124 87 260E possible fuel issue

[dlssmith]

I've searched quite a bit about this particular issue, but am looking for a way to narrow my problem.

My 260 with 135k miles, has new dist, plugs, wires and she starts quite well when warm, barely turns over before firing up.

However when cold it sputters and spurts for about 30-45 seconds before evening out. Once even, she runs good.

There is also an intermittent lack of power on acceleration sometimes. Often she is quite speedy other times she doesn't seem to be getting the fuel needed to climb an on ramp or whatever.

Cold start valve, fuel accumulator and some of the other stuff are fairly expensive parts. I can take it to my indy but sometimes he gets to the issue, sometimes not.

Thanks in advance.

[Golden80s]

How cold does it have to be to start poorly?

The reason I ask is that I had a similar problem with my 560SEL and like you worried that it was the fuel distributor etc but in the end it turned out to be bad injectors causing fuel dribbling and bad spray patterns. My symptoms were when hot or fully cold (overnight) good/fair starts respectively but when 1-2 hours cold very poor starting combined with a loss of power.

135K is about time for new injectors anyway if they haven't been changed already.

Hope this helps!

[dlssmith]

It's been exhibiting the symptoms when cold almost no matter what the ambient temp is. 30 f or 70 f. Same behavior.

Does one buy new injectors or is it better to have them cleaned professionally or is there a rebuild for them?

[Golden80s]

No rebuilding is possible at all - or really effective cleaning for that matter.

They are basically a wear item like plugs are.


Bosch (which is what is in the MB box anyway) injectors run about $40 each so you'd be looking at c. $240. In my experience, they last about 100 to 125 thousand miles. In fact, I am getting ready to replace them on my 560SEL for the second time at 190,000 miles on general principle


The reason I asked about how cold is that when injectors “dribble” out you tend to notice it most when the car has been sitting less than a few hours but more than a few minutes. A few minutes, and not much fuel has had a chance to leak out and what has cooks off. Overnight, what ever fuel that was going to leak leaked and has gassed off or gone into your oil


Bad fuel distributor symptoms tend to be more severe in my experience and pretty independent of operating temperature. How is the mileage? How does she idle?

[dlssmith]

She idles well, not perfectly smoothly, but never hesitates and doesn't die - except during the first 30 seconds post cold start.

Mileage is ok, about 22 mpg on the highway, 15-16 commuting and around town.

I was wondering about the fuel accumulator - not sure if that can be tested; but it is supposed to maintain the fuel pressure/volume when the engine isn't running.

[Frank Reiner]

Look to the electric heating of the O2 sensor. A usable signal from the sensor depends on it reaching ~600deg.F. The electric heating reduces the time to reach temp. A poor running time of 30-35 seconds post start corresponds with a weak or failed heater. The occasional poor acceleration also suggests an intermittent loss of O2 signal.