I my 83 DT has so little power that it will barely run 50 mph and takes minutes to get there. I have to floor the accelerator to get it to start.

It seemed to be sucking some air, I replaced everything from the fuel tank to the injection pump. I still notice some bubbles in the prefilter, but they are small and not that many. I replaced the primer pump, (it was leaking)
I replaced the firewall mounted part of the throttle linkage (it was broken). My mechanic adjusted the valves. None of this had any affect.

A local mechanic thinks it is the IP. It took him 2 months to decide this. The car runs and idles fine but obviously isn't getting enough fuel. I revs slowly.

3 questions:

1 How much air does it take to affect power?
2 I have read that the auxiliary fuel pump under the primer pump might be a problem. (how do you test it for pressure?)
3 Is there a test the a home mechanic can do to test the IP?

Any other ideas?


I have been messing with this problem off and on for close to 5 months

Thanks Ben

That is the Fuel Supply/Fuel Transfer pump not an auxiliary/extra fuel pump under the primer pump.
Putting a pressure gauge between the filter and the out let of the Fuel Supply pump and measure the pressure.
See post #3 for some specs.
Transfer pump pressure

There is also a part called the Overflow Valve that is on the opposite side side of the IP
Some info on the Overflow valve is found in this thread but ignore the title of the thread.
Fuel pressure relief valve adjustment

Have you tried running your car with the fuel inlet hose in a separate container of diesel fuel?

__________________
84 300D, 82 Volvo 244Gl Diesel

OK Ben. Walk to the back of the car. Look at the trunk lid. Tell me if it doesn't just say 300D. Still haven't seen one yet with the elusive "T" on there also........

__________________
Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

300Ds are often listed as 300DT by internet part sellers or some times they are listed as 300D Turbo. And, some sellers will also list a wagon as 300TDT.

That useage does not make it correct but it is easy to see how someone might end up using the term.

__________________
84 300D, 82 Volvo 244Gl Diesel

MB America uses the term also. Jimmy and I have had this exchange in another thread. LOL I'll bet the badge for my american sold 83 300D (with a turbo) came out of the same parts bin as the one they put on the European 300D (non turbo) in 1983. Even my original window sticker, printed by MB reads 300D-T.

Anyway, back to your question: I had a similar loss of power as I wore out the ball connection on the accelerator linkage. Mounts to the firewall. If it's worn enough, the linkage will not fully engage the full range of motion to the IP.

__________________
Charles
1983 300D, bought new, 215k+ miles, donated to Purple Hearts veterans charity but I have parts for sale: http://www.peachparts.com/shopforum/mercedes-benz-cars-sale/296386-fs-1-owner-83-mb-300d-turbo-rebuild-parts.html

I have four questions, myself:

1) Has the mechanic checked IP timing?
2) Has the mechanic checked for chain elongation?
3) Has the mechanic checked for boost and for a functioning ALDA?
4) Has the mechanic checked to be sure the throttle linkage is adjusted properly and is fully opening the rack on the IP?

Ask the "mechanic" these four questions.

If you get a stupid look out of him...........immediately remove the vehicle from the premises.

The problem is almost never the IP.

Did you clean the tank strainer? My car did the same thing and it was fuel starved.
Is that throttle linkage correct?

__________________
Think Alternative Energy!
300CD '80 (now gone but not forgotten...)

Not trying to start anything but my Nevada DMV title say 1987 Mercedes Benz 300 DT not with any input of mine just off the computer system by Vin #, i know this does not make it correct/incorrect or imply that MB intended it to be that way...i can just see how people can get miss led without proper education i guess.....education from (JimmyL)...

Oh and my trunk says only 300d on the left

ARLO

sorry for hijack

Maybe not necessarily in that order.......

I know others get the terminology wrong. Don't let that influence you to do the same......

__________________
Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

Jimmy is now Skipper? Has Jimmy told Captain Monk yet???

__________________
RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

I am not quite sure what the mechanic did. He checked the valves and apparently did start it using a fuel line connected to a can of fuel. I replaced the filters (twice) all fuel lines, strainer, primer pump, ball joint in on the fire wall, checked the adjustment of the accelerator linkage, (it appeared to be OK). I really don't think they checked that pump timing. This happened suddenly, I didn't mention that. I also replaced the shut off valve. The problem started about a week after that.

It ended up being the fuel injection pump, lucky me. I got a used one installed to the tune of $1000. Took a year to find the right mechanic and for him to find a pump he was comfortable with. He tested the pump by moving turning the screw on the injection pump that controls the shaking (I forget its name). He noticed that it had no effect on the pump. I think the real clue was that it happened so quickly. The engine ran fine and then didn't.

WOW great response time with the problem and solution! Thanks for finishing the thread and letting us know what the issue was.
IF you had continued the thread, and given us the problem, we could have gotten you an IP a tad faster...