It should close tightly unless it's broken. So, I'd suggest fixing and/or oiling it.
Last resort: just slam it.
on the right side of the pickup follow the positive cable.
on the right side in front
below the right side of carb.
4 and 6 cylinders wont change out.
look at the right side of the firewall.
right below your thermostat housing
right now ,theirs a1985 Nissan truck service manual on eBay for bid.
On the 1997 Nissan pickup its just above the oil filter, lower right of engine, access through right front wheelwell after removing wheel, it's a screw in affair.
It is located on the right side below the gas cap.
I own a 97 pickup with a ka24e and the vacuum diagram is right on the hood. But a local Nissan dealership should be able to print a copy of one from their service manual for you.
The right type of fluid will keep a car running at its best. The 1995 5-speed Nissan pickup uses 75W-90 Gear oil.
the computer should be under the dash to the right of the gas pedal