Fuel problem '73 280SEL

[ggaz]

I recently removed the fuel tank from my 73 280sel 4.5 efi- Had it hot tanked & preasure tested, dried it out got it back in the vehicle within a week & put 5 gals. fresh gas in it. Car started but idled very rough. Did some minor tuning noted I couldn't get idle above 500 with idle mix screw-stopped engine. It would turn but not start again. Checked for spark. There is fuel getting to the ring but when return hose is disconnected after ring, I note that there is no fuel returning to the tank with ignition switched on and fuel pump (new) running.

I would appreciate any suggestions on how to proceed from here very much. Thank you.

[psfred]

Fuel filter plugged, most likely if not changed with the new pump.

Otherwise, you are going to have to check for damage/clogging of the in tank screen -- this is the 24mm hex "bolt" in the bottom middle of the tank, and should have been removed when the tank was cleaned (not necessarily your fault!) since it has a brass screen.

I'd check, carefully, for fuel delivery -- with the fuel pump jumpered and running, you must get a liter of fuel in 30 sec at the return line. If not, you have a stoppage somewhere and you will have to find it. A smashed steel line, a bad rubber line acting as a one-way valve, etc. Very unlikely to be a bad pressure regulator, but that isn't impossible -- in that case, it will run WAY rich, as in black smoke pouring out the tailpipe from excess fuel pressure.

Peter

[autozen]

Why on earth did you hot tank it? Not only do MB tanks have special coatings to prevent rust, they have plastic parts at the bottom to do certain functions. I wonder how melted they are.

Peter