I like to address a common issue on the VW. Interfere causes the gauge to flicker sometimes mistaken as real flow.
I like to make one modification on the green harness (user port). Slice open the vinyl sheath as close to the RJ12 connector as possible. Pick out the white wire and cut it in half.
This wire is not needed on your setup. It sometimes picks up interference from the red and green wire of the Di fuel injector. Let me know how you get on. A picture if possible.
What type of tank do you use? Do you use our tank adaptor that comes with the kit? It has a similar seal as the water level sensor. If it was over tighten it will develop a split in the long term. A replacement
gasket is needed.
Shipping by post is very reasonable.