1967 230SL Fuel Delivery Problems

[Robert K. Marcho]

I am attempting to help my widowed next-door-neighbor with her 1967 230SL roadster. Her husband was the 2nd owner and drove it for a number of years, unfortunately after a long battle of many years, he passed away last year.

She would like to get the roadster running to either sell it or give it to one of her sons/sons-in-law and has asked my help. Among many problems -- teaching 177 freshmen, being in the middle of winter prep/engine rebuild on my 300ZX SCCA race car, and my 1960 Austin-Healey vintage racer -- I have little time to devote to diagnosing the problems, and yet I truly want to help her out.

I must add I did get it running about 4 years ago (after it had been sitting for many years) with little difficulty, even though I diagnosed a miss as a faulty/clogged injector.

In the meantime the car has been sitting unused for 4 years. The fuel tank was completely dry when I pushed it to my house, and after putting in 5 gallons of fuel I can only get fuel delivery to the fuel block (forgive my ignorance of terms, I don't have a factory manual), the piece where the fuel injector lines all sprout from before going to the cylinder heads. I can get it to "run" (a term I use advisedly) on starting fluid, so I know it is getting spark. But a check of the spark plugs -- and the inability to run on anything other than starting fluid -- shows no fuel being delivered.

The only factory manual I have is for a 1969 280SE/etc I owned and rebuilt many years back. Since it was carbureted with dual Zeniths, and the manual I have only covers 1968 and later models, I have a few questions:

1. The factory manual I have also covers 1968 and later 280SL, etc. Is there any significant mechanical design changes --apart from engine displacement -- from 1967 230SL to the 1968 and later 280SL?

2. Are there any on-line manuals available for this car? Can you point me to them?

3. Any suggestions on what I should look at next?

All help would be appreciated. If at all possible, I would appreciate replies directly to my e-mail -- Marchor@acu.edu

Thanks,

Bob

[Benz Dr.]

Sounds like the injection pump - probably a stuck rack or injection elements. This is fixable in most cases but the pump will need to be removed for a rebuild.
 Do a compression test first along with a bit of oil in the cylinders to aid compression.

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org
  1 877 661 6061

[rwmastel]

Group,

Bob (Marco Polo) is located in Abilene, TX.  Any oter Texas member near there?

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[rwmastel]

Bob,

Manuals: http://www.sl113.org/publications.asp

Here's a very well respected specialist in these cars that happens to be in Texas:
S&S Imports
Attn: Will Samples
3303 Wendy Lane
Dallas TX 75124
214-826-5977

If you get to the end of your time or skills and need professional help, you could have the car towed to him on a flat bed.

The 280SL drivetrain is basically the same as the 230SL.  The 280SL had more emissions control and fuel economy gizmos.

The part you mention is the mechanical fuel injection pump.  The electric pump near the fuel tank pumps fuel to the injection pump.  This pump has 6 plungers, each one pushing fuel to each of the engine cylinders (and the CSV).  Any excess full the injection pump does not use is returned to the fuel tank.

To prove that you are on the right track, loosen the six fuel injection lines at the fuel injectors and see if fuel is getting that far.  Don't forget the 7th fuel line going to the CSV (Cold Start Valve) on the intake manifold.  If it's not getting there, then you have a stuck injection pump.  Let us know.

As usual Dan's right, a compression test is always useful diagnostic information.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[ja17]

Hello Marco,
Make sure the electric fuel pump in the back is running. You will hear it whine. If fuel is at the injection pump, under pressure, as Rodd mentioned crack loose an injector line at the head to see if fuel is making it that far. If the entire system was dry it may take some cranking to re-prime all the lines. Crank the engine with the accelerator pedal all the way to the floor until fuel shows up at the injectors.

If the fuel never arrives at the injectors, as Dan has mentioned, the rack in the injection pump can be stuck. For a diagnosis on this check back in with us.

You probably cannot find a better source of information than this list, however manuals can be good ref. material.

Keep us up to date.

Joe Alexander
Blacklick, Ohio