Mercedes-Benz Forum banner

1 - 9 of 9 Posts

·
Registered
560 SL 1988
Joined
·
13 Posts
Discussion Starter #1
Any input re: Starting at times sounds like no gas is flowing to the carb (dry start/cranking). Had 2 new gas pumps installed a year ago due to leaks.
Where is the filter to check/clean, Best additives to try,etc??
Thanks Robert
 

·
Registered
1998 C280; 1987 560SL
Joined
·
471 Posts
Filter is behind rear wheel on passenger side (along with fuel pumps). Does the car run okay after it starts? Does it start better cold or hot?
 

·
R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
Joined
·
31,991 Posts
Same questions. Hot start? Cold start? Look in the EGv107 for a picture of the fuel pump package. It shows pump, filter, and accumulator layout. If you find one with one pump it is basically the same layout as two.

PS. No R/C107 has a carburetor.
 

·
Registered
560 SL 1988
Joined
·
13 Posts
Discussion Starter #4
Same questions. Hot start? Cold start? Look in the EGv107 for a picture of the fuel pump package. It shows pump, filter, and accumulator layout. If you find one with one pump it is basically the same layout as two.

PS. No R/C107 has a carburetor.
Thanks for both responses. Same for cold/ hot start. Car is always garaged in Los Angeles. Tried pumping gas pedal with no instant reaction..but it eventually starts.Is there a filter for each pump?
 

·
R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
Joined
·
31,991 Posts
One filter. Couple of pics. First is not a Mercedes but shows the parts. Pumps, filter,, accumulator

Dual pump parts.jpg

Second is 560SL but the accumulator is not shown.

560SL fuel filter 007.jpg
 

·
Registered
1986 560SL 1986 420 SEL
Joined
·
93 Posts
Your 560 is fuel injected with a KE Jetronic System. Do not pump the accelerator when starting the car.

Passing the smog test probably a good indication that your vacuum system is OK, but I would still check it. Spray brake cleaner around the engine (injectors, under the air intake, around all those black tubes). It engine speed increases you have a vacuum leak. This causes unwanted air into your engine and can cause hard starting.

Next,, you have a cold start valve located near the front of the motor next to the left, driver's side, valve cover. When you turn the key the fuel pump relay opens this valve to put in extra fuel to get car started. Do a search in the 107 forum and the 126 forum for lots of info on this.
Searching for general vacuum leaks is fairly straight forward. Testing the cold start valve is a little more involved and may require a multi meter test tool. A year ago I knew nothing about any of this. Been fun learning on this forum about how these cars work.
 

·
Registered
560 SL 1988
Joined
·
13 Posts
Discussion Starter #8
Your 560 is fuel injected with a KE Jetronic System. Do not pump the accelerator when starting the car.

Passing the smog test probably a good indication that your vacuum system is OK, but I would still check it. Spray brake cleaner around the engine (injectors, under the air intake, around all those black tubes). It engine speed increases you have a vacuum leak. This causes unwanted air into your engine and can cause hard starting.

Next,, you have a cold start valve located near the front of the motor next to the left, driver's side, valve cover. When you turn the key the fuel pump relay opens this valve to put in extra fuel to get car started. Do a search in the 107 forum and the 126 forum for lots of info on this.
Searching for general vacuum leaks is fairly straight forward. Testing the cold start valve is a little more involved and may require a multi meter test tool. A year ago I knew nothing about any of this. Been fun learning on this forum about how these cars work.
Thanks for the in-depth input. You sound like a certified MB mechanic!! (and probably know more than some MB repair locations here!). Cheers
 

·
Registered
1987 560SL, 2000 Kawasaki W650
Joined
·
969 Posts
I had an intermittent no-start problem for a while, the fuel pump relay had gone bad. It’s a black box located behind the glovebox. There are two transistors in that unit known to get fried. My first fix was to pull out the relay unit, give it a whack on the dash and then plug it back in. I replaced the fuel pumps and I got a used replacement and that fixed it completely.

When you turn the key to the RUN position before starting, you should hear the fuel pumps in the rear run for a moment as they get the fuel line pressurized. Like a “Wshhhht“ kind of sound.

I think what happens sometimes is that as the fuel pumps go bad, they draw more current, eventually enough to foul up the FPR, like blowing a fuse. One of these days I’m going to put a fuse in line between the fuel pumps and the FPR, to protect the FPR if the fuel pumps start to wear out and draw excessive current. Your old pumps may have shortened that unit’s life expectancy as mine was.
 
1 - 9 of 9 Posts
Top