TheSamba.com :: View topic - cabriolet 93- Humming sound in main fuel pump

Sat Jul 22, 2006 3:25 am

I have just changed the two fuel pumps and the fuel filter on my digifant convertible 1800cc because they did so much noise. But the noise still on the principal pump. I know that several owners of VW of these years had the same problem. A solution?

Thanks for your help!

Sat Jul 22, 2006 9:24 am

You said you replaced both pumps. When the main pump makes noise it's usually because it's working too hard. So I'd make sure there are no restrictions keeping fuel from getting from the transfer (in-tank) pump to the main pump under the car. The transfer pump is supposed to deliver about 13 ounces of fuel in 10 seconds. I'd verify that both at the outlet above the fuel tank, then down where the line connects to the fuel pump assembly underneath. Restrictions elswhere in the system can cause problems too - make sure the fuel pressure is being regulated properly at the engine and the return line from the FI to the tank isn't restricted.
-Andy

Sat Jul 22, 2006 10:44 am

Thanks Andy for the tips! Before, I had noise (humming fuel pump) when the engine became hot but now, the pump makes especially noise when I apply the brakes or I accelerate. Silly thing [-(