The only way to determine mpg is to keep a fuel log. Miles per tankful is not an accurate number. My '83 TD (4 speed conversion) gets 27 beating around town and over 30 on the highway - if I can keep it under 85mph. - Jacob

Can you show me how you do it? Maybe not show but can you expalin further.

__________________
1984 300D/T (sold)
1981 190D 2.2 (sold)
1989 300E 142675 miles (sold)
1981 300D 254+++ miles (current)
Q.C. Autosports Philippines (est. 1965)

Each time you fill up the vehicle, you fill it right to the cap.

Make a note of the fuel used and the odometer reading in a log.

After 10 fillings, you have the total amount of gallons used (say 170 gallons) and the total amount of miles driven (subtract most recent odometer figure from original figure) and you get 3740 miles. You have a solid data base (10 fuelings) and can accurately state that you are getting an average of 22 mpg without the error of an individual fueling stop.

The more data you use for the average, the better and more reliable the number.

If you fill it up to the cap everytime, your data should be pretty accurate without needing to average it out over so many tankfuls. But if you want to average it over your different driving conditions, then i guess you need the extra data.

I fill mine to the cap every time. I can add almost two gallons after the pump self stops. I do wonder how much capacity the filler neck holds.

I'm also amazed that I don't get fuel foaming when filling my MB's. When adding diesel to my 6.5TD Suburban, I get lots of foam, which makes it slow and tough to fill fuel to the cap.

__________________
1970 280SE Cab
1983 300D Euro 4-speed
past MB's:
1971 280SE 3.5 s/r
1981 300D
1985 300TD
1987 300TD

about filling to the cap. too slow. i just fill it the same place pretty much all the time and let the pump shut itself off.

fill, drive it keep track of miles fill again. whatever the second (and so forth) fill is divide the miles by the gallons and get mpg. for better accuracy average more fills.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I'll do that.
Is it hard to do the injection timing. The way I see it in the book, it seems so easy. I actuaslly do everything myself being a mechanic and an engine builder,but new in the diesel world.. But I see that the basics are the same, just the difference in fuel management. I just need advice from you guys. I would really appreciate all the help I can get from the nice people here.

__________________
1984 300D/T (sold)
1981 190D 2.2 (sold)
1989 300E 142675 miles (sold)
1981 300D 254+++ miles (current)
Q.C. Autosports Philippines (est. 1965)

That sounds the same as ...SPEND MORE MONEY

__________________
1984 300D/T (sold)
1981 190D 2.2 (sold)
1989 300E 142675 miles (sold)
1981 300D 254+++ miles (current)
Q.C. Autosports Philippines (est. 1965)

but call me mr obvious but i dont get it?

how am i spending more money? or if it is a joke i still dont get it.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I was just joking. hehehe...
well, I'll follow your advice about logging things every tank full then, compute.

__________________
1984 300D/T (sold)
1981 190D 2.2 (sold)
1989 300E 142675 miles (sold)
1981 300D 254+++ miles (current)
Q.C. Autosports Philippines (est. 1965)

but i still dont get it.

that's ok i often don't.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

It is and it isn't some times. The IP on my 115 has given me a lot trouble in its days (months) I've had it. Mine doesn't push fuel all of the time or if I take the spring out it pushes fuel the whole time. I have done it about 4 times and I still don't have it right. I even had a freind help who just did his 123 and my pump didn't behave the same. But it is suppossed to be easy.

The small adjustments are really easy, but if you have to do pull it out (which you won't that is a lot of adjustment) on a 115 .....NOT FUN.... a 123 probably a little easier.

Look up on the search...there are a couple posted articles on how to time your IP.

__________________
76 300D 130K "Stella" (Sold )
74 240D 299K (Donated to Highschool For Senior Project WVO)
83 300TDT 290K (My one and only)
Sanford, NC

My 240D gets 32 on summer fuel and 27 on the winter fuel. Can't beet the old 4 cylinder. With the 4 speed, I think it runs almost as good as the 300d turbo.

DIESELNATION

__________________
82 240D - 257k
84 300d - 86k

You are breaking my heart...
...but thats ok...I think I'm on the right track. I wish someone would shed more light on the injection pump timing issue. And does anyone have a vacuum diagram in the egine bay area (from vac pump going to the tranny and to the other parts), that will really help and the number of chckvalves...HELP!

__________________
1984 300D/T (sold)
1981 190D 2.2 (sold)
1989 300E 142675 miles (sold)
1981 300D 254+++ miles (current)
Q.C. Autosports Philippines (est. 1965)

I have the same problem with my '84 300D. I only get 21 mpg. I had an '81 300D non-turbo that got consistently 32mpg ( I drive them both the same). My '84 300D's fuel pump linkage is sticking now...don't know if the bad mpg was a result of a bad pump. When I put it in park after driving it a bit it idles erratic ( not too bad though). I can now go barely 10 mph and then when it does build up power it takes off and and i take my foot off the accelerator and t continues to speed up. I'm saying all of this to say that I feel your pain and don't know the answer. If anyone has a diagnosis let me know it will be greatly appreciated . By the way, I cleaned the banjo bolt twice, adjusted the valves, even tried tweaking the ALDA ( which I think I messed up), put a new primer pump (new type) because the old one was leaking. If you don't have any advice...prayer would be greatly appreciated (Js 5:16 the effectual fervent prayer of a righteous man availeth much).

Basically your model should give you reasonable fuel consumption, depending on load, conditions(driving), correct computations, and say for arguments sake that you are getting 20mpg under your 'usaual/simmilar' driving conditions, which I dont doubt, you are correct and have done all the simple things like tyre preasures etc, could I suggest you try the following (in order would be best) & if no luck then get back to us & we will sort your problem out.

1 - check your air filter for serviceability
2- check all air ducting (air intake) & trumpets & connections to the engine for deterioration, damage loose fitting etc
3 - place your hand over the air inlet, where it easy to get to, and with motor running, choke the inlet briefly with the flat of you hand, the motor shoud seem to wanto start dropping RPM quickly. If this happens then you know the intake side of the motor should be Ok, if no change in RPM you will neeed to do further testing (like inlet manifold gaskets leaking) etc.
4- check your exhaust system for, any sever damge to pipeing etc, and the mufflers for contrictions/leaks etc. Take your time & be thourough. you may have to get the exhaust system checked by a suitable workshop.

We need to detemine if the motor is breathing and exhausting as per specs.

5 - I know they not cheap, but suggest you renew all fuel filters. Blocked or clogged & well...., also the vechile is 2nd hand and without a comprehensive service history, you probably find that filter replacement & bleeding is needed. this will also cover the problem of excessive air in the fuel delivry system.
After this we will have to dig deeper into Compession testing, fuel pump delivery volume /preasures, but we need to have checked the 1 - 5 first.

Good luck & let us know whats happenes

Graham