As per the usual, I have good news and bad news. Luckily this time around the news is more good than bad.
As of last update I was desperately trying to get my dumpster fire’s tail lights working I assumed the problem was in the right-side cluster connector as that cluster is slave to the left and I was reading voltage at the connector. I bypassed the connector by shooting self-tapping screws into the “traces”. Feels a little barbaric, but I couldn’t find spade connectors the right shape and size to fit onto the connector itself.
Long story short on that, it turns out the problem was with the jumpering on the drivers side connector so I just bypassed the whole damn thing. I also swapped most of the incandescents for LEDs to avoid having to deal with the warped tail light reflectors.
Ok next up was the fuel distributor… again. This time during tear down I removed the brass fittings before flushing. Upon pulling the fuel pressure regulator (again) I noticed some odd scuffing on the plunger. I’d seen it before, but remembering that this system is very finicky, I went ahead and polished it with 1000 and then 2000 wet-or-dry sandpaper.
Everything buttoned back up, I jumpered the fuel pump relay and… Christ on a cracker my pressures were still wrong.
At this point I resorted to good old pen and paper troubleshooting.
Knowns: Control pressure and line pressure were the same; warm up regulator proven good; fuel flow good; fuel (likely) good enough; I have flow on my control pressure return line (which shouldn’t be possible).
Literally the only scenario that makes sense here is a clogged fuel return line. While I’ve checked the return flow out of the distributor (adequate) I’ve never confirmed the flow into the tank.
I ended up disconnecting the control pressure return line at the warm-up regulator, effectively bypassing the return line and instead using my garage floor. Result! The control pressure dropped down to 35 PSI, which is more or less correct for a cold engine. This means that either the problem lies with the control pressure return line, or the return to tank line.
Oh yeah… and I sort of kinda missed my May 4th deadline. Oops. Guess I am paying penalties!