My 1982 240d recently started consuming excessive fuel (below 20 mpg) and the engine runs harder (higher rpm's) than before. I did the diesel purge/fuel filters and drained the fuel tank to replace the screen. No change. The engine starts and idles fine--just seems like about 75% of power being transferred to the drive train. Low gas mileage because I have to run it harder just to reach normal driving speeds.

I then noticed my hand primer pump is leaking, and I have never changed any of the injector hoses. Could the air leaking into the fuel system cause the high rpm's and low gas mileage?

BTW-the tranny and torque converter seem fine, and I have no vacuum or linkage issues. The tranny fluid/filter and oil are fresh.

Thanks. Any suggestions are appreciated!

 

You will leak fuel out of the hand pump, that could explain the higher fuel consumption. The return lines will leak fuel as it has a little pressure and not vacuum so I don't think you could get air in them without noticing fuel loss from there. Higher RPM can only be traced to your transmission. There is no way to increase rpm without increasing speed unless you are slipping or changed gear ratio's. 240d doesn't have a tachometer at least mine didn't and I haven't seen one from the factory. How sure are you that you are raising rpms without going faster just sound?

 

Yes-I drive the same 7 mile freeway every morning, and the engine is full blast just to maintain 60 mph on a flat road.

Transmission doesn't seem to slip and shifts pretty smoothly. Wonder if the torque converter isn't locking or isn't coupling correctly. I am just a weekend mechanic and have no experience diagnosing torque converter problems.

Thanks.

 

Are you sure you still have all gears? Top speed for third is right around 60mph.

 

It shifts into all 4 gears.

The more I read, the more I think the tranny is slipping. It also has made a couple of short "squeals" recently when cold and shifting from 2nd to 3rd.

Probably made a mistake in changing my transmission fluid--should have left the gunk in there for friction. No good deed goes unpunished