79 300SD ran out of fuel, now won't start - PeachParts Mercedes-Benz Forum

neurot · #1 10-04-2006, 01:11 PM

My fuel gauge is broken, so my girlfriend ran out of fuel. This has happened before, and a 5 gallon container and a few minutes of cranking has always worked. This time, however, it will not start. I even tried starter fluid, which does create a little different sound, but it will not catch. I use biodiesel, and have ASTM certified B100 splash blended down to about B60 (60% biodiesel, 40% petroleum diesel). I have replaced the fuel filter, pumped the heck out of the manual lifter pump, and checked the vacuum lines. I also opened up each of the injectors and cranked it - when doing this, it appears that no fuel is going through the lines. the rear two have a little fuel dripping, but not much, and the front 2 or 3 have nothing coming out. I'm afraid it's the injector pump itself, but not sure how to troubleshoot it. I do have the big service manual, and the Hayne's book, but not finding much practical how-to information.

Any ideas of what I can try next?

thanks!

Jason Burroughs
1979 300SD with 85k miles

stcbenz83 · #2 10-04-2006, 01:13 PM

could it be a clogged tank screen?

MattBelliveau · #3 10-04-2006, 01:15 PM

Running out of fuel runs the possibility of all the sediment in the bottom of your fuel tanks running into the tank screen, clogging it. I would assume this is your problem. Do you know where your fuel is going (ie, confirm that fuel is getting to the prefilter, then to the other filter, then to the motor (injector lines)). If you are running dry somewhere before the IP, your tank screen is probably at fault.

MattBelliveau · #4 10-04-2006, 01:16 PM

And another question. Where the hell does someone find such a jem with such low milage. A pretty penny must have spent for that car!

vstech · #5 10-04-2006, 01:17 PM

Try loosening the spin on filter bolt, then pumping the heck out of the manual pump until you get fuel out the filter, then tighten the bolt, and loosen the banjo bolt going into the IP and continue pumping and pumping until you get clear fuel at that point.then pump and pump... cranking without fuel can damage the IP, so only crank the engine after you have fuel out the IP banjo bolt... good luck.

John

neurot · #6 10-04-2006, 01:51 PM

thanks for the quick replies. i'll follow the instructions about the input to the IP and all the pumping.

about the tank screen - where is that and how can i check it out?

david s poole · #7 10-04-2006, 02:29 PM

ok get access to compressed air.diconnect fuel line at the prefilter[at the injec pump].now remove fuel tank cap and blow compressed air backwards to tank.you should be able to hear bubbling.now go to gas cap hole and using shop towels to help plug the hole pressurise the tank with comp air.if the screen was blocked you just cleared it.you should now have fuel coming out at the pipe going to the prefilter.hook back up and keep tank press while someone starts the car.voila! you have cured blocked tank screen[common when you allow girlfriends to run car out of gas].

neurot · #8 10-04-2006, 02:47 PM

it appears that in all of our line purging, we missed the one line that goes from the fuel filter to the far side of the injector pump (between the engine and injector pump). I'm not sure if that's THE input to the IP or what comes from the return lines from the injectors, but after I loosened that banjo, did some pumping, then retighted it, it took several minutes and finally started up!

After spending more than a few hours on this over the past couple of days, I was about to tow it to the shop - so I owe you all!

Jason in Austin (thanks David for the tip about the tank screen - may have to use that next time!)

vstech · #9 10-04-2006, 03:15 PM

Quote:

Originally Posted by MattBelliveau

And another question. Where the hell does someone find such a jem with such low milage. A pretty penny must have spent for that car!

yeah, I second this request!

neurot · #10 10-05-2006, 11:36 AM

Oh, I forgot to mention...I paid $4500 for it. It actually has an interesting story. The first owner did something to damage the engine after 40k miles. Then it sat for 10 years, and was sold to someone who spent about $7000 rebuilding the engine, replacing suspension and about a million other parts. That person sold it at a big loss to the person I bought it from - who also spent a lot on new parts, including a paint job to factory red color. So, it actually only has 45k miles on the rebuilt motor, 85k total miles. I have replaced the fuel lines with viton hoses, run B100 since I bought it, put on 4 new tires and got an alignment, and did usual preventative maintenance work (just did the glow plugs, air filter, fuel filter, power steering fluid). However, I need something smaller to fit into my carport that I'm converting into a garage, and this gem is up for sale!

I don't have any pictures of it where i'm at, but the interior is in excellent condition, no rips in any seat, one small crack in the dash, A/C is COLD, cruise control works, aftermarket CD player (still have original radio and speakers to go with it), seat very firm (has not been rebuilt).

Things that need work: my girlfriend scraped one side of it, knocking the trim off the back right door and causing a slight dent. Paintless dent repair says they can ease it out with no problem, but it needs to have that door repainted. It also has a slight coolant leak in the heat of summer that I haven't spent time to fix, and the rear driver window does not go up quite all the way (about 1/2 inch down - even in heavy rain, it did not get wet inside). fuel gauge sending unit in tank does not work, so it always says it has 3/8 of a tank.

If anyone is interested, I'm looking to get back what I have into it, which is around $5000 - minus something for the side work. I will take lots of pictures if anyone wants to see it.

Note, the vehicle is in Austin and I will be glad to arrange shipping.

Thanks!

Jason