Aloha all,

Newbie here (Captain Dean) just signed on for the first time.

I've got a classic 1973 450SL that has been sitting for two years. I'm trying to get it started again but the fuel pump is not running - no voltage to the pump connections. It used to run before I parked it.

I've recently emptied the tank of oldgasoline and put in 5 gallons of fresh gasoline.

When I turn the key I hear a relay click 1/2 second after turning the key to "Run". Still, the pump does not run nor does any gasoline arrive at the engine.

Are there any fuel interlocks I should check?

Aloha, Dean.

 

Greetings Cap. Dean, You're likethefourth person I know with a fuel pump problem on a R107. I ended up replacing my fuel pump twice on mine because the dousche bags at Loeber Mercedes decided to give me one for the carbureted model. But enough about me. From what it sounds like, your fuel pump relay is dead. I've read a bit about it and it seems to be a problem for a few people. A relay will run you about $130.00 to $140.00. On the other hand, if it is your fuel pump, that will run you (and I know this from personal experiences), $600.00 from a dealership. So, short version, It's probably your relay, but I would wait for a few more posts to say the same.

 

Aloha Peter and group,

Thanks for the reply and suggestion. Instead of spending $145, I swapped the relay below (same P/N) with relay #1 (Electric Fuel Pump) but still did not see any pump movement. The fuses checked good too.

Are there any interlocks I should examine? A message I once read said "...his '76 Mercedes engine would stop when the fuel got to a certain level in the tank..." Does the '73 450 SL have any low fuel interlocks? Should I just put another 5 gallons in the tank and see what happens?

I've had the engine controller out (from the passenger side bulkhead) and examined it. No obvious faults. Is it sensitive to positioning, like detecting a rollover? Is there a rollover reset switch?

The two manuals I have don't give a lot of detail on the fuel system. There must be a fuel [pressure?] sensor that controls the fuel pump relay?

Is there a place on-line to get a wiring diagram?

Aloha, Dean.

 

You are fortunate to have a classic Merc,well the problem may be on the Mercedes Benz diesel injector. On the other hand,your fuel pump relay is dead. I had read a few pages about it and it seems to be a problem for few people.A good check up from your trusty mechanic is also a good idea.

 

Aloha RedMansioner, and others,

Thanks for the reminder about being lucky to have a classic Mercedes. I think that is why I'm continuing to strive to get it running. When my free-time comes back, I'll pull the fuel pump and run it backwards in diesel fuel. I suspect another fellah is correct about it locking up on varnish from old fuel. Find out in a week or so.

Aloha, Dean.

 

has it ever occured to anyone that perhaps the fuel pump relay is not working? I am having the same issue with my fathers 1973 450 sel and i am looking for the fuel pump relay. I cannot find it and it is driving me crazy!!!!