Cranks but won't turn over
Hey there, first post here on the forum. I recently switched off my VTX 1300 and got a clean VRSCB 05 V-ROD with only 7k miles on it. Unfortunately the previous owner I got it from left it sitting with gas in his garage. After about 30 miles or so it turned off on me. I was able to bring it over to a Harley dealer in which they told me the fuel pump was the issue, and as the 05 VROD parts were discontinued they tried to get to buy the newer model which would also require a full fuel module & conversion for the total price of $1200 in parts. As a sensible person and college student with low funds, I declined and found an aftermarket fuel pump online. Gave my fuel module a cleaning and installed the new pump. It worked perfectly fine for about a day, I'd say around 40 miles in it died on me again. Basically the motorcycle cranks, but does not start. I'm not that mechanically inclined but my uncle who is a car mechanic gave me a hand in checking some areas. The battery was a bit drained so I charged it up and still nothing was resolved. We removed the fuel module to check if the fuel pump is working, and it is. My uncle used one of his tools to check electric continuity through the wires under the seat, seemed all good. Finally we poured a bit of gasoline down the butterflies (throttle body - not really sure what the actual name is) and it appears that it starts for a couple seconds.
Any ideas on what I should check next? spark plugs? fuel injectors? I'm all ears.