3406e 5ek no start

Hey all, we've got a 94 freightliner with a 3406e in our fleet towed into the shop with a no start.

Story goes, driver was just chuggin along when the truck started to run like a sack of #### before stalling out and not being able to start again. It does crank over.

We weren't able to connect our scanner tool. I checked for reference voltage at a few sensors and only had >1v reference.

Found the oem plug on the ecm barely Held in and the hold down bolt snapped in half. While one guy held the plug into the ecm socket (40 pin) another cranked her over to no avail. I checked the switched and unswitched powers and ground (load tested), and they all passed.

We replaced the ecm with one from a reputable shop who flashed it up to our required parameters.

Still no start but now i do have reference voltage.
I was able to connect to the ecm with cat et but unfortunately wasnt picking up any codes. After running a few tests i noticed we had no speed on the tach nor was cat et picking up engine speed. I replaced the cam pos sensor and the crank pos sensor to no avail. Circuits test fine. No power to injectors while cranking.

I know that when you replace an ecm or cam pos sensor you are supposed to calibrate it, but the engine needs to run to do so.

Any ideas would be much appreciated. This truck need to get back to work as soon as possible

 

Clogged fuel filters would shut down engine, and it would crank and not start.

 

Agreed, id start at the fuel system unless something is pointing to electrical

 

Absolutely everything is pointed to electrical. My biggest concern is im not picking up engine speed-no power to injectors. Fuel primer is hard

 

I'm curious as to how the ECM plug bolt was snapped in half before you touched it. Call me paranoid but this makes me think someone was tampering with your equipment.

 

This is a water truck that takes quite the beating, and remember its a nearly 30 year old truck thats spent plenty time fighting fires in rough terrain.

I highly doubt anyone wouldve tampered with it. When its not working its sitting in our locked yard

 

On my 3406e I dont get rpms to read till its going.

hard primer is good

I know many beleive ether is the devil, but give it a few small squirts and see what happens? Rpm may raise enough to get it some actual fuel/a reading.

A weak fuel pump should have showed slow deterioration.

A possibility, it can happen, not common but not unheard of, pop primer off and check that the checkvalve isnt backwards, it can happen.


Granted all this is fuel related. You say hand pump is hard, is that the only reason youre leaning to electrical? I had a hard primer but it was sucking air in the fuel vacuum gauge hose, primer is between 2 check valves after that hose... a thought

 

This truck is no stranger to either. Especially in the -40c winters we have here. My thoughts are that if the ecm isnt picking up engine speed it wont tell the injectors to fire. From what i understand even if the dash gauge isnt picking up engine speed while cranking the ecm should and i should see tgat in cat et. Ill probably crack a line off the pump to see if im getting fuel but im sure i am

 

I dont actually think rpm is useful here, if im not mistaken (and i could be) crank position and rpm are completely differemt sensors, but as ypu saythe cps cant calibrate till engine is running, this is because its (cam) just not rotating fast enough to send a signal. But the same for rpm...

If im right, ether will give yoy a small blip of rpm both on dash and cat et

 

Well im out off ideas so ill give her a
Try