I have a 90 740GL with a really bodged together Regina fuel system. It has a Bosch pump added under the car, and the high-pressure fuel hose from tank to rail has been replaced with some low-pressure tubing. The plumbing is nightmare-fuel, honestly. There's a threaded fitting involved that seems like it might be intended to connect to the check valve... if it has a check valve?

I'm not sure what a correct Regina fuel filter setup looks like under the car. Can someone show me an example? How does the fuel line from the tank attach to the filter and does it have a check valve? I can just cut a piece off of the fuel line, but does anyone know the correct ID? 5/16"?


On an unrelated note, #3 spark plug was *horribly* cross-threaded like I've never seen before. Like so far off that the plug was 30 degrees off from where it should be and only 3 turns to remove it. I used a thread chaser to try to fix the threads (oil threads, go in a little, out, clean the threads thoroughly, repeat...) and it seemed to work, but we will see once it gets nice and hot if it shoots the plug out like a champagne cork when you shake the bottle.

Anyway - I think the Regina system is supposed to use larger plug gaps than Bosch (.028in.), but can't find that documented anywhere. Did I imagine that?