Fuel line schrader valve on an '86

there's 2 places it would be. the first and most common is on the hardline that connects to the fuel rail where you've already been told, behind the alternator, kinda by the front of the valve cover. more than likely it'll have a black cap on it, so if you've been looking for a bare schrader valve, that might be why you overlooked it. the second place i've seen one is on the plate the fpr bolts to. i've only seen a schrader valve at the second spot twice though, once being on my current car (fuel rail looks to be factory aside from that schrader valve. the fuel rail came with my cobra intake, my factory rails did NOT have a schrader valve in this location) and once on a random car at a shop.

My 86 Capri has one behind the alternator but it's low and hard to find....

my 86 gt has the valve literally about half an inch from the pressure reg. just find your pressure regulator it should be right next to it. probably has a little black cap on. it Its on the fuel rail passenger side very close to the firewall.