Ok, so we have 3 engines already mentioned, one of which doesn't exist. Please tell us exactly which engine you have...
If you have an earlier 4 cylinder, it's either 80hp or 85hp (though a bit later it was called 75hp). Or if it's the smaller block 4 cylinder it could be a 40, 45 or 50hp...
If it's 1993, then as a 90hp it will be a 3 cylinder.
If it's earlier (pre 1986) as a 90hp it will be a 6 cylinder...
There never was a 4 cylinder 90hp... Unless it's white, in which case it will be a V4... :facepalm:
Chris....