PAF engineers are being educated and trained at PAF Academy Risalpur, College of Aeronautical Engineering (affiliated with NUST). The college offers undergraduate programs in Aerospace and Avionics Engineering. Young engineers achieving GPA 3.0 or more are being sent for post graduation qualifications including MS leading to PhD from various top foreign universities abroad.Pakistani "engineers" can't just "tweak" an off the shelf product. If it was an easy fix it would've been done by the manufacturer long before.
And PAF has mechanics working for them not engineers just FYI.
Similarly PAF aero technicians are being graduated from School of Aeronautics (SoA) and School of Electronics (SoE) Karachi.
Young engineers and technicians undergo a very comprehensive training program during their career progression.
Moreover, PAF engineers are not only confined to Aircraft or related equipment maintenance and manufacturing process management but also carrying out research and development at various centers. In addition to these assignments, engineers holding MS and PhD qualifications are also tasked to teach undergraduate courses in CAE.
So, please do not underestimate PAF aeronautical engineers and aero technicians. Both are adequately educated, skilled and experienced in their fields.
Hence, possibility of tweaking old RD-93 fuel system at PAC cannot be ruled out. Also appreciate, that JF-17 users are the sole customers of RD-93 engine. Till now about 150 to 200 RD-93 engines are being held with JF-17 users. Hence, this quantity will not "motivate" the manufacturer to "tweak" older RD-93 engine free of cost.
Upgradation of RD-93 to RD-93MA was done under contract between Chinese and Russian manufacturer.