Excessive fuel consumption

[eamo]

Hi Guys

Just bought a 1990 318i as a run around. Have it 2 weeks. Fuel consumption was as it should be.

Diff went in it last Friday so I changed it. IT was a 4.10 open diff so I put in a diff from an 89 316i which is 4.27

Now however fuel consumption is mad. I get about 30 mile to a tenner!! Surely it cant be the diff that made the difference.

I had the car over a pit to check for leaks etc and couldnt find anything wrong. Any ideas??

[Martinaston]

hardened and cracked fuel lines that run under the inlet manifold ?

[KiwiCarl]

I've used 4.45, 4.11, 3.64, 3.46, and 3.25 ratios in my car and I can definately say that there's a direct correlation between the higher the ratio the higher the fuel useage.
I also found that with the car being more rev happy with the higher ratio diffs my foot was more heavy...

[eamo]

re the ratios - yes if one had gone fom a 3.15 to 3.9 then definetley you would see increased consumption. I did this before in my evo 2 m3.

with my cecotto i went from 3.25 to 3.64 and again consumption increased but not as dramitically as when i had the evo2.

I cant see however how going from 4.1 to 4.27 would have the effect im expieriencing.

I'll put it back up on a ramp and have another goo at it in a few miuntes