I know functionally nothing about modding or coding but I poked around in the LUA and found the fluid consumption rate and efficiency modifiers for the diesel generator. If the efficiency is dialed back to like 10% (0.10) and the fluid consumption rate is like 5 per second (5/60) these actually run a little bit more realistically so you can't run 100 generators on a drip feed of diesel fuel. Additionally, setting the maximum power output to something a little less overpowered than 4MW helps too. I set mine to output at a maximum of around1.6-1.8MW and I think it makes these a lot more balanced.
For those interested, if you open the mod archive and go into /prototypes/diesel-generator.lua (you can open this with default ol' Notepad) you'll find the values to tweak to your liking under "max_power_output =", "effectivity =", and "fluid_usage_per_tick =". There's a lot of trial and error here with changing things, loading the game again, seeing how ithe engines run, tweaking more, etc.
