2005 Freightliner with a mercedes engine wont start

Are the batteries fully charged? All of them? Even one weak/dead battery is enough to make the truck next to impossible to start.

If the batteries have recently been messed with, there is a small wire in the battery box that needs to be connected....goes to the ECM or something like that....it's easy to miss, but if you DO miss it, that truck won't fire up.

I'd start there.

 

You say it starts with start up fluid.
Does it then run or does it die once you stop injecting the start up fluid?

It could be an ignition problem.
Power cut to the shut off valve when key is in start position , once truck key is in the on position power is restored.
Because truck starts on starter fluid you return key to the on position while engine is still turning and the shut off valve is powered.
Diesel flow is restored and truck runs.

 

When I was a company driver, I had an '05 Freightshaker with a Mercedes engine. 1 dead battery w/ 2 good batteries and the truck would turn over, but not start. Took 3 large commercial batteries, 1 deep cycle 1100cca marine battery, and my pickup all hooked up to the truck w. jumper cables before there was enough juice to overcome that 1 dead battery. Drove it to a company shop, where they replaced the 1 battery that tested bad. They refused to replace the other 2.

The next night, I was at a motel...not at the house. So when the truck didn't start, I had to call them to have a road service truck sent out to me. Guy shows up, decides to test each battery before attempting to jump start the truck...in the process, he missed that thin little wire and spent the next 5 hours trying to jump start, pull start, and every other thing he could think of to get the truck fired up. FINALLY, I was on the phone with the company shop and they head guy asked about that thin little wire. Sure enough, it wasn't connected. Hooked it up and the truck fired right up.

When troubleshooting, start with the simple things and work your way up to the more difficult stuff. Never assume anything...check it out for yourself.

 

If it is a manual transmission.
Park it on a bit of a down hill with the air tanks full.
Put it in 3rd gear and shut it off.
Turn the key to on and let it roll with the clutch depressed.
Release the clutch gently while applying a bit of pressure to the diesel pedal.
If the truck starts then the shut off valve is probably not getting power from the ignition when in the start position.

 

How long are you cranking it before you give up? If the truck is losing it's prime to the injectors then you will have to crank it for a few minutes to get it going (hold pedal down to operate the electronic throttle valve) and it still may not start. It sounds like that is your issue. My FLD used to do this if i drained the fuel filter. It would crank and crank but not fire, but with a shot of starting fluid it would fire up and regain it's prime.... I think that is your issue here.

If the ECM wire was not connected, it would not run at all. So my 1st issue would be to find out why your losing your fuel prime. Most likely a faulty check-valve going back into the tank on either your return line or your primary line.