My truck won't start its turning over. it's a fullsize 94 blazer k15

Could be many things but to narrow it down try this to start.

You need three things to get going. Fuel, Ignition, Air.

Check all fuses and relays first.

Spark check , remove a spark plug and carefully hold it (long handle pliers) close the the engine block while someone turns the key to start. You should see a good strong blue spark. No spark you have an ignition issue.

Fuel check, crack open a fuel line just enough to leak, close to the filter or an injector. Crank the engine and you should see a fuel leak. No leak you have a fuel problem. Usually a clogged filter or fuel pump. If fuel leaks on the supply side to the filter then the filter is clogged. Turn the key and listen for the fuel pump electric motor (gas tank). No sound probably the pump.

Air. only a badly dirty filter will cause this kind of problem. Remover and check. Could even remove and try turning the engine over.

Some direction to get you started solving your problem

Please rate if it helps.

Check for spark at plug 'if no spark you or someone must do a spark check if spark present check fuel pressure if no pressue carefully spray a small amount of starting fuild in intake ''' remember Small amount if starts then promlbe is in fuel system , pump, or even, computer