Noisy Aeromotive FPR

Recently my Aeromotive FPR starting whining at idle and sometimes while driving. Engine runs great and AFR is spot in with zero hiccups. Thought it could be cavitation so I installed DEI insulation to the fuel lines near the engine. Inspected the FPR diaphragm and it looks fine but replaced it since I had a new one. Pressure is ~29-33psi at idle.

Is the noise caused by the fact that it is a return less system? The noise popped up about a year ago then went away until recently returning.

- DMCH stage 2 engine | automatic
- Holley Terminator X ECU
- Bosch 62545 injectors
- DMC modern fuel pump
- DMC replacement fuel accumulator in 2023 before EFI
- Factory spec ignition
- always run 93 octane

Attachment 72055Attachment 72054

Interesting you have a non return pressure regulator. Do you have something to limit the fuel pump pressure. My fuel pump blocked is over 100 PSI.

I do not besides the regulator.

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Originally Posted by Timeless

I do not besides the regulator.

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I would think that puts a lot of heating and wear on the fuel pump. I would think you need a pressure regulator (return type) at the pump. Or a PWM fuel pump controller. Probably would set either of those at around 50 PSI.

Returnless? I see inlet (left), outlet (bottom), and vac reference (right)

Post a video of the noise. I had a noise issue with my Aeromotive which was definitely cavitation. It took a revisit of all pressure side fitting choices to cure.

It appears the FPR is on the return side (after) the rails. This is an ideal setup. You only need the three port regulator if you are deadheading to the rails.

Attachment 72056

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Originally Posted by Josh

It appears the FPR is on the return side (after) the rails. This is an ideal setup. You only need the three port regulator if you are deadheading to the rails.

Attachment 72056

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That makes sense and is a great way to regulate pressure.

The original post said "Is the noise caused by the fact that it is a return less system?" That's what made me think "how".

This is what mine sounded like after a 3 hour summer highway drive. Engine is off, this is just the fuel pump running.
Adding cool fuel immediately eliminated the noise.

I added insulation between the coolant pipes and fuel tank, then removed a bunch of angle fittings in the feed line to reduce friction losses. That seemed to do the trick.

https://www.youtube.com/watch?v=O97W7CLuAAg

I'll get a video when I can. Returnless: typo. Regulator is on the return side as the photo shows.
Even during some cooler evenings here (55-65F) it still whines.

Difficult to hear over the engine. The whining is much louder inside the car even with the latest addition of a rubber isolator on the FPR mount.
This was at ~80F with 45% humidity with engine at operating temp after a drive.

https://drive.google.com/file/d/1Dqe...usp=drive_link

You may have to put rubber clips on the hard return line so it does not resonate with the chassis.

The permissions aren't set correctly on your video.

Since your EFI converted just turn on the fuel pump with engine off and make your recording, should be a simple switch in your tuning software.

I used to have that some one on my car. But it started to get less and less pressure. but the engine always ran fine. i rebuilt it a few time, but it still happened. i have a cheep china one on there now , it doing the same thing but runs fine.

I think I hear more of a squeal sound?

You can possibly rule in/out thermal problems by adding fresh fuel when the noise starts.

Is your vac reference common to both banks or just one one side of the motor?
If you pinch the vac line during idling does the sound change?

In car video at idle: https://drive.google.com/file/d/1Ytw...ew?usp=sharing

Driver side bank - no change when vacuum line pinched. Fresh full fuel or 1/4 tank does not effect sound. After a couple hour drive the other day it quieted down some.
Attachment 72071

Are you sure this isn't fuel pump noise?

The diaphragm in the regulator could make a great transducer.

All is quiet in the fuel tank area - even with trunk cover removed.

Sounds like its still the regulator then? If you search broadly for noisy/whining bypass regulators that seems to be the most common result.

My regulator is removed and just sitting around if you'd like to swap in a slightly different style. I won't be using it in my swap.
https://aeromotiveinc.com/products/a...tyle-regulator

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Originally Posted by FABombjoy

Sounds like its still the regulator then? If you search broadly for noisy/whining bypass regulators that seems to be the most common result.

My regulator is removed and just sitting around if you'd like to swap in a slightly different style. I won't be using it in my swap.
https://aeromotiveinc.com/products/a...tyle-regulator

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That would be nice. Is such a thing as an undersized FPR? We're not talking a 1000hp race car here.
As mentioned I replaced the diaphragm with no positive result. The old one was in good shape.

Could be oversized?

If you search more broadly for noisy bypass-type regulators, the issue of squeal/whine and proper sizing comes up frequently.

Aeromotive says 1000HP for the unit you have which would be oversized LOL. Unfortunately NVH is not typically a design constraint for race car parts. I'm moving the regulator directly to the fuel rail on my next build, in part to avoid the noise potential.

Noise completely disappeared on a few separate long drives recently and always goes away 95+% while cruising. I'll try some adjustment or be on the lookout for an alternate brand FPR.

Has anyone mounted a FPR directly to their fuel rails? Would this increase the probability of noise due to being closer to a heat source?

Not sure if it applies or matters since I'm using a non-adjustable, but I kept mine in the stock location the B280F engine had, right on top of the intake manifold, even though the engine is the eagle 3.0. Zero noise or problems.

https://dmctalk.org/attachment.php?a...7&d=1779801060

Researched more info on the injectors with a corrected P/N and found data to help. Suggested idle for them is ~43.5PSI on a modern VW engine and the car was set at 40-42PSI since the conversion. Combined with the modern Delphi pump the flow rate is more than needed for a PRV and bumping idle pressure to 50psi reduced whining and smoothed idle a bit. Will adjust fuel tables as needed and see how it goes.

Injectors: BOSCH 028015702

Idle PSI turned up and noise has diminished under most conditions. Good news is that with the size of these injectors I'll never run out fuel.