Hey gang,

We started noticing slightly longer starts recently. When cold it used to start after about 4 revolutions, now it's 5 or 6. Hot it's even worse.

This weekend we drove it to a gas station, filled it with diesel, drove across town, shut it off and 5 minutes later it wouldn't start. It timed out 3 times.

Our friend gave us a jump and it started again, so we drove it home and parked it.

I have been reading up on this for the past few days and have found a few possibilities:

Low battery - the battery is only a year old, but I am going to put it on a charger to top it up.

Weak starter. It sounds fine, but I saw someone else say they replaced the starter and solved this issue.

Porous fuel lines. I replaced the fuel filter 30k miles ago, so I just ordered a new one and a hose kit. The hose attached to the driver side of the filter is looking a little rough. I always like to start with the simple stuff.

Leaking injectors - no signs of a leaky injector at the moment. I did have a bad o-ring 5 years ago which I replaced and it hasn't leaked since.

I scanned it yesterday and got error code 118100 - "Relay F58kD Engine circuit 87 relay switches off too late." I swapped it for now and ordered a replacement with the fuel filter.

Low pressure fuel pump?

High pressure pump? It runs fine once running, so I'm guessing it's not that.

I do have a scanner and can watch the fuel pressure and crank speed. I'm seeing crank speed under 150 RPM (I need to download the data, so don't quote me on that) which would point to a starter.

Any tips on tests to run?

Other things I might have missed?

I do have a copy of the Mercedes EWA workshop manual, but find it incredibly difficult to navigate.

I'm hoping to get at least 200k miles out of this thing, thanks for your help!

 

That really points to the battery...

I had a no-start in the winter a few years back. Everything seemed good, but, when jumped it fired off immediately. I replaced the battery and it's been fine for about 3 years.

 

The battery is only a year old, and just to be sure I tested it, charged it on a trickle charger, and tested it again. It tests right at spec.

 

A week ago I bought a new fuel filter and fuel lines from FCP Euro and replaced then all. It still started slowly, but started. I didn't notice any real change. Unfortunately my scanner only measure once per second so it's not collecting very good data. I'm working on getting software for my new Foxwell NT530 scanner.

Yesterday I replaced the starter, took about 2.5 hours. And today I got a chance to drive it around, get it hot, then try a hot start.

It definitely spins faster both cold and hot, and so far no issues with hot starts. I will keep testing it and report back.

 

So the ML has been starting just fine recently. I feel like it still takes an extra beat to start, but it has started every time since I put in a new starter, hot or cold.

But yesterday it just died on my wife while she was sitting at a stop light.

My next guess is to check the leakdown on the injectors and see if one or more are leaking down and dropping the fuel pressure. I have been looking at videos and it doesn't seem that hard, but if anybody has any tips I'm all ears.

 

There was a known issue with crankshaft position sensors in early OM642 engines that could cause something like this. Just an idea and not sure if a 2010 would be affected.

 

Camshaft and crankshaft sensors are both on my possible lists. But symptoms are still pointing to low fuel pressure in my mind.