I’m following the fuel line…..comes out of the tank, into a fuel/water separator filter, out of the filter up between the starboard exhaust manifold and intake, and into the block between the dipstick and oil filler.  
 

I only see 3 electrical connections, 2 on top of the fuel/water separator, and one on top of the in tank fuel pump.  The 2 on the fuel water separator are for the Water in Fuel, and Feed pressure sensor.  Only know this from unplugging and plugging back in and getting 2 new inactive faults.

The plug I see one connection left, it is on the in tank pump but I have to remove the floor to get to it.

I don’t see any more obvious fuel delivery parts/connections once the fuel line leaves the filter and goes up to the block between the intake and exhaust manifold valley?

14 hours ago, CaptainMorgan said:

i'm a couple weeks from needing to change my recall-affected M6 oil...where are folks getting their Mobil 1 full synthetic 0W-40 dexos R these days?  

i see the "Supercar" option in a few stores for like $13/quart, but i thought there was supposed to be a cheaper non-supercar option?  

I thought it was later clarified we can use the European 0w40 which can be found often in the $25 range for 5 quarts 

https://www.amazon.com/dp/B00HG76A9A?lv=shuf&channelId=500&plpRedirect=mhFallback

I still have my free oil change from the dealer to use this fall for winterization so will ask what my dealer has to say then, but pretty sure they are no longer using the super car oil that my z06 takes and is pricey. 

Before you dive in there to find the sender, answer @UWSkier's question.  It could be the gauge, the sender, or in between.  My vote is on the gauge ground wire, which is probably connected to the engine head or transmission bell.

I think the IMV should be mounted directly on the high pressure fuel pump, under the intake manifold.  No surprise that the dealer didn't want to fool with it.

I agree that you seem to have an intermittent connection.  I would try to locate the IMV wires as they emerge from the intake manifold and trace them to the engine harness and then back to the ECM.  Break every connection you can find along that path and carefully inspect for bent or loose contacts.  It is common enough to find a pushed pin or socket that needs to be reseated.  The problem could also be a bad crimp, so a gentle pull on each wire coming out of each connector isn't a terrible idea.  If you end up with a connectorless wire in your hand, maybe you have found something!

Keep in mind that the poor connection may be under the manifold.  Avoid probing sockets by jamming your meter probe into them, which will only make things worse by spreading the contacts.

Let us know how it goes!

Still evolution from what I’ve gathered, but if it just needs some repairs take it to a local shop to patch up.