I'm new to the forum and just purchased my second Ford pick-up, a 1986 F150 flareside manual (been driving a 2000 ranger 4 cylinder 5 speed for years). I've been looking through the forums trying to track down similar issues but haven't had a ton of luck. The fuel tank doesn't fill properly (vent tube is not set up right, recent previous owner installed a new tank and the filler tube is merely clamped on black hose) but it also idles high after running for a brief period and is low on power after running for more than an hour. When it's acting like this it sounds like it misses too. I'm guessing fuel filter or catalytic converter issues but it's difficult to guess with the varying amount of work the previous two owners have done.

Any help is appreciated before I try diving in semi blind. I can post pictures if needed, I'm currently in the garage freezing my a** off finishing the clutch on my ranger.

Thanks

 

What engine? A 1986 6-banger or 302 V8 will be computer-controlled, ask the computer how it feels about things:

Ford Fuel Injection » How To Run a Self-Test

 

The carborateured inline 6 is what it's got.

 

It's a computer-controlled feedback carburetor; pull the codes and see what the computer says.

 

You are going to the junkyard and get the proper fill hose assembly for the tank correct? That's what I would do.