Running out of ideas to get my 280 up and running

[MBasile]

A couple of months ago I took possession of a 280SL that was in a barn for 3.5-4 years. However, it had a lot of work done to it and was running reliably when put into the barn. I did the usual fluids and filters before trying to start it for the first time as well as draining the fuel and adding fresh fuel. I did have to disassemble the fuel pump at the rear to clean it out and get it unstuck. After that the car started up and idled for about 20 seconds and then died, my buddy and I both feel that the idle sounded normal for a car of its age. Upon the second starting attempt it fired up but them immediately died.

I've checked to make sure that the CSV is not leaking from the port on the side, and that the WRD is not stuck. After checking both of those I started the car again and gave it some gas until the temp was at 180. At that point it idled fine for about 5 minutes, and then died. It took some effort to get it started again, but it finally turned over and went out on the road for 3/4 of a mile, until I stopped to do a 3-point turn to get back home. As soon as I stopped the engine died and would not fire up again, not even for half of a second. This was all while the car had the smaller battery from my Subaru in it, as the previous battery was toast.

Today I put in a proper Bosch Platinum battery and tested the alternator with my non-super accurate Schumacher battery charger/tester and the alternator percentage jumped between 85% and 92%, finally resting at 92% for about 5-10 seconds before the engine died once more.

I have exhausted the possibilities I can think of from reading the technical manual here on this site, so I'm coming to you guys for help figuring out what to check next. The biggest problem is that the car is 45 minutes south of me, so I can't go tinker on it whenever I please, and while I understand the basics of cars, diagnosis is not my strong point.

[ja17]

Hello, 

Sounds like a fuel delivery problem. Check the main fuel filter. If it has dirt in it, then clean the fuel tank screen and the intake screen in the electric fuel pump.   Remove the fuel tank sending unit and check to see if the tank has an acumulation of rust and dirt.  You may need to clear the intake to the "Flower Pot" or add enough fuel so the tank fuel level will overflow the walls of the flower pot. 

[lurtch]

Here are couple of photos  of the fuel tank situation when I got my car. It car had been in a warehouse in Texas for five years.

I hope your is better off than mine was - - -.

Larry in CA

[mdsalemi]

MBasile,

Let me relate my final solutions to several years of problems such as you are acutely experiencing now:

1)  Check the integrity of the wiring to the fuel pump.  It starts at a "Y" from a cable bundle in the trunk, left side.  Two wires go through a grommet like thing in a hole in the trunk to the pump.

Checking the integrity means ensuring you have no breaks or splices from the point in the trunk, all the way down to the terminals on the fuel pump.  Then check the termination points on the wiring.

In my case, the restoration was done [incorrectly and improperly] by cutting these wires and splicing them.  The crimp splices lasted about 5 years or so before they started causing intermittent voltage drops.  Same thing happened at the terminals.

The solution was to replace the wiring from the bundle to the pump, and soldering all the connections, even the crimp connections.  Be aware you are working around gasoline.  Do not trust crimp connections and suspect them as a problem if you find any.

The location of the fuel pump is second to the horns in terms of living a "rough life".  You need all the voltage.  It is quite easy to get dirt, corrosion, and all sorts of nasty things happening underneath.  Considering so many cars have the protective "cage" removed, and people don't replace it because it is so expensive only makes things worse.

2)  Replace the fuel tank if you find any issues.  Drastic?  Expensive?  You bet.  I fought problems for some time, finally an experienced mechanic took a look see and said it's the tank.  After 40 years, the internal coating is compromised, nearly microscopic rust particles form from the water in the system (ethanol, condensation and old age) and start wreaking havoc throughout your fuel delivery system, clogging screens and filters.  You can try all kinds of stop gap measures but there will be no getting around it if your tank has begun to deteriorate.  The downside is that you will never be able to get in the car and drive with any confidence for any distance unless you find the problems and solve them.

Don't forget the fuel lines and hoses.  A good friend of mine had her late model MB's underbody fuel lines corrode, so if you have original fuel lines, best to replace particularly if you invest in things like a new tank or something.  Cleaning and blowing out the fuel lines was the first solution to my problems but there were no issues there.

Last I checked the fuel pump cages were available (but expensive) and the tanks are available OEM as well as repro for the 280's.

[MBasile]

Thanks for the responses everyone.

ja17 I'll check the filter, seeing as I put a new one in I guess I'll get a pretty clear picture of what is coming out of the tank.

lurtch Mine is definitely in better shape than that one, although the filler neck isn't exactly as pretty as that on my Subaru.

mdsalemi I'll check the wiring to the pump next time I'm down. As for the tank, is it a better value to get a new tank rather than get the current one cleaned out and reconditioned?

Thanks all!

PS: Is there anything I should check around the fuel injection pump?

[mdsalemi]

Because of this contraption inside called the "flower pot", conventional gas tank treatment by coating does not always work.  The people that do it may offer other suggestions, and some have had their tanks redone.  My own opinion is you are just buying some time, and you'll eventually have to replace and by then the tank will cost even more!  Just my opinion though.  I changed the tank and have not looked back.

[MBasile]

Because of this contraption inside called the "flower pot", conventional gas tank treatment by coating does not always work.  The people that do it may offer other suggestions, and some have had their tanks redone.  My own opinion is you are just buying some time, and you'll eventually have to replace and by then the tank will cost even more!  Just my opinion though.  I changed the tank and have not looked back.

That's what I was thinking (not about the flower pot, but as being a temporary fix). I'll investigate the condition of the tank next time I go down to it. I'm still wondering if there's anything I should look into with the injection pump, as I want to rule out as many things as possible in one visit.

[jacovdw]

The injection pump is the absolute last thing to be touched on these cars.

