Point Me In The Right Direction

So guys I have a 1988 350d. While working around the house this summer it has developed a hard starting issue after running it. When it has a cold engine it hits as soon as I hit the starter button. After my initial run with the engine warmed up and turning it off the quad becomes impossible to start. If I let it sit overnight it will fire right up. Could a partially clogged fuel line be causing this?