Fuel delivery problem? - PeachParts Mercedes-Benz Forum

winmutt · #1 01-22-2007, 10:16 AM

This new benz I have (85) runs like crap when you first start it. It turns over and starts easily enough but has no power and just wants to die. So far I have replaced the fuel filters, swapped the return and supply fuel lines, and replaced the supply line. The bubble in the fuel filter still seems pretty big. Once the car is warm everything is ok. Suggestions?

barry123400 · #2 01-22-2007, 10:24 AM

I would check the valve clearances mainly because it is a good thing in itself. Mainly though I would pay some attention to the injection pump timing. My thought is it might be retarded and the engine wants to die out until some heat is really available. The glow plugs might be covering this up in your initial start. Just some thoughts. Others will have better suggestions perhaps.

winmutt · #3 01-22-2007, 10:30 AM

Quote:

Originally Posted by barry123400

I would check the valve clearances mainly because it is a good thing in itself. Mainly though I would pay some attention to the injection pump timing. My thought is it might be retarded and the engine wants to die out until some heat is really available. The glow plugs might be covering this up in your initial start. Just some thoughts. Others will have better suggestions perhaps.

Did valve adjustment this weekend. starts better but still low power on start. Also there is a ton of smoke during this time. Mostly oil looking.

Stevo · #4 01-22-2007, 11:54 AM

Sounds like one or two bad GPs. I would pull and bench test them to be SURE they are up to snuff.

kerry · #5 01-22-2007, 11:59 AM

How long does this happen? Problem with glow plugs would occur in the first minute or so, after that the engine is independent of the glow plugs so if there is still an issue after that, there's another problem. I'd at least run a diesel purge.
Mine was idling badly when cold so I did a valve adjustment and diesel purge. Now it's much better.

barry123400 · #6 01-22-2007, 12:02 PM

Retarded injection pump timing could cause excess smoke as engine cannot really sustain good combustion when cold. Smoke should be blacker rather than blue though. Just to check it is not hard. You need an old injector line to make a drip tester basically. Only if it is way out go further. I believe it should be done on any new aquisition including a chain stretch test. The pump cannot move itself. If injection pump timing is way out it has to be excess chain stretch usually. The primary flaw in what I suggest is that a retarded timing usually causes the engine to be a little harder starting than the same engine timed right. Your statement that it starts right up is not particularily condusive to checking it. On the otherhand your current misery is not going to go away itself unless you have a load of bad fuel so why not do a quick check? You would not want to do a lot of things and eventually end up back at the initial pump timing. Of course the above standard size bubble in the primary fuel filter means you could check for air getting in as well I guess. You could also look very carefully to see if small air bubbles are working their way through the primary fuel filter as well. Although an air leak could be past that point as well. Your description of events has been noted reciently with a badf secondary fuel filter as well it seems. You have changed that already. Although I am not sure how it actually causes the effect. . It could also be a combination of a couple of deficiencys.

toomany MBZ · #7 01-22-2007, 07:07 PM

I understand that GP's only work when the dash light is on. Try a purge, can't hurt, then perhaps a compression check.

winmutt · #8 01-22-2007, 07:12 PM

At this point I'm inclined to believe it is the GPs. Parked at work today (indoor heated) and car started on point and had no hesitation.

Stevo · #9 01-22-2007, 09:35 PM

Check them and if there are a couple bad ones I would replace them all and keep the good ones for spares, you dont want too get stuck someplace this time of year with bad GPs

winmutt · #10 01-22-2007, 10:38 PM

Quote:

Originally Posted by Stevo

Check them and if there are a couple bad ones I would replace them all and keep the good ones for spares, you dont want too get stuck someplace this time of year with bad GPs

Well its still pretty warm down here

. The light goes out as it should. I suppose I need some jumper cables ans some good gloves?