Sound dampening - noisy fuel pumps

[Batbaruman]

So I got a Bosche 044 Fuel pump in the boot, it's super noisy! My exhaust is pretty damn loud and yet the fuel pump can be heard over this.

 

any ideas how to dampen that noise? it's wrapped in rubber where it's mounted and the mount is not vibrating so not resonating the noise any further, but the pump it self is bloody loud. be real interested to see what other people have.

 

here's a sound clip, not my own recording but close to what it sounds like. that high pitch noise is pretty hard to ignore and drives me nuts. if i play the music loud it can hide it, but sometimes i just like cruising with all the music off and enjoy the sounds of the car.

 

 

and pic of current setup in boot - single bosche 044 to anti surge tank.

 

 

[THUNDA]

Fark that would drive me insane! might need to build some sort of box around it ? maybe some sound dampening stuff, havnt heard a pump even close to that loud before

[pedro]

Is it resonating on the mounting plate ?

Try dismounting it and see if it is quieter and maybe sit it on a high density foam pad..

[Batbaruman]

it does drive me insane lol! i like the idea of some sort of box and have seen some examples online but haven't heard much of their dampening qualities.  i have this suspicion that if it's not done quite right, it'll end up acting like an amplifier haha. it would also probably be illegal and not too safe given that electrical cable is right there and in case of fuel leak, the fuel will pool up rather than drain away as per LVV requirement.

 

11 hours ago, pedro said:

Is it resonating on the mounting plate ?

Try dismounting it and see if it is quieter and maybe sit it on a high density foam pad..

 

nah but good thinking! i also thought it was that at first so i removed the mounting plate and just sat it on a cushion for a bit, tried grabbing it etc. to see if anything vibrating but it's coming from inside. was wondering if anyone on the forum has had this issue and how they may have tackled it? i'd be keen to try those sound dampening matts /whatever people use to reinforce the boot firewall but it's a large amount of $$ to drop if it doesn't work

[Jono24]

Mass stops sound transmission, if you created a box to sit over the fuel pump out of mdf/sheet metal  and externally lined it with mass loaded vinyl or equivalent (dynamat or a plumbing/HVAC sound lagging product like wavebar DBX), this would do wonders. The more weight to the acoustic enclosure the less noise that will transmit through the enclosure (this is a crude simplification).

 

I can't speak for the heat that might build up in such a box, does the pump need to be ventilated? You might have to make an offset ventilation path so that sound cannot follow a direct path out of the enclosure for ventilation, you would also want to internally line the box with an absorber (similar to the dacron used in sub boxes, HVAC duct lining would be ideal) to reduce the reverberant noise level generated and to regain some attenuation lost by putting a hole in the enclosure.

 

You could create a ply wood shield across the rear of the back seats and cover this in dynamat/wavebar DBX, this I would hazard a guess to be the simplest solution.