paalw

My car (W211 E220 CDI, 150000 miles) suddenly won't start, just cranks but no start. No errors in displays or anything. Started fine 2 hours before.

Ran a STAR test and these errors came up. Are there some good STAR interpreters here?

Attached star errors:

cmriv

FUEL PUMP....

Plutoe

Clear all the faults---start the car and do another quick test---which faults return!!

paalw

The same ones returns. They are current.

Also did another test with the diesel pump disconnected, I then got the exact same errors + a couple of new errorsregarding the tank level sensors(which I guess are the 3 thin wires on the connector).

I then put a multimeter on the two thick wires to the pump, and measured while turning ignition. No voltage.

Then checked fuel pump relay in trunk for click, yes it clicks when turning key both ways.

20A Fuel pump fuse is ok, but when measuring voltage there while turning ignition there is nothing happening there either. So. Thats where I'm at now.

Is there a main fuse another place, or something else that could cause this no voltage situation? Doe this make sense at all? Wouldn't a bad wire somewhere just blow the fuse? *conFUSEd* :p

Plutoe

Have you double clicked on the fault to determine the prescribed test for the issues before you start purchasing parts.

The first three fuel related faults seem very odd--fuel pump--rail pump-rail pressure control the only component that was not producing a fault was the injector!!! With all short to ground!!(the harness is in good shape)

paalw

Hi and thanks for your contribution. No I haven't double clicked. Didn't know that was possible actually.

I'm not sure i get your point from the last sentence. Maybe because my mother language is not english, or maybe I am just dumb Can you elaborate? For sure these errors must all be connected in some way? The harness is in good shape, how do you conclude?

mersum1es

I think meaning is that if ALL those components go short to ground at same time, it is very odd, and points somewhere else than those individual components... Have you checked your front/rear SAM and aux battery area that there is no signs of water flood?

By clicking fault you'll get sometimes (depending on fault) condition data when fault has occurred. And proposed test procedure may give you more places to measure voltage loss.

paalw

Yes I agree, very unlikely those would all fail. What I thought was that maybe one of them fails, and the other errors are consequense of the first fail?

I have checked rear mail battery and aux battery, both fine and fully charged.

What I find strange is that there is no 12V to the diesel pump or by the pump fuse when turning ignition on. It's supposed to prime then isn't it?

Plutoe

Yes, poster 7 and 8 have the correct interpretation of the word "odd" = unusual or weird or irregular or random or varied-----------there is something else going on in the fuel delivery system.

In any event I would follow the test procedures in DAS Xentry---now the fun part begins--test test test for a solution------

paalw

Correction: When I measured V on the fuse inlet i did it wrong way. I put + and - in each of the fuse holes. Obviously thats not gonna give any answer. So please discard information regarding 0 V at fuse. I will measure again tonight. Though the measurement of 0 V at the pump should still be valid.

Will also do another diag run and see if I can get into the specified tests.

Thanks.

paalw

Ok, so I measured V at the pump fuse again. Confirmed constant 12V. So that is good I guess.

Then swapped starter relay with pump relay and tried to fire. Same thing. Cranks but no start. So relay is (probably?) good.

I then disconnected pump cable and tested direct 12V to pump. Pump is running.

Is the pump supposed to prime when ignition is turned on? Because it does not. If it is supposed to, i guess I have to measure resistance from relay to pump connector cable(?), or any better ideas?

I have not yet figured if the pump is running while it cranks. Cant hear because of noise, and havent had access to help for that.

(Also ran diag and tried to doubleclick error, it told me to check relay, measure ohms etc)

cmriv

yes pump is suppose to prime-it is not suppose to be a constant 12v. Just a surge.

paalw

Todays testing:

Bypassed pump relay and pump is running.
Tried starting while bypassing relay and pump running. Still no start.

So, I haven't actually confirmed that the pump delivers fuel - but it looks and sounds like it when it's running. I think I have to move to the engine bay for further testing.

Are there any nice tricks for measuring fuel pressure? Does it show in DAS btw? Never done this before so I have no Idea. Will try to read up on pressure pump, pressure valve and quantity valve.

mersum1es

There is no gauge for primer pressure, but rail pressure you can see. Should rise rapidly over 200-250bar when cranking.

paalw

Summary of my testings so far:

Fuel pump does not prime, or run at all when cranking. Pump fuse and relay is ok(tested 3 relays). Bypassing the relay makes the pump run, and deliver. But when trying to start with pump relay bypassed and pump running, no start then either.

So, this tells me therelay control for the pump is not acting as it should(maybe bacause of another fault, this is set to not engage in this situation? who knows). There must be more too, if it had only been the pump relay control, the car should have started when bypassing relay.

Beginning to think I have to bite the sour apple, resign, take it to an MB workshop...running out of ideas.