Help and Hello :-) - PeachParts Mercedes-Benz Forum

Duelten · #1 03-07-2004, 10:45 AM

First post here...this site looks pretty cool.

If this has been covered before...please accept my appologies...I'm in a pickle.

My 1981 300SD worked fine in the morning...then in the afternoon....on the way to pick kids up from school....it slowly lost power, like it was starving for fuel. Had to depress the pedal farther and farther....

Then it died. Managed to start and get to curb. Now it won't start..(towed it home) and I think it sounds like a fuel pump problem...but I'm no mechanic and diesels I'm totally a noob.

I did replace a little clear filter and another that looks like a small oil filter...no help.

I bought a chilton manual, but the information is schetchy at best...I tried to find the fuel pump underneath the car where the book suggested, but alas...I don't see it.

Can any one help with the location of it? Troubleshooting tips?

Can I get the pump off the car easily? Is it likely the problem?

The car has over 200,000 miles on it so perhaps its time for an new pump.

Appreciate any help.

suginami · #2 03-07-2004, 12:31 PM

You would probably get more response if you re-posted this in the Diesel section.

It's by far the most active forum on this site.

Duelten · #3 03-07-2004, 12:36 PM

I was wondering about that...I'll do it.

Thanks.

stevebfl · #4 03-07-2004, 01:44 PM

I have seen a couple common problems. Most common is algae growing and dying in the fuel tank. There is a screen with large holes at the exit from the tank. This coats and plugs with the gunk. Had two just this week.

We take the tanks out and steam clean them.

The other common problem on high mileage motors is in the fuel feed pump. I have never seen the pump itself fail at any mileage, but there are plastic check valves in the inlet and exhaust of the pump that do fail causing the pump to just push the fuel back and forth. The pump itself is mounted to the injection pump on the fender side close to the front. The fuel line from the inline filter attaches to the feed pump. The other side goes to the larger oil filter looking filter. To get to the check valves, take the fuel lines off the pump and keep removing the fittings the fuel line attaches to. The bottom one is 22mm if I recall and the check valves are underneath.

Duelten · #5 03-07-2004, 01:59 PM

Great info! Um...is that the thing with the manual pump that I can unscrew and pump air out of the lines?

Thanks stevebfl...I'm off to check that now!

Also...is there anyway to check somehow if the fuel is actually getting to the injectors? Perhaps my Injector pump is bad?

Just a thought....

stevebfl · #6 03-07-2004, 02:34 PM

Yes the hand pump is mounted between the two fitting I am talking about. Some diagnostics can be gained from attempting to hand pump the fuel. If you pull up a stroke and it pulls right back your are restricted. If your pumping seems to grab nothing then the valves are one possibility.

Duelten · #7 03-07-2004, 02:42 PM

OMG!!!!

It fired up! It actually started!

What should I do now? Should I add some additive in the gas tank to help clean the tank/fuel?

I'm not a weirdo...I'm happily married, but doggone it you have made may day...heck..you've made my year (its been a rough year with family members dieing and a new move)....I could just hug ya!

WANT '71 280SEL · #8 03-07-2004, 04:17 PM

Did you have to loosen the bolt to purge the air out or just pump it?
Thanks
David

P.S.
Feels good, don't it?

Duelten · #9 03-07-2004, 04:21 PM

I had to loosen the bolt and pump til some fuel came out.

I tried the chilton manual way and pumped with the bolt tight and listened for a "hiss" of air...but that didn't work.

The loosening of the bolt and pumping worked fantastic!

P.S.

Oh gosh yes! It feels more than good! I've been in a tight spot with worry and bills after moving across the country with my family...this was a bad time for one of our cars to break down...I'm just so happy I found this site! You've no idea!

cbdo · #10 03-07-2004, 05:23 PM

I'm absolutely no expert on MB diesels, but diesels in general are very fussy about air in fuel lines, and need to have the fuel lines bled if they've been opened at all or if there's been air introduced in any other way. Was that what actually worked here?

WANT '71 280SEL · #11 03-07-2004, 05:31 PM

yes, he stated in another post that he had lost power and so replaced both fuel filters. Thus opening the fuel lines. He had to use the hand primer pump to purge the air out and now it runs like a Mercedes-Benz.
David

Duelten · #12 03-07-2004, 05:33 PM

Not exactly sure.

It lost power and then died with no air introduced here...perhaps bad fuel? The fuel was low and it was cold. I did then change the filters and add more fuel, which probably indroduced the air.

I was thinking fuel delivery problem until someone suggested pumping out the air in the correct manner...then it worked. Started like a champ as it had before...and ran great! It does smoke as always..but from browesing these forums I think perhaps that is a glow plug replacement. Dang I'm loving these forums! Great find!!!

I'm so happy right now I could just float....

cbdo · #13 03-07-2004, 05:36 PM

I have fond memories of purging the lines on a Perkins 6-cylinder on one of our boats, which was *not* set up with a hand pump as the MB is. The manual gave the procedure, then gave one backup refinement in case it still didn't run, and then said in classically British manner, "If the engine still doesn't start, we suggest you look to the contents of your signal locker."

Duelten · #14 03-07-2004, 10:28 PM

LOL

Bruce B · #15 03-08-2004, 12:23 AM

And if ya can't find it in the "signal locker" (flare gun) just wave your arms wildly....lol. I couldn't resist that, I own a gas burner but drive a diesel truck for a living and Friday AM while on the way to a job BOOM, clankity clank. Had to put it on a hook and take it to the Mack shop. Hope it's just the Jake Brake. I've seriously considered looking for an oil burner as my next Benz, even the very high mileage ones still run good.

Thanks for letting me share