My 280 has recently started to stall randomly and completely. Most of the time it will restart right away, other times, it requires a few minutes and/or an underhood visit without really doing anything but touching wires, etc. My guess is that this extra activity provides nothing more than more time for the car to sit.

On the last fill up I added two bottles of HEAT-type fuel system dryer and a 1/4 bottle of Castrol gas treatment/octane boost. Prior to that the only thing remotely close to this cutting out was some very brief cuts when cold, but nothing substantial enough to cause worry of a stall.

I've approached this from the aspect of a fuel probem so far, thinking that the additives have dislodged something that is plugging the fuel system momentarily.

After last night's ride home on a AAA flat bed, I layed in the driveway in the snow and removed the fuel pump. I removed the top and cleaned the screen and the reinstalled it. I removed the fuel feed to the carb and cleaned that screen.

I see no other fuel filter besides these two screens. I looked up the fuel filter on the Mann website and one is listed. Is that just missing from my car or was it not commonly installed or have I just failed to find it? There is nothing out back by the tank.

On the Mann website I found a reference to a part which looks like it is in the tank, a pickup with a screen, so I'll check that next.

I was also going to buy some sort of inline filter to add right before the fuel pump.

When the car stalls it is complete and sudden usually with no sputtering, save for a catch or two then total death.

I've noticed that the car seems to have some sort of electronic ignition module. This was not present on my parents' depated 1973 280 that I was familiar with in the past. Is this electronic ignition something that someone added along the way or was it an update for 1974?

Thanks in advance
Ed
Colorado Springs

ekellock-

to me, it doesn't really sound like a fuel problem. If something were restricting the fuel it would sputter a little before stalling. I think it could be electrical. With the car being that old, you just never know. I'd check the coil, plug wires, plugs, distributor, rotor, things like that. Good luck....

-Biggs

All M110 engines had electronic ignition. Up to 1976 they were point triggered (mechanical breaker points that open and closed to inform the module).

These points were easily fouled as they had very little current flowing. I would suggest pulling a clean piece of paper through the closed points. You will probably get a blue smudge. This can be all you need. I doubt seriously that a carburated car would stop abruptly due to fuel and recover on its own. Much more likely an ignition problem.

As to filters there are none. There is probably a screen inside the tank where the fuel outlets and there is a screen in the inlet to the carb.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

I recall setting the dwell on the breaker points in the distributor on my parents' 1973 280. Are these the points that you refer to; are these the points that trigger the electronic ignition?

Yes, those are the points. In 1977 they were replaced by an inductive trigger.

In standard ignition the points carried the current to power the coil. In these, point triggered transistor ignitions, the points only act as a signal to the control box that handles the coil load. Among the advantages to this was that the coils could be run with much higher current flow than the points could handle. Point ignition burns out above 3-4 amps while transistor ignitions regularly handle 10 amps.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Excellent. Thank You! I had not even checked inside the distributor, linking this behavior with the recent fuel-up. I'll be under the hood again this evening after work and I'll follow up here afterwards.

Ed
Colorado Springs

As it turns out, my car does not have breaker points in the distributor. It has some sort of wheel with six "petals" and an electronic eye which seem to satisfy the function that mechanical breaker points normally would.

I did find that a jumper wire inside the distributor, a ground wire I believe, was quite frayed, so I removed the distibutor and resoldered it.

Also, the vacuum advance hose is not used, a detail which I had forgotten about in my earlier mail. I attempted to reconnect this some time ago and found that the engine would not run properly.

On the driver's side inner fender wall are mounted two finned alloy boxes. One is a Bosch item (p/n 0227 051 014 I believe), the other is smaller with the name Lumenition embossed on it. The wires from this box connect to the distributor. Anyone have any info on this piece?

After the distributor r&r, I started the engine and let it idle for a while. After it had warmed partially, having idled smoothly and steadily the whole while, it again stalled suddenly as before. I was able to restart it and the cycle was repeated several times. It occurred to me then that the stalling seems to only occur when the engine is partially warmed. If I am persistent and keep restarting it and it gets fully warmed up, it no longer exhibits the stalling behavior. I have in fact driven it all over town on warm day without incident.

So, I am now wondering about anything that might be active during the warmup cycle. What are the functions of all the sensors on the passenger side of the head? Are there any other sensors or warm-up cycle functions that might fail in some way that might cause sudden stalling?

