Hello, this is my first post, I am new to this group. I have an 86 F150 long bed, 4x4 with a 302 4 speed. I recently got this pickup, my dad replaced the high pressure fuel pump, and the pumps in the tanks have been replaced as well. This evening while driving it I was going along smoothly at 65 mph, all of a sudden it would surge down to around 45 mph. I pumped the gas a few times, pressed it to the floor and nothing would happen. After a little bit it would go back to normal up to 65 and driving fine. It did that a few times. The last time it did it, it went down to around 35 mph and lasted longer before it went back to normal. I was close to home then so it didn't happen again. What could be causing this? Thanks in advance

 

Welcome to FTE

I dunno, but somebody here does. They'll get ya all fixed up here directly.

 

Thank you, my dad showed me this sight.
Does anyone have an idea on what it could be?

 

It being a 1986 with a 302, it's computer-controlled... so ask the computer what it thinks is happening... IOW pull the codes, here is one explanation on how to do it:

Ford Ranger - Testing EEC-IV Equipped Engines

 

Welcome to the forum, Luckylady11!

ctubutis has given sage advise, as usual, but another option, if the truck can be driven, is to take it to a nearby auto parts store. Most