1985 300TD Wagon - PeachParts Mercedes-Benz Forum

BigRed0803 · #1 01-09-2009, 08:02 PM

I just got a 85 300 wagon. I am having problems with fuel delivery I suspect. When driving the car around town or on short trips everything is fine but when taking a long trip after a while the car will just start losing power. It is so bad I have to pull over. I can turn the car off and let it sit for a minute or two and the car will do fine for another couple miles or so til this happens again. This turns a 2 hour trip into a half a day journey. I have changed both fuel filters and have also cleaned the tank strainer. I bought the car thinking one of those things would take care of the problem but it did not and now I am stuck with the car. Does anyone have any idea what could be causing this? Thanks

uvula · #2 01-09-2009, 08:14 PM

How many miles are on it? Does it smoke more when you lose power? Do you live in a cold or warm climate?

BigRed0803 · #3 01-10-2009, 11:46 AM

The car has 242,xxx. It doesn't smoke anymore than normal. I live in western NC. Any ideas?

JimmyL · #4 01-10-2009, 11:54 AM

I was thinking filters and tank strainer right up until the time you said you have already replaced them.
I guess you could have air in the system, possibly from a leaking primer pump. Seems like that usually affects starting though, not necessarily running. Even more likely might be your lift pump. Have you tried test driving without the fuel cap. [almost said gas cap]

I think that is unlikely, though.
I'll let the smarter folks in this area chime in.......
Kudos on proper reference to your wagon [300TD]

Bio300TDTdriver · #5 01-10-2009, 12:04 PM

Do you know the fuel history of the car? Has it burned WVO? Has it burned Biodiesel? How do the fuel lines look?

Chad300tdt · #6 01-10-2009, 12:08 PM

When you cleaned the tank strainer, how gunked up was it? Did you flush the tank?

The symptoms you describe make me think that gunk in your tank is collecting on the tank screen and settles off when you sit for a while.

Another thought ... Check out the condition of the fuel lines. Mine rotted under the subframe. They rotted just enough to let air enter the lines when running and the car would act like you're describing. Once the lines rotted enough to actually drip diesel, I discovered the problem and replaced the lines with rubber "diesel rated" fuel line. I left the hard line in place after I cut the bad section out and used it as a bracket to zip tie the rubber lines to.

EDIT: I see Bio300TDTdriver had the same idea.

mobetta · #7 01-10-2009, 01:52 PM

you could switch the supply and return lines under the hood to eliminate the tank screen as a problem- but dont run it much under 1/4 tank that way.

I recon you should check for air leaks though.

OldPokey · #8 01-10-2009, 03:46 PM

Quote:

Originally Posted by Chad300tdt

Another thought ... Check out the condition of the fuel lines.

Ditto - mine were rotten - but only so air would get into the system without letting fuel out. However, your probably wouldn't be able to prime the system after replacing the fuel filters.

mobetta · #9 01-11-2009, 04:07 PM

I had my fuel line rot out, too- I found it by pressurizing the tank slightly with a shopvac. it was above the subfame, so I "temporarily" ran new fuel line front to back. used the blue clear poly stuff. been fine for almost 3 years now.

TchTchr · #10 01-11-2009, 04:23 PM

Quote:

Originally Posted by mobetta

I had my fuel line rot out, too- I found it by pressurizing the tank slightly with a shopvac. it was above the subfame, so I "temporarily" ran new fuel line front to back. used the blue clear poly stuff. been fine for almost 3 years now.

Where would one get the "clear blue poly stuff?" I'm going to try this on mine the next couple of weeks.

Chad300tdt · #11 01-11-2009, 04:23 PM

Here's the thread I did when I put the rubber lines in, so you can see what I mean about using the hard lines as a bracket.

Good luck.

Leaking fuel lines repaired today