I'm trying to find out the cause of my poor mpg on my 1992 300sd. I replaced the o-ring seals on top of the injector pump. My mpg was great for about a week, and then went back to poor mpg again. Could bad injectors cause poor mpg? I looked closely and don't see any leaks on the pump or around the injectors thanks. I don't know if it's related but my fuel cap is rusted out not sure how that happened.

What do you call poor? What do you expect? My 1995, S350 is getting 20.2 mpg. Expected 22-23.

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Present
1987 300SDL
1991 300SL
1990 560SEL
2001 ML320

Past
1969 200D 1979-82
1983 300SD 1984-85
1972 250C 1982-02
1995 S350 2011
1997 S320 2012

have you run a Diesel Purge through it? Done an Italian Tune? how does the engine run? Poor idle low power?

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hum.....
1987 300TD 311,000M Stolen. Presumed destroyed

Not to hijack but I have an Ijector pressure line leacking on top of the in flare nut. I believe I need a new line and/or injector. It runs like crap when it that one us not firing but is noticeably good when it happens to start firing. Any ideas on the best place to get lines?

In the past I have advised that int the past large Fuel Injections Shops used to make Fuel Injection Tubings. However, no one has ever said they found a shop that would do that.

That only leaves the Mercedes Dealer.

Also if all of the Clamps that keep the Fuel Injection Tubings from vibrating are not there or are in bad contidion it will or another Tubing will break later. The Clamps are more Dealer items.

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84 300D, 82 Volvo 244Gl Diesel

You can also try the parts section here for a new tube. someone may have one.

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hum.....
1987 300TD 311,000M Stolen. Presumed destroyed

mpg great for a week sounds like a measurement anomaly unless you drive at least a thousand miles a week.

Sixto
87 300D

X2 on the clamps. A full set is absolutely necessary if you don't want your tubes to crack or rub holes in one another. Use EPC as a guide and make sure you get every one. Not cheap, though, a dealer is about the only source for new ones while the used ones at the junkyard won't be any good unless they were changed just before the car was wrecked. I spent something like US$100 putting together a complete set from my dealer as almost all of mine were missing thanks to the PO.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Thanks for your input guys, i'm gonna take some time and have a closer look soon. Possibly take a hammer to it

And yes injectors can cause poor fuel economy.

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1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

Thanks, I replaced the line and it still leaks, I believe the injector is cracked. Iwill look for a new injector now.


Used dealer for line due to time coNstraints. Not cheap of course. 65 smackers.

Injectors can leak between halves. You can clean the injectors yourself -

http://www.peachparts.com/shopforum/showthread.php?t=299321

The injector innards can use a cleaning and the set pop tested and balanced if you're pulling the injectors. You can make the investment in tools or take them to a Diesel shop. Don't forget new timecards.

Sixto
87 300D

It's been a couple years or so on my Monarks, I want to check pop and pattern. And finally I have a compression tester... so I'm doing that too.

But, my question related to this thread, is it OK to soak assembled injectors with tips in carb cleaner and use a brass brush to remove carbon. Then more pop testing to flush the fluids out... and drop them back into the car?

thx

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Cheers!
Scott McPhee

1987 300D