2002 S40 whinning noise from under hood

2002S4019T · Post by **2002S4019T** » 05 Jul 2014, 19:09

Hello, hoping I can get some helpful info until the manual I ordered arrives. There is a high pitched whine coming from a little gadget that is attached to the firewall under the fuse box on the drivers side. It also gets very hot. The frequency is the same as the sound that last a few seconds after first turning the key on. Is that a fuel pump? Any advise is very much appreciated.
I originally put this on the general questions forum by mistake so I will delete that now. Someone did advise me that it is probably the "forward fuel pump".

shanegtr · Post by **shanegtr** » 05 Jul 2014, 20:19

Im fairly sure it is some type of fuel pump. I pulled one out of my parts car from the location that matches the description you just gave. Didnt sound like you mentioned however - sounded more like the typical electric fuel pump if you know what I mean

2002S4019T · Post by **2002S4019T** » 07 Jul 2014, 12:55

I put a sound-scope on the gadget which I now believe is the forward fuel pump and it is making a whining sound. Whether or not that is bad is hard say. I don't recall it making the noise before but maybe I just never noticed it. The car is running fine.

Post by **jimmy57** » 07 Jul 2014, 13:38

Sounds like the vacuum pump for the brake booster.
It is silver and 2 1/2 in diamter and 5 or a little more inches tall and has a black hard line attached to it.
The switch for it is in the hard line if you follow it and if the noise stops when unplugged then it is the switch or you have a major leak in the hose or booster. If brake pedal effort is normal then booster can likely be struck from the list.
Switch failure is the most common cause. The switch can pop apart.

2002S4019T · Post by **2002S4019T** » 09 Jul 2014, 15:43

the brakes seem to be working fine and the noise has stopped, for now anyway, but thanks for mentioning that, I will be cognoscente of it in the future.

2002S4019T · Post by **2002S4019T** » 16 Jul 2014, 13:00

After further evaluation I do believe the problem was the brake booster, thank you Jimmy. Since the whining has stopped the brakes do work fine except first thing after start up and during emergency stops they require a lot of pressure and are very soft.