Sir,
IR does not need to increase fare on these petty increase issues. IR has already raised the fares extensively on account of
* Conversion a good number of Genral quota into Tatkal
* Heavy cancellation charge on Tatkal
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Higher cancellation charges
* Extra charges for taking reservation from a station other than journey origination
etc. etc.
And hence this Rs. 2 hike in Diesel cost is not going to trouble IR.

The hike will definitely affect the financial health of IR.
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As per a news report on CNBC yesterday apart from fuel hike govt has imposed a Service tax on specified goods transported by Railways.
An amount of 426 crores will have to be paidby railways for current financial year payable next year.
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15% of IR expenses is on account of purchase of fuel from Oil companies.
Add to this it's idea of running diesel locomotives even in electrified routes
for example
Udyan exp (Mum-SBC) runs on WDP4 right from CST even though route till Pune is electrified.
Similar is the case with Hussainsagar exp, Hyd Express and many other south bound trains as well.

The diesel run in ur mentioned section, is just to cope operational issues!!!
The Loco change will increase halt @ Pune & the timing of these trains at one point (UP or DN) is highly conjested>>
Plus, to manage ldle Loco in Pune is too cumbersome.
So IR is managing this by mix set up of Loco combinations for different trains.
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Chennai Exp, KOP bound trains etc do have Electric Loco @ that time only>>

I know it is for operational issues due to lack of WCAM locos but IR is paying a heavy price for the slow progress of AC conversion work.
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Even at Pune all the trains do halt for atleast 15 mins without change of loco/staff. This time is sufficient for all technical purposes.
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imagine the effect if the recommendations of one of the committee appointed by IR a few years back is accepted in toto.
"Run Diesel under wire"