In doing a little work on fuel filters and pumps on both my '85 and '87 Vanagons, I'm curious about something about the sizes of the hoses and the "standard configuration."

The 1.9 engines, except California, came with the filter before the pump. 7mm line to the filter, 13mm? filter out to pump, 13mm inlet on pump, and back to 7mm out of pump to another connection and off to engine compartment. CA models and '86 and up had the following:

2.1 had no filter before the pump, 13mm inlet on pump, 7mm out to filter, 7mm in and out of filter and to connection and off to engine compartment. 

I read a post about a recall of '87 models (presumably affection others as well) about the filters before the pumps being susceptable to leaks and being replaced with straight hose. 

I see on my '87 with 2.1 and just the filter after the pump that there is a hose within a hose at the tank outlet, as the tank outlet would call for the 7mm hose, but the inlet to the pump is the larger size. Is this how they were sold? There would have to be something like this in order to step up from the smaller tank outlet to the larger pump inlet. 

The earlier models, if they still have the early filter, don't have this problem as the filter has an outlet larger than the inlet.

So what is normal here? Why wouldn't they all just have the same size lines from the tank back to the engine compart?

Ed in CT