22re starts then dies in a few seconds

i'm trying to put someones project back together.it starts right up but then dies.(it's a rock crawler)it has an external fuel cell,i replaced the fuel pump and filter.checked the fuel dampener.i also realized there is no charcoal canister.could that be it?it has a green sticker so smog is not an issue.a few people mentioned possibly the cold start relay?or afm. any and all help will be greatly appreciated. THANK YOU