Fuel Pump Buzz

[Mayuri Krab]

Hi guys

I have a Bosch 040 fuel pump installed about 2.5 years ago after my stock one died.

I know (from reading here) that the Bosch units always buzz louder compared to stock, however last week while making several trips back & forth between different JB HiFi stores to collect my TV & A/V receiver stuff the car started to make a very loud buzz noise near the end of the day.

It was a 35 deg C day & I have being using A/C all day long, the noise is the same type of buzz noise the fuel pump makes normally & comes from the same location (near the fuel tank) but MUCH more louder, that you can hear it very clearly when accelerating off or just cruising along at 60km/h. Normally the pump buzz noise can only be heard if you tap the accelerator in park/neutral & is standing outside the car.

It only makes this noise after extended period of driving so if I leave the car over night the buzz noise will go back to normal volume.

A local workshop checked the fuel pressure & said it was normal & they didn't find anything wrong with the pump but they also said while on their test drive the same noise didn't occur. I'm assuming because they didn't drive it for long enough (I drove close to 1 hour before the buzz got louder). Also the temperature these couple of days have gotten down from mid 30s down to mid 20s.

At this stage I'm suspecting that the pump could be over heating since both times it occurred was on a hot day & I was driving for extended period of time with A/C on max (oil & coolant temperature was normal though), but how would I go in fixing the issue if the pump was over heating?

Should I just get a new pump installed?

Any other suggestions are welcomed.

Trying to get this shit sorted before Christmas since I need to drive to Albany during that time (430km trip).

Thanks.

EDIT: Also as far as I can tell the car still drives & acts normal when the loud buzz occurs & I had about 1/2 tank of fuel while it occured so it wasn't low on fuel if that is of any use.

Edited December 7, 2011 by Mayuri Krab

[DVS JEZ]

Its very possibly the hot fuel. U can run a fuel cooler if u want to try.

Or take a spare fuel pump

[scotty nm35]

I have a similar issue after long drives in the heat. I was trying to think of ways to cool the fuel down like insulating the fuel rail and lines but I guess the easiest would be to fit a fuel cooler in the return line, if I can find room for it...

[Mayuri Krab]

So I went & got another fuel pump installed, took for a test drive & the noise didn't occur. But then again these couple of days have being relatively cool (mid 20s) compared to before.

Also noob question:

When you guys talk about fuel cooler, is it just one of those generic oil coolers or are there specific coolers designed for cooling petrol?

Since I can't find any specific ones for petrol on Just Jap website, can only see oil, transmission & FMIC.

[zebra]

ranges from stuff like this

to this

to fancy ice baths

[76GTR]

Hi, i would recommend checking the earth of the fuel pump circuit and supply voltage.