Actually, Tejas development started in 1984, not 1985. Furthermore, you think Americans would let India export Tejas and compete with F-16? The US can block F404 engines sale to India.
It doesn't work that way. You see the US
government isn't the sole entity that stands to gain (or lose) from a sale (or
a lack of sales) of F-16, or any other fighter. Most of the technology & development/production work is done by
private companies & private shareholders.
Even if a certain country rejects F-16 and selects Tejas for purchase, US corporate entities like GE will
stand to gain a great deal of money, business and after-sales agreements by selling the engines to the
said country, to power their selection (Tejas).
An example is JAS-39 Gripen powered by American GE engines. Just look at the number of instances
Gripen & F-16 were pitted against one another in international tenders. Eventhough the Gripen NG pretty
much outmatches any available versions of F-16E/F, the US will continue to provide the engines for
this plane, and therefore stand to gain from a deal which they would otherwise get nothing out of.
Even in the MMRCA after both US fighters (F-16IN and F/A-18) were ejected, US was still willing to gain
something from the tender, they approached us offering to supply the weapons package for any
of any of the two downselected fighters at that time (Rafale and Eurofighter). Eventhough India isn't
interested in getting US weapon systems like missiles for the L-1 bidder Rafale, the Americans are
still ready to sell us AMRAAM, Sidewinder, Paveway etc. etc. anytime we ask.