05 suzuki gs500 f starts only with choke on but will not stay on for longer than 15 seconds. when i give it any throttle it dies

OK, What EXACTLY is it doing when you try to start it? This can give clues as to where the problem might be. Does it do nothing at all? Does it crank very slowly? Does it just spin over quickly and not even try to start? Does it crank over, try then stall out?
2 chokes? Have a closer look at these. Twist the throttle grip as you do. Does one of the chokes move as you twist? The second 'choke' might actually be the linkage for the throttle cable.
Comment below with more information and I'll try to help you more.

Hello, bike not running off of choke is an indication that the pilot circuit in the carbs is plugged.. the choke is a enriching circuit hence why it runs only with the choke on. When turned off the bike starves for fuel and dies. My guess is the bike has sat for longer than 4 months and the pilot jets are plugged from varnish... they will need to be removed and properly cleaned.

1. Fuel cap or fuel tank is not venting properly.
2. Fuel filter clogged.
3. Fuel line pinched or kinked.
4. Float needle and seat sticking.

To test fuel flow, have a 2nd person stand over air filter (air filter housing open) with a can of starting fluid in one hand. Don't give any throttle, then 2nd person gives 1-second squirt into air filter while you're turning starter motor (no throttle). When engine catches, immediately give one third to one half throttle. Just before it dies, 2nd person should give another short squirt of starting fluid to keep engine from dying. If throttle won't keep engine running and only starting fluid keeps it running, then yes, no fuel is going through fuel lines. Either its a fuel pump issue or maybe there's restriction because of clogged dirty fuel filter. If it starts but runs rough and has black exhaust smoke, then its clogged or dirty fuel injectors.

pull the vacum line off your fuel pressure regulator. If it smells gasy or has gas dripping from it, replace the regulator.

If you have good fat spark and there was no undue valve train noise prior to this problem, then your problem lies with fuel delivery, or restriction of it.

Air/fuel mix has to be right at start up and as such, all of the inlet system should be inspected or serviced. From air filter inlet, filter, manifolds. Fuel tap, fuel filter, fuel lines, float levels, float needle and seat, pilot and main jets, needle and slide.

Start with filters, check needle/slide are rising in unison and fuel is flowing freely to floatbowls. Good idea to take drains out of carby's and spray some aerosol carby cleaner down fuel lines till it flushes thru' carby' drains. Check carefully condition of inlet manifold providing an airtight seal. There is a sitelink below that has exploded views and part names for all sections for your bike to assist.
Cheers.

http://www.cmsnl.com/suzuki-gs500-2000-euy_model13470/partslist/

check crankshaft seals,maybe sucking air. most of the time the seal on the starter side. hope this helps.