OM603: Cranking Time Post-Fuel Filter Change
 

Hello,

I'm a new owner of a 1987 300D, and am quickly growing to love this car, though right now it won't start.

I changed my fuel filter today, and as instructed in the Bentley "Owner's Bible", poured the fuel from the old filter into the new (I've since learned this is a bad practice) which filled it approximately 60% full. The engine started right up after this, ran for about 20 seconds, and died. I have been unable to start it since then.

I read that a couple thirty-second bursts with the starter, with my foot on the pedal all the way down should do it. Problem is, I've done about six 30-second bursts, and the battery is starting to run low (it's currently charging).

Should I start to worry, or is this reasonable behavior when a new fuel filter is not 100% topped off? What's the longest you've heard an OM603 needs to crank before starting?

Thanks very much,

Matt

normal, just charge up the battery and try again. Also bleed the system from at least one injector line by loosening the collar nut, this will help.

They usually start immediately and might stumble or stall once or twice.

But, that's with a full fuel filter.

With a 60% full filter, all bets are off. All that air must be forced through the IP.

If it were me, I'd go and get some fresh fuel and fill the secondary filter and try to start it again.

We did recently have a fellow who never got it started. Turns out the fuel pump went bad. How, or why, the pump failed at the precise moment of the fuel filter change remains a mystery.

What I did was fill the filter right up with a diesel additive, forget the old stuff, and then turn the ignition key as far as it will go before the engine turns over, You should hear a clicking sound which is the fuel pump. Once it stops, crank the engine. MB can be run dry and still started in contrast to my VW TDI's which if run dry, you need to crack open the feed lines on every cylinder to let the air out. MB are self priming or whatever you want to call it.

The OM603 has a mechanical fuel pump.........there is no "clicking sound" that eminates from the fuel pump. The pump doesn't turn unless the engine turns.

Sometimes the engine will start without cracking the lines to the injectors..........sometimes it won't. Depends on the condition of the injection pump, apparently.

Sorry....

Can you help me by telling me exactly how and where I am to loosen the injector line in order to allow the air out, as suggested?

Thanks very much,

Matt

There are six nuts, one at the end of each injector hard line, that connects the hard line to the injector. If you crack the nut, the line will bleed off an air that's trapped in the line. Once you've cranked it once or twice, you'll see fuel coming out of the lines. Then you tighten them back up and start the engine.

So, I went ahead and cracked all six lines. We're still not getting fuel out of any of them, and have now cranked for a total of about 80 seconds.

This is after about 240 seconds total cranking earlier today before cracking the injector lines.

It looks like fuel is going through the prefilter, so I'm a little confused as to what is going on. Any thoughts or potential ways ahead?

Also, thanks to all for the informative and quick responses. This forum is great!

--Matt

Do you think there could be any connection between the two events? I'm beginning to suspect something similar with my car.

-Matt

I certainly do.

Disconnect the line from the pump to the secondary filter and crank the engine. See if the pump is providing any output to the filter.

Alternately, drop the secondary filter and see if it's full. With all that cranking, the pump should have filled the filter by now.

Keep cranking it will start. Let this be a lesson, don't run a 603 out of fuel!:eek:

.......not if the fuel pump is toast.........:eek:

I don't think the fuel pump would go bad all of a sudden? Well if he thinks thats it buy one and stick it on. Can't hurt to replace it, in my book if its 20 years old its due!:D

Why not drop the spin on down and see if its full of fuel? If it still has the amount that you put in it, then a bad fuel pump is probably a safe bet.

There you go, looks like they went up a bit recently:
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1UO15Z3SZ1VT1AQ0DC&year=1987&make=MB&model=300-SDL-001&category=All&part=Primer+Pump+Assembly

The last time this happened...........a couple of weeks ago.........the member did exactly the same thing and got only a couple of drops out of two injection lines.

http://www.peachparts.com/shopforum/diesel-discussion/161211-cant-pull-fuel-bottle-am-i-doing-right-thing-replacing-fuel-pump.html?highlight=fuel+pump

The pump failed during the attempted restart.

There might be something related to the pump attempting to force fuel into a space filled with air.............