return pipe from the fuel rail goes to the side fitting, and the bottom fitting goes to the return pipe to the tank,

[ramon alban]

hello doc, long time gone, I've been elswhere.

I think, from your signs and symptoms as described, you have two faults both unrelated to rrfr.

1 that high pitched whine, soon to be heard by the occupants of the Mia space station, relative to accelerator demand (otherwise known as engine rpm) is due to a noisy drive belt (fan, steering pump, A/C?), or alternator bearing or fuel pump bearing or similar internal pump problem. Flood everything includuding belts and bearings thereabouts with wd40 hoping to affect the noise or make it disappear - if so take the appropriate corrective action.

2 that noisy flow of turbulent liquid heard from inside the cabin is due to bubbles in your heater matrix which is accelerated in sympathy with water pump speed or engine rpm. a sort of high speed multiple embolism.

its just possible both faults are linked by extreme cavitation inside the water pump generating loadsa bubbles because its knackered and thereby also causing the sympathetic whining noise.

Regarding the rrfr it seems you might have jumped into a parallel universe because you do not report any efi system issues such as rich/lean behaviour, choking, stalling, what have you, that might be linked to a fuel pressure issue.

Indeed from what you say its running OK as is your stereo system.

Oh, and dont flip any pipes because it seems like a good idea, do some checking of the arterial and venous diagrams first.

Where did you say you did your doctoring?? review your diagnosis dear boy!

I'm probably wrong, but it seems sorta logical to me?

[Eliot]

If you want to test the pump and regulator without the engine running to eliminate things, do the following:

Pull the relay or disconnect the feed to the fuel pump and run a direct 12v to the pump - this will get fuel circulating at the same conditions as Wide open throttle(WOT).
Why? - Because the fuel regulator uses vacuum to control the flow, when the engine is at WOT there is little or no vacuum - exactly the same conditions as when the engine isn't running at all.

To test it at other conditions, you need a small syringe (or a mityvac) to get a vacuum at the input of the FPR - then you will see the fuel pressure reduce as you apply more vacuum to the FPR.

[Dangerdoc]

Hi guys,

Ta for that.

first off: Ramon, thanks for the input but.....

1. Waterpump brand new. 2. Alternator same, brand new.

Listening in the engine compartment reveals no unusual noises from cavitation flow or indeed belts etc... very carefully looked for that at the beginning.

The RRFPR is clearly noisy as when giving it throttle with the vehicle stationary and the bonnet open then it can be heard with this high whistle type noise - definitely like a jet.

The thing can be silenced (when stationary at least) by holding the thing between fingers - strange I know but I was wondering if it might just be a resultant harmonic from the flow and maybe need some more securing.

This holding of the RRFPR can't be done when driving - one wonders how obviously I needed to state that really!

So it is definitely related to flow. I will do a couple of things today.

1. - Over-secure the thing in it's current location and 2. try the fuel pump idea from Eliot.

Thanks guys as ever - always grateful indeed

Doc.

[Ian Anderson]

Perhaps a piece of crud in the valve / pressure unit. If it is trying to regulare and some crud is i the way it will not be able to fully close the bypass. So the fuel hisses past the crud.

Worth while taking it off and seeing if any crud falls out of the unit (I et you wish you could do that with the parts on your patients!)

Ian

[Dangerdoc]

Ah ha !!!!!

Took the unit off the firewall bulkhead by unbolting the two self tapper hex heads that were holding it on with its original metal plate bracket.
Fired the beastie up and not a peep, which is normal for the first few minutes.

Now let it warm up to normal temp, and hey presto - silence. Not a whimper.

One wonders - either that nasty little ol' bit of crud has shifted in the process or indeed it was resonant harmonics being set up by fuel flow and vibration amplification via the bracket and bulkhead which would reason why it was so loud in the cab.

Now - going to mount the thing back in the relative same position but with a flexi-block to dampen the vibrations.

One wonders???

Hmmmm, anyone heard of this nonsense before ?

[ramon alban]

The thing can be silenced (when stationary at least) by holding the thing between fingers - strange I know but I was wondering if it might just be a resultant harmonic from the flow and maybe need some more securing.

Like I said, Doc. I was probably wrong even if it was based upon your described symptoms and now that you say you can attenuate the noise by squeezing the rrfr with fingers this adds a symptom hitherto not revealed.

That changes everything - I reckon, but you gorra admit it there was a degree of logic, from a distance, until the new info arrived.

I can see Eliot's suggestion working well regarding peak flow, and the reduced flow with vacuum applied, but it would not emulate the effect of the injectors regular opening patterns inducing a resonance in the fuel rail which could harmonise with the natural rrfr rhythms.

This screaming is clearly new since the rrfr was fitted so reverting to a cheap S/H regulator from a scrappy may resolve the issue in terms of source.

Could there possibly be other reasons for resonance in the fuel line such as fuel pump cavitation or the already mentioned partial (whistling)blockage or the way the rrfr is mounted, which once it becomes established would be "alterable" by squeezing the rrfr thus modifying the resonant frequency of the system, but without pointing to the rrfr as the faulty component.

Further idea, what happens to the noise when you change the pressure settings of the gizmo.

Finally, is there any possibility of capitalizing on this resonance. particularly if you can find a way of influencing it to change pitch, produce your own melodies and bin the stereo.

Ramon

[Dangerdoc]

Hey Ramon,

Excellent logic as ever.

It usually brings a smmile to my face when reading your posts. it does amaze me how deep your knowledge of the injection system and faults are.

Most rewarding indeed.

I don't dare try altering the pressure regulation nut at the top of the thing as that will change the fueling and I don't have the knowledge nor equipment to set these things up. That's why it went to the tuners in the first place. Mates and myself fumbled, hacked, bashed and lamented a good few expletives to get the old engine out and the new one in.

Now it needs settling down, running in and then a final tune up to get the thing up to speed. There is no way, however that I will take it back to the guys who did the initial "tune up" as there seemed to be so many "devious" faults along the way.

I am sure you remember well the saga and multiple postings about this rabid mongrel.

For the minute it will be set to run like it is with the RRFPR mounted on a shock block to dampen the harmonics.

Dare I say it, I am even contemplating booking the car into RiP for them to set up the LPG again and maybe they can shine some light on their noisy kit.

Whats the consensus on taking the car to RiP guys? A wise or foolish option as I cannot set the gas up to run properly as I daren't let it run too rich or too lean.

Maybe that should be in the LPG section? Hmmmmm.

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