It probably ain't the main relay. 9 chances out of 10 it is a back magnetic pick-up in the distributor. My neighbor has a prelude that did the exact same thing. and after I tested the coil and found out it was not firing I checked the magnetic pick-up and it was bad. He then replaced the distributor and it fired right up. The reason it will cause the symptoms you are having is because it registers a rpm signal from the distributor. If the pick-up is not working then it is not registering a rpm signal, therefore it will not run the fuel pump or fire spark or injectors. If you need some more help just holla at me and I will help you the best I can.