My 89 G20 cranks until battery is almost dead before starting and if I let it die out while cranking I don't have enough juice left for a second attempt. The battery and alternator are fine, I'm thinking it might be a weak fuel pump? After it starts it runs like a champ, well except for the very loose steering, but thats another post.

Thanks!

 

how are the plugs/plug wires/cap/rotor? air filter? fuel filter?

 

air and fuel filter have been replaced, plugs and wires still seem to be in good shape as well.

 

have you checked the timing? check fuel pressure if you can.