69 280 SL

I have a 1969 280SL. I had my local MB dealer replace the Fuel Injection pump as the old one was not working. Last fall it was in several times (after installation) because it either ran rough at idle or if that was fixed it had no power in the higher rpm's. The mechanic said he tuned it to the specified CO level but then it didn't get enough fuel at highway speeds. IT starts cutting out from fuel starvation. He is frustrated and so am I. I think he knows what he is doing as he is the guru for the old cars there. But he can't seem to solve the problem and get the car to run right. I do have an old Haynes book for my car and it talks about the full load screw and the lower partial load range screws. Are these part of my problem? I really don't know if he is adjusting them or not. Any suggestions would be appreciated. I hve had it running good on the high end but then the idle will be rough and sometimes backfire. HELP.

PS Should I try someone outside the dealer? The problem is they installed the injection pump and if I go somewhere else they may quit trying to fix it.

Nektopoli

You might start by looking at the fuel filter.

NP

69 280 SL

I have replaced the fuel filter and had the fuel system pressure checked. What can go wrong in the air side of the equation? With a car this old can the air intake be off somehow resulting in an incorrect mixture? The timing has been checked to including the runout of the distributor to make sure it wasn't loose.

Thanks again for any suggestions as I am at a loss.

MARK CUMMINS

I Would Post This On Mercedesshop.com

Yes It Takes a Special Tech to Work and Dial in the Mechanical Fuel Injection.As Most Dealer techs Only know late Cars and Would be Lost On Your Mechanical Injected SL. .You said the Pump has been rebuilt...by Who?Mercedes or Outside source..The Pumps can have several problems..Sticking rack,worn cam,and defective thermostat.Also The Factory C/O setting May be to Lean!. What Is The Condition of the Engine? Timing/Compression/Leakdown? all for running problems you are talking about!
I Have Worked on Several Mechanical Injected Porsches..And It Takes The Correct tools and Lots of Practice of working on the Injection to make it run.But When They are Done They Run great!.

Good Luck Mark

godrivenow

I had bad spark plugs that acted the same way.
Pressure is easy to check and eliminate.
Fuel injection can be a nightmare on 280sl"s
Good luck!

JettaRed

iTrader: (1)

Um, you do realize this thread started over 20 years ago? Right?