Thanks in advance once again.

Ed
Colorado Springs

Still troubleshooting this. Condition has worsened. Car died in drive-thru line and wouldn't restart for a long time. Then when it would, it would not stay running for long. No sputter, just complete shutdown as if key was turned off. Car returned home on flatbed.

Have verified no spark at coil UNTIL letting off key from start position (back to run position). This is consistent with lurching of engine (as if it wanted to start) just when key is released. No firing at all while cranking.

Checked ballast resistors. The .4 ohm resistor read .6 and the .6 ohm resistor read .8.

Decided to check voltage at input on .6 since the other end goes directly to coil. Battery voltage is 12.2, voltage at input to resistor is 8.2, voltage at coil + terminal 4.5.

Should I see battery voltage at resistor input terminal? Can I run a jumper from the battery to the resistor input terminal as a test?

Have been reading the archives. Found references to similar behavior and mention of OVP, over voltage protection relay. Does the 1974 280 have one of these?

Thanks in advance for any and all input.

Ed Kellock
Colorado Springs

Any update to thread? Just wondering what was found wrong to cause the problem.

Gympie

The problem is as yet unresolved.

Here is the latest info in regard to my troubleshooting efforts...

I finally ordered a CD to get the wiring diagram.
I jumpered the plug on the ignition switch and still no start.
There are 2 30's and 2 15's and one 50. I jumpered one 30 and one 15 and the 50 together. The starter cranked, but still no start. Do you think I'd have to jumper all five together?

Things I've verified:
No spark on coil wire.
Have tried two other different coils.
4.5 volts on coil + terminal with an increase in voltage while cranking only once in a while (the only time it will start).
I've jumpered the neutral safety switch.
all the wires at the ballast resistors seem to have the appropriate voltages, except for the spike from the starter when starting. I do get 8 or so volts on that wire, both ends... the end at the ballast resistor and the end at the connector block on the passenger side inner fender well.

Is the starter solenoid responsible for the power spike during starting?
If so, could then all other starting functions work correctly except for this one?
Bad starter solenoid?
If it's just this slight increase in power that gets it to start, then wouldn't feeding 12 volts directly to the + terminal of the coil make it start? (because that doesn't help.)

Ed
Colorado Springs
4-wheeled, star-emblemed, maple yellow lawn ornament.

Ed,

What have you done since to troubleshoot the problem? I own a '76 280S and have had similiar problems. Do you have fuel injection or a carb? Also, you mentioned that there is no points, is this correct?

Gympie

The car has the standard carb. It has a Lumention ignition add-on which replaces the points.

What have I done to troubleshoot...
Ohmed out the ballast resistors.
Checked voltage at each wire according to the wiring diagram in the MBZ M110 engine book.
Renewed ground connections at battery, under coil mounting clamp, and engine ground straps.
Removed and reconnected all connections at alternator and sprayed with De-Oxit.
Tried two other coils.
Renewed the connections at the test block right by the coil.
Ohmed out the wire from the starter to the ballast resistor.
Jumpered the wires to the neutral safety switch together.
Pulled the plug on the back of the ingition switch and hot-wired it.
Have connected a timing light to the coil wire. No flash = no spark, right?

On the rare occasion when it will start, it seems to run perfectly, smooth idle, smooth rpm ramp up when gassed. When it dies, no sputter, it just quits, as if I turned the key off.

Neither the engine manual nor the CD have anything about the starter, solenoid, and the wiring related to either which I'm curious about because of the voltage spike that I've read about that should be present while cranking. The only time I've seen more than 4.5 volts at the coil + terminal is when the car starts. I've seen anywhere from 6.5 to 11-12 volts very briefly there, again only when the car starts. The last time for this was a month ago.

Not to familiar with the Lumention ignition add on. Do you still have the connection to the switch gear, or ignition contol box, or is it bypassed? Does the Lumention ignitor have its own control box?

Have you ruled out any fuel problems? What carb does it have?

Gympie

Hey, im a complete newbie to this, but with my 73' 280s on the passenger side behind the light there is a resister with a white box thing over it and it has 2 tweminals on it, it think it is part of my imobiliser system, but i had similar problems and i tracked it down to these terminals.... all they needed was a clean and i havent had this problem since! hope it helps!

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73' 280s