Hello,
I have a 1994 f350, 460 cu in, EFI, gasoline/propane

On gasoline, it runs rich, black smoke and very rough idle as well as rough operation while driving.

I changed plugs, wires, cap, rotor, fuel pump relay. Six months ago, changed fuel pump & fuel filter.

It scanned as follows:
koeo: 556-fuel pump relay primary ckt
koer: 173-ego not switching, rich exhaust-bank 1
cont. mem: 126-map or baro snsr out of range
173-(as above)
212-no tach input to processor-spout
334-egr(evp) voltage above closed limit
542-fuel pump ckt open-eca to grnd

then, cleared codes and got 556, 212 & 542 again.

Data stream mentioned: SFTRIM-in closed loop (-23%), after a few minutes it switches to open loop (+11%) and hangs there.

Today, I checked fuel pressure and got 80lbs with key on, while engine running, it bounced rigorously between 80-85lbs.

I haven't run propane in 6 months, decided to throw $20 in tank, came home & switched it over. On propane, it runs like a charm.

Also, no fuel coming out from top of FPR or hose, when disconnected, with engine running.

Is my next step to replace the Fuel Pressure Regulator? I have had a quick "once over" the fuel lines and don't see any kinks/issues...

Thanks for your consideration guys!