E280 starting probs

[flagstaff]

... wonder if anyone can help me with this one: just swapped the cylinder head gasket on my '93 e280 for one that wasn't leaking. everything put back together correctly, timing etc ok. but it won't start. it fires, but then dies. there's also a squealing sound coming from the rear somewhere, which i assume is the fuel pump. i'm guessing that it's unlikely that the fuel pump will lhave chosen this exact moment to stop working ... although you never know.

the only thing i think i may not have put back together right is possibly the fuel feed and return pipes, which are similar and very close together on the fuel rail. when i have them in one configuration, the engine turns but never fires. in the other, the engine fires as i said above, but then dies almost immediately.

this one's really puzzling me. before the cyl head came off, the car was starting and running sweetly.

cheers for any pointers guys

 

[paulcallender]

The thing that makes my ears prick up is that it fires up briefly. So, its not the ignition or valve timing out, which is a distincy possibility with removing a cylinder head.

I would suspect the main fuel delivery, whats probably happening is that the cold start injector is delivering some fuel but the others aren't, therefore it fires for a little while. You could try 'feeding' the engine with fuel by taking off the air cleaner, then squirting petrol at the throttle valve whilst it starts/runs. Or a good squirt of cold start spray.

 

[flagstaff]

hm. what you say sounds right. i'm not actually sure where the cold start injector is on this model; there just seem to be six injectors, and that's it.

actually, thinking about it: you're saying there is no separate injector for cold start, but a separate electronic circuit.

it's an avenue to investigate, that's fo sure. maybe there's something i just haven't plugged in, somewhere. when it's light i'll have a look.

thanks for the reply, paul.

 

[kth286]

flagstaff

Unfortunately paulcallender does not realise your model is all electronic where the ECU controls both fuelling and ignition.

I would suspect because of the engine wiring harness problem on this engine that whilst doing the head work, as the coil feeds are brittle, you have moved them and caused the insulation to fall off inside the thin outer covering, therefore the wires are now shorting out the coils.

Be careful, if that is the case, you can also short out the ECU at a cost of some £1,000 plus labour (but very easy to fit - do not ask me how I know)
A new engine wiring harness is some £550 plus fitting (again you can do it yourself in one or two days and save some £600 labour.

Having said all this - do not panic - but you do need to get your diagnostic codes read as a first step.
You will need to get a Merc specialist to visit you - no one else.

Trust it all goes well.

Regards

 

[paulcallender]

You're right - I made the error of thinking it did! But, I had the right idea. The problem relates to taking apart and then putting back together, a lot of components. I was looking for the 'thing' not put back in the right place, not the thing inadvertently broken in the process. If you've really damaged your loom, I feel sorry for you - those things are well costly!

 

[flagstaff]

flagstaff

Unfortunately paulcallender does not realise your model is all electronic where the ECU controls both fuelling and ignition.

I would suspect because of the engine wiring harness problem on this engine that whilst doing the head work, as the coil feeds are brittle, you have moved them and caused the insulation to fall off inside the thin outer covering, therefore the wires are now shorting out the coils.

Be careful, if that is the case, you can also short out the ECU at a cost of some £1,000 plus labour (but very easy to fit - do not ask me how I know)
A new engine wiring harness is some £550 plus fitting (again you can do it yourself in one or two days and save some £600 labour.

Having said all this - do not panic - but you do need to get your diagnostic codes read as a first step.
You will need to get a Merc specialist to visit you - no one else.

Trust it all goes well.

Regards

eek. is it worth stripping back the loom to find a break? i think i know the answer to that one already ...

 

[flagstaff]

actually, on reflection: the £700 or so i saved doing the job myself could be put towards a new loom. just looking on the bright side, here

 

[tom7035]

That's always the best way to look at things!

 

[Mid_lfe_Crisis]

Isnt the fule pump realy a 2 stage realy ie 1 stage main running and the second stage for cranking could it not be this as it fires when cranking then dies off the key ????

 

[Richard Moakes]

On most fuel injected cars the fuel pump is two stage.

When cranking, the pump is always energised, however when you release the key back to the normal run position, a signal is required from either the air flow meter in older LE-Jetronic type cars, or from a crank rotation sensor in later cars fitted with MAF's, actually I think a crank sensor is also used in KE Jetronic as well.

If it fires when cranking but then dies, have a good luck at your crank sensor and fuel pump relay.

Good Luck,

Richard

 

[flagstaff]

Thanks. this gives me something to look at before biting the extremely expensive bullet of a new loom.