s203 c270cdi(wont start)

[danielsm4a11]

hey guys im searching for help!
Soo my problem started with bad start, rebuild the fuel pump, new orings, new pipes, ( gas tank doesnt have a fuel pump)
the fuel supply now is perfect no bubble!
new glow plugs new glow plug relay, pre heating working, engine rebuilt good compression.
but the problem now is its going good for 4days, the engine starts half egine revelution, the generator charging 14.7v( also new battery Deta senator 100A)
The problem is its showing undervoltage but the battery is 12.8v, the ecu doesnt open the injectors, you can crank the engine for 4h it wont start.
i suspect the ecu doesnt get enough voltage or whats the problem i dont understant, the car is getting on my nervs, then i put aa new negative cable its started then after a week i cant start the piece of **#%, so i really searching for someone who can tell where to look for the problem

 

[ajlsl600]

Suspicious of crank sensor. U can try that or go for diagnostics, if intermittent diagnostics should have a stored fail to start code. So best put on a code reader also check, confirm all such start related harness you may have disturbed something during ur stated overhaul. Be methodical don't flit from one idea to another as u can compound the problem with other unintended issues. Anything desturbed (apart from you) whilst dealing with neg cable? Don't rule out a misbehaving and even new batt modern benz hate any sign of batt prob. Try jump starting from another Good source. But Follow ur hand book exactly on that process

 

[M80]

You sound sure you have primed the fuel system, as said no lift pump, these can be a bitch to pull the fuel through.
But if I read correctly you've had it running for 4 days.

I would be looking at the fuel rail pressure to eliminate the ECU inhibiting the start till that's reach threshold. An air lock could cause that (unlikely if it's been running for 4 days), as could excessive leak off.

Where are you?
Is the no start issue after on over night stand? more in cold climates these are known to pull air in through the fuel line 'o' ring/s.

You can go through the basics but likely w/o a good diagnostic to point you you might be trying different stuff for a while.

 

[danielsm4a11]

You sound sure you have primed the fuel system, as said no lift pump, these can be a bitch to pull the fuel through.
But if I read correctly you've had it running for 4 days.

I would be looking at the fuel rail pressure to eliminate the ECU inhibiting the start till that's reach threshold. An air lock could cause that (unlikely if it's been running for 4 days), as could excessive leak off.

Where are you?
Is the no start issue after on over night stand? more in cold climates these are known to pull air in through the fuel line 'o' ring/s.

You can go through the basics but likely w/o a good diagnostic to point you you might be trying different stuff for a while.

Hey, there are new orings, fuel pressure regulator, also pipes fuel filter, i can say the fuel isnt the problem, 140bar pressure when cranking, and holding pressure just fine, the non atart acures when the display shows undervoltage, but if it runs it runs amazing

 

[M80]

Is this an under voltage prior to cranking, or during?

Maybe check the voltage at the fuse enclosure bus and compare.

 

[supernoodle]

140 bar isn't enough. During a crank rail pressure would normally be 250-300 bar. Injection won't be released until >150bar.