Volks, This series of questions involves for me a Diesel TDI engine, but the same principals are involved with a fuel injected gasoline engine, so hence the cross-posting.

We are going to be starting on a TDI conversion that I want to "kick up a notch" as far as instrumentation goes. The eight function gauge that I have installed into our TriStar has the ability to use a few flow meter so that I can view the instantaneous amount of fuel being consumed by the engine. The problem is I can't see how to connect the fuel meter so that I can get an accurate reading. The meter is basically a little "box" with a fuel input and output on it and it will give an electronic "pulse" per every unit of fuel that flows trough it. The gauge attached to it counts the pulses and determines fuel flow from the amount of pulses over time. Now as we all know, modern Diesel and Fuel Injected gasoline engines has an input from the fuel tank and any fuel it doesn't use goes back to the tank. As a result, the line from the tank to the engine doesn't show the real fuel consumption as there is always fuel going back to the tank. A the to and from lines are never a constant difference ratio, the only thing I can see doing is loop the engine's fuel output into the input of the fuel pump instead of back into the fuel tank. The main reason why we dump fuel back into the tank is it makes the system self bleeding system by removing air bubbles. Air bubbles are bad for fuel pumps. The other reason for fuel being returned to the tank, especially in a Diesel is it cools the fuel off as the TDI will give less power if the fuel is too hot - hence the fuel coolers on the pump düse engines. So basically I am wondering if there is any such thing as a "bubble trap" out there to prevent air bubbles from being trapped in the system and if there is a way that I am missing about installing fuel metering devices?

For a picture of our prototype engine monitoring gauge see:

http://www.fastforward.ca/gallery/1005instrumentpod.jpg

Cheers!

David Marshall Fast Forward Automotive Inc. 4356 Quesnel-Hixon Road Quesnel BC Canada V2J 6Z3 Internet: http://www.fastforward.ca Email: sales@fastforward.ca

- Engine Conversions and Accessories for classic water-cooled Volkswagens - Electrical harness fabrication and customization