car hiccups and stalls

[Bob]

I am new to the list.

I have a 1970 American 280 SL with 93,000 miles.

Recently I have a real problem:  the car starts fine, idles fine, and drives out of the driveway fine.   After a few minutes it begins to hiccup, lurch, semi-die, feels like the accelerator is being floored, and then (at a light) will die suddenly.   

The local MB dealer's oldest mechanic cannot figure out what is wrong, and Gernold from SL-Tech in Maine (who recently worked on the car) can't figure it out either.   The emission control system has been removed, and timing set to this state.

Any suggestions

Bob Rudolph
Wyomissing, PA 19610

[280SE Guy]

Is your car red with black interior that has been sitting at the local Mercedes dealer on Lancaster Ave. for the last month or so? I would suggest taking your car to Red Kieffer's in Douglasville 610-326-5754. Talk to Jim (Sr.) Kieffer. They have the experience with the older models as they were an authorized Mercedes service center from 1967 through 1995. They can arrange for flatbed service if your car is not driveable.

Let us know how you make out.

[rogerh113]

I had a problem with similar symptoms - started up fine, great drive partway to town, then the car just died when I took my foot off the gas.  Got it started again and kept the revs UP, and managed to get it home.  Took a while, but it turned out that my fuel pump was failing.  Go figure, reved ok but wouldn't idle??  Put in a new (rebuilt) fuel pump and all has been well with the car. 

Your problem could be fuel starvation.  How long since you changed your fuel filter??  The fuel feed line can be detached at the engine support (near the fuel filter) and the flow rate checked (earlier posts talk about this).  This will not indicate an intermittent fuel pump or clogged fuel filter, but it is a starting point for a weak fuel pump, clogged flower pot in the gas tank, and/or a problem with the fuel lines.

Good luck -- Roger

[ja17]

Hello,

Yes, I agree, fuel starvation would be what I would look into first.
The fuel tanks can become clogged also. If you remove the fuel sending unit in the trunk, the fuel tank can be inspected inside without removing the tank.   If the tank has sediment in the bottom, you will need to have it cleaned out. Keep us up to date.

[BaronYoungman]

I agree with the fuel tank....just a little rust will clog everything and will only effect (or is it affect) the fuel when under pressure.
Bob

[Hargus]

Ditto fuel pump or other cause of fuel starvation. I have had my 1966 230SL for 21 years. It must have had the fuel pump replaced once before that as it has the newer style "short" pump. I was considering rebuilding it with excellent advice from Geroge Des (thanks again George!) who has a very detailed set of instructions in the tech manual. Unfortunately my armature is shot and rather then spend a whole lot of time running down one or getting it repaired I just ordered a new one. The best deals appear to be Adsit or Benz Dr. I wasn't certain if there would be additional customs duty from Benz Dr. (He's in Canada) so I want with Adsit. (Hasn't come yet but they are on the supplier's list.) Adsit has it for $538 + shipping - plus more for the new bracket if you are replacing the older "tall" style. List price is in the $900 range so about $560 delivered seems... reasonable.

I had symptoms similar to yours. It ran fine for a few miles but when I got on the freeway it was starving for fuel. No junk in the tank or pump, just a badly worn armature. Weird as it never had a problem until then, and it just failed all at once. I knew it was the pump as after the tow truck driver unloaded it it ran fine to get into the garage. Usually they fail to start a few times before failing while driving.

In my youth I was a mechanic in an independent Benz garage so the behavior was familiar to me. Here's a tip - turn on the key without starting and check if you can hear the pump running (it's just forward of the tank on the driver's side). If not put your hand on it and feel for running vibrations. If not tap lightly with a rubber hammer and see if that starts it running. If so it's the pump. If it's running but performing poorly then probably a restriction of some sort, gunk in the tank or pump or a clogged filter.