SL-Class (R129) 1990-2002: SL 280, SL 300, SL 320, SL 500, SL 600, SL 60 AMG

SL/R129: M120 power loss

Old Apr 8, 2023 | 09:42 AM
  #1  
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SL 600 R129
M120 power loss

Hey there,

I'm the owner of a 1995 SL 600 with distributor ignition, and I've been having some problems I can't trace.

The car has already had a cat delete, EGR delete, air pump delete, MAF and throttle bodies rewired, new EGAS module, K&N filters, Magnecor leads, and new distributors. After the repairs, the car ran just fine, and with plenty of power (only limited by the not very good gearbox).

One quirk during all this time is, when the fuel level dropped below half, the car would sputter and run rough. Fill it up, and everything's good again.

A while ago, I started noticing a loss of power, specially over 3000 rpm, and a strong fuel smell.
The fuel rail had developed a couple of leaks at the solder. After replacing the fuel rail, there are no more leaks, but the problem is still there.

It runs right up until 3000-3500 rpm, and then, it just dies off.
The only way to make it rev past that, is in second gear. Either in 3rd or 4th, it just runs out of power and can't rev past 4000, even at full throttle.

Any indications on what the problem might be? A dying fuel pump, or a clogged filter?

Any help would be appreciated

Thanks a lot



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Old Apr 9, 2023 | 10:14 PM
  #2  
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From: Lutz, FL
1997 MB SL600
Both the fuel pump and filter could be suspect, especially if you have never changed either.

I don't know if the 95 fuel rail is similar to the 97, but there is a filter in the rail too and every injector has a filter where the gas goes in.
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