SiR-EJ1

so i have hondata s100 in and the cel is on and when i check it it stays solid. well as i am driving the cel will turn off and if i turn the key back one click for a couple seconds then turn it back on the cel returns and everything is fine but every now and then it wont come back and i loose all fuel pressure. i try and start it and the fuel pump doesnt prime. but after awhile on a random turn over the fuel pressure will jump and it starts. could this be the main relay or something else?