Start off with the basics first:

• correct sparkplugs (heatrange and gap)
• correct valve clearances
• correct dwell angle and ignition timing
• timing chain with no stretch
• correctly set throttle linkages
• clean fuel filters
• good fuel flow to the injection pump

Once all that is done, then you can start thinking about the fuel injection pump.

[MBasile]

Thanks for the help everyone. I opened the fuel filter canister an the filter element looks fine. I was unable to get the fuel tank drain plug out (don't have the right tool) but the filler next looks ok, not too bad. I added more fresh gas (5 gallons) an made sure the linkages we all correct. The car now idles fine (idled for 30 minutes without issue) but it does not like to go into gear (it's an automatic). It'll idle in gear and creep around the driveway, but if I apply too much brake pressure it stalls. I've checked the dashpot and it has now has zero clearance when in neutral and running, but I'm unable to check if it has the correct travel when placed in gear.

Any new tips now that I'm narrowing down the issue?

[Cees Klumper]

here's what I would do given your symptoms:

- Put in a fresh set of spark plugs
- Check the resistance on the sparkplug wires to make sure they're allright
- check the ignition timing - you might even try loosening the distributor a bit so you can turn it by hand as the engine is running, to see if it makes a difference when you try to accelerate (in neutral)
- measure the fuel flow

You should see the constant speed solenoid move the gas linkage when you put the car in gear (friend in the car, foot on the brake) enough to ensure the idle RPM's remain constant. It's possible the thing is worn out (they are not cheap to replace) but, from your description, this may be an issue but it would not be the issue that causes your car to stall when you drive it (beyond idle, the CSS has no impact).

[MBasile]

I know the CSS does move, because it has no contact with the linkage with the engine off, but when the engine is at operating temperature it has contact. Maybe I need to adjust it?

[jeffc280sl]

Cees and others have mentioned measuring fuel flow.  This is accomplished by disconnecting the fuel return line from the damper container to return line.   Hold the hose end into a measuring cup.  Turn on the ignition and measure the time it takes for delivery of one liter of fuel.  Max time is 15 seconds.  Let us know if the fuel injection pump is getting proper fuel volume and we can go from there.

[230slhouston]

Hi,
Here is my experience, I bought a 20 year old barn find 230sl, partially stripped. i assembled the car, replaced all the filters, fluids, put in new plugs, set the timing etc. I had the tank redone using the renew process. Started the car after five minutes of cranking. The car started fine, idled and sounded great for a 20 year old mothballed engine.

It took me a few weeks to finish most of the assembly and was ready for a test drive. In the interim, I would start the engine hear it idle and get excited. At some point, it died and would not start. I tried everything, finally put another new set of plugs and it fired right up. Finally took it for a drive, less then a mile, I started loosing power, idle dropped, came back home and after idling it died again. It would not start. Put in a new set of plugs, it fired up and sounded great. Took it for a drive, after 3 miles, again, started loosing power , low idle, brought it home, it died and would not start. I put in a new set (fourth time) of plugs , it fired right up. After 7000 miles, I have the same plugs and often do an Italian tune up at 90 plus MPH.

I have no explanation except, the experts in this forum often refer to the importance of fresh plugs. I use NGK's. Whatever, it worked for me. Look at my Ellary posts.

Good Luck,

[MBasile]

So here's what I've gathered from the recent responses

•Check/replace spark plugs and wires
•Check the timing
•Measure fuel flow
•Check that the CSS is functioning properly (any movement measurements for that?)
•Check that the fluid coupler is functioning properly (lift rear end, place car in gear. suggested by an outside source)

[ja17]

Hello,

You can spare yourself the expense of replacing your nice original ignition wire set by checking the condition of the insulation then checking the entire wire including the ends with an ohm meter.

The ends of the original wires are re-movable for replacement if needed.  Once the original wires are gone, they are gone forever. I know original wire sets with well over 150,000 miles and still doing fine. On rare occassion a resistor end may fail but it just screws off and can be replaced.  The wires themselves are solid copper and as long as the insulation remains good they will last indefinately and are original.

[Cees Klumper]

So here's what I've gathered from the recent responses

•Check that the CSS is functioning properly (any movement measurements for that?)
•

As for the CSS, it's actually easy to check / adjust it: when put in gear, the idle RPM should not change. If it does, you can adjust it by lengthening or shortening the rod.

I had a similar running problem on my riding lawnmower last spring (Kawasaki four stroke engine, about twenty years old). It would run ok, then start stumbling and dying, then would not start at all. I tried a bunch of things but, in the end, just changing the (single) spark plug would solve the issue each time. I ended up doing this three times and, since the last time, the engine has run perfectly. This mower had also sat unused for two years so could have had contamination in the fuel system that finally worked its way out, but until it did was fouling out the plug. What surprised me was that even a new plug, after fouling out, I was not able to clean in such a way that it would work properly again. Seems like once they 'go bad', they are lost. Fortunately, they are not expensive. I got the parts and manual to do a proper tune-up next spring and that will hopefully prevent the issue from coming back.

[MBasile]

As for the CSS, it's actually easy to check / adjust it: when put in gear, the idle RPM should not change. If it does, you can adjust it by lengthening or shortening the rod.

Should the CSS be making contact with the linkage when the engine is off? There is about 1/4" (about 6mm) of clearance between the CSS rod and the linkage when the engine is off. I couldn't really find much information about the correct measurements for it in the linkage info.

[Cees Klumper]

I'm not positive, but I believe the CSS is supposed to be just clear of the linkage - 'at rest' it should not interfere with the linkage.

[MBasile]

I'm not positive, but I believe the CSS is supposed to be just clear of the linkage - 'at rest' it should not interfere with the linkage.

Ok, thanks. I got my factory service manual cd in the mail today, but even it doesn't have much info on the CSS.