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Matt
Matt, Engineer
Category: Mercedes
Satisfied Customers: 20592
Experience:  Mechanical Engineer with 23 years experience in the auto industry, 8 yrs in formula 1 engine testing
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I have a 2009 Mercedes sprinter It was running fine when I

Customer Question

I have a 2009 Mercedes sprinter It was running fine when I finished travelling yesterday when to start today motor turns over as per normal but no sign off firing. WDF9066332EE002899
Submitted: 1 year ago.
Category: Mercedes
Customer: replied 1 year ago.
My apologies after further investigation regarding the year of manufacture it is 09/08
Customer: replied 1 year ago.
I havve also found the engine number which may be of help. 64698551594698
Expert:  Matt replied 1 year ago.

Hello

I'd check that you're getting full power to the glow-plugs, they pull a lot ofcurrent so take care when checking but see if the relay is clicking when the ignition is turned on first and also check the fuse if this is OK check to see if the engine earth strap is also OK.

If the plugs haven't been changed in the last 20K then they may have to be replaced.

You can test the glow-plugs with a multimeter by measuring the resistance across the plug (between the power connection and the body) it should be around 4-8ohms if itstending to infinity / open circuit the plug is faulty or by using a clip on current clamp, either on the supply wire to glow plugs or onto engine earth, with glow plug light on you should see 15-20amps for each glow plug fitted, 4 cylinders would be approximately 60-80amps.

Also if its not injecting at all then check the connections to the crankshaft sensor, unplug itand check for corroded contacts and broken wiring, and consider fitting a newsensor - do the same for the cam position sensor

If the EGR valve is stuck open then this too can effect starting so try disconnecting it to see if this helps or changes anything

Could also be an injector leaking fuel back through the overspill pipe, so not getting enough fuel pressure to tell ECU to fire the injectors, this is trickier to find andyou’ll need the garage to do a ‘run back’ test to identify which one is theissue

Lastly it’s also worth considering fitting a new fuel filter as if only slightly blocked this can lower fuel supply pressure and choke the main pump, the pump will be more sensitive to this when its cold as diesel thickens considerably with low temperatures.

It may have developed an air leak on the fuel supply pipe from the tank to the engine. The engine hasno separate lift pump and relies on the built in one in the injection pump. Ifa leak has developed on the fuel suction pipe then air entering the system willair lock the pump.
Try pumping up the fuel using the hand pump in the engine bay on the filterhousing, then crack off / loosen each injector pipe in turn while cranking theengine and getting an assistant to operate the primer. This will expel air fromthe injection side and the engine should fire up. The problem will be cured bychecking the supply pipe along its length for signs of leakage and repairingany you find.

If you daub eachpipe joint with heavy grease and theissue goes away then wipe the grease away one at a time to highlight theproblem joint

Expert:  Matt replied 1 year ago.

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