300D dies at idle, hard starting. - PeachParts Mercedes-Benz Forum

bdgr · #1 06-28-2007, 03:24 AM

Fairly new Benz owner here. I have a 1983 300d, when I bought it it started immediately with no pedal every time, ran great, pulled out really well and generally was a blast to drive.

I ran one tank of B20 through it and discovered that the gauge wasn't quite accurate while it still said I had fuel it appears to have run out. I put in fuel and primed it with the manual pump and it did start but I have been having problems since.

It usually wont start cold unless I hold the pedal all the way down. Once it starts, it barely runs, no power for a bit until I get it moving. Once it moving it starts to pull out again and does fine on the highway. After it warms up again it's hit or miss. Some times it runs like it did when I first got it, other times it dies at stop lights and takes for ever to get moving again...then everything will bo ok.

I've replaced both fuel filters and I can see fuel getting into the first filter.

Ideas on tings to try next?

vstech · #2 06-28-2007, 09:41 AM

pull the spin on filter and verify you have fuel to the top.
put that back, then verify while cranking it, open each line nut and verify you have fuel squirting out each injector nut AT the injectors. where did you get the bio? bad batches have been known to damage IP's but you would have to have really gunky fuel and you would see it in the clear prefilter.
also possible is the tank screen in your fuel tank is plugged up. and also your vent screen in the passanger's rear wheel well could be clogged up with dirt. try driving with the gas cap loose, and see if it improves.

bdgr · #3 06-28-2007, 10:12 AM

Quote:

Originally Posted by vstech

pull the spin on filter and verify you have fuel to the top.
put that back, then verify while cranking it, open each line nut and verify you have fuel squirting out each injector nut AT the injectors. where did you get the bio? bad batches have been known to damage IP's but you would have to have really gunky fuel and you would see it in the clear prefilter.
also possible is the tank screen in your fuel tank is plugged up. and also your vent screen in the passanger's rear wheel well could be clogged up with dirt. try driving with the gas cap loose, and see if it improves.

Thanks for the reply.

got the Biodiesel at DFW Biodiesel, they are pretty repututable around here..problems didn't start until I ran out of it, so I'm thinking thats not it.

Tried driving it today with the gas cap loose, no change...but it died completely for a bit and when I checked this time the filter was empty. Pumped the manual pump a few times and it filled up and then I managed to gradually creep..and I do mean creep up to speed. By the time I got home it was running and idling perfect. I'm thinking your right...it's probably the screen plugged up with stuff the bio loosened up.

Do you have to drain the tank to clean the screen?

vstech · #4 06-28-2007, 10:47 AM

empty prefilter? that sounds like a leak in the fuel line. check under the car near the fuel tank for wet lines. also check near the firewall for line leaks.
www.dieselgiant.com has a write up on replacing fuel lines, use that pictorial as a guide to find the leaking lines. hope it's not a steel line rusted through!

bdgr · #5 06-28-2007, 02:58 PM

Well...Maybe. I just found a leak, but it was the hose between the pre-filter and the primer pump. I replaced that piece of hose, and primed it..the filter immediately filled up with fuel. before when I disconnected that line the fuel continuously ran out, but this time nothing came out until I used the pump.

The car started immediately and idled like it should, about to take it for a road test but while I was under there I noticed something...

There is one of these:
[IMG]http://www.***************/secure/PartImages/0015407097.jpg[/IMG]
(at least it looks something like that)

On the firewall but there are no vacuum lines hooked up to it(there appears to be an electrical connection to it). Should this be hooked up, and if so to what?

vstech · #6 06-28-2007, 03:26 PM

that is the infamous overboost selanoid. it should be hooked in the line between your alda and the banjo bolt on the intake manifold... mine is unhooked too... it protects the car from over fueling....

bdgr · #7 06-28-2007, 03:38 PM

Quote:

Originally Posted by vstech

that is the infamous overboost selanoid. it should be hooked in the line between your alda and the banjo bolt on the intake manifold... mine is unhooked too... it protects the car from over fueling....

Well...As of late there no danger of OVER fueling...

Ok, so it's ok to leave it out of the loop?