Mercedes: diagnostic, merecedes benz, fill tank

Question
QUESTION: I have a 1972 Merecedes Benz 280 se or sel not sure title says sel, car se v8 4.5 lt with fuel injection. It ran great until this area was hit by flooding and we had to drive it in the flood water. the fill tank opening is under license plate and the cap was the original and at the time didn't think about it but some water got in gas tank, eventually the back firing ceased .but at the same time the water pump started to go out and were unable to deal with so it was shooting water every where under the hood. the water shorted out the starter so we started there,replaced it then next replaced water pump.  after the replacement of that the car wouldn't hardly drive it has no power wont go over 30 miles an hr and acts like the timings off we've adjusted the timing and sounds good until a loads put on it and then its back to sounding like the timings off. some times when u first get in it, it would start out like it was going to drive and run great but it wouldn't last a block or two and back to no power. We took it in for a diagnostic and replaced everything they had on the list: which includes distributor cap, wires, spark plugs,rotor,points,fuel filter as well as the starter and water pump. Please If u have any suggestions it would be greatly appreciated .  thank desperate to revive my classic

ANSWER: Is the vehicle just not producing power or is it also still skipping. If you have a timing belt,it could have also jumped timing during the backfiring. If you had to move the distributor in the block to increase the power, then you may have jumped a tooth or two on the gear. I had this happen on a Dodge engine.
It ran but did not have enough advance to have much power. By luck I discovered it and replace the chain before it moved another gear and swallowed valves.

Also, if the vehicle has a catalytic converter it may be trashed. Back pressure will cause the symptoms you describe.  
Have you replaced the fuel filters. If it has an electric pump, it my not be providing sufficient fuel pressure because of clogged filters.
Hope this helps. Let me know what you discover.
Rob


---------- FOLLOW-UP ----------

QUESTION: Hi Rob, Thank you for your help, my follow up Question is, I have checked to make sure # 1 cylinder was at top dead center, also checking rotor placement and fly wheel, would this rule out jump in timing chain? I will check the catalytic coverter. I have replaced the fuel filter and it was very bad. Could a bad vacumm advance cause this? and can you think of anything else i might check?  thank you for your assistance. John

Answer
John,
If the rotor position relative to Top Dead Center is correct, then you are probably OK regarding the timing chain.
Yes a bad vacuum advance could cause the problem. Also, if you have a broken or loose vacuum hose that would not allow the advance to work. It may have happened during the water pump replacement.
If you have one of those hand operated vacuum tools used for that purpose, hook it up to a short hose and see if it pulls the mechanical disk inside the distributor.

Vehicles this age can have rubber hose leaks that are not visible to the eye because of dry rot. Very fine crack develop where the hose is attached to servos etc.
Good Luck
Rob