Poor Gas Mileage
 

I have had my '84 300D for about a year now and have never gotten very good gas mileage. I have tried just about everything imaginable to rectify this, to no avail. I have repalced fuel filters, air filter, tried diesel additives, adjusted valves... Every now and then I will get 21mpg on the highway, but most of the time I get around 19-20mpg. Driving daily on the freeways, it is much worse. Any further advise to raise it up a little would be appreciated.

Mike

Have your injectors checked ... and while they are out.....
pull your precombustion chambers and inspect them.....

if my injectors were bad, would it idle rough? I would also think they may be nailing a bit if they were bad too. She runs like a champ with lots of get up and go. At idle she is smooth as silk and doesn't make any funky noises.

Mike

Mike, that is low. My 1984 is also low, but manages to get 23-24mpg most of the time, mostly freeway, or 21-23 in the city. That is below what it SHOULD get, which is 25-30 (city-freeway). There are a zillion things to check - use the "search" feature and you'll find numerous other threads on this topic. Wouldn't hurt to make sure the brakes are not dragging at all - should spin freely. Otherwise it could be the injection pump, over-tweaked ALDA, way retarded IP timing, or a number of other things...


Good luck,

Sublettm,

I know what the problem is causing the poor GAS mileage: You should be using Diesel fuel.

P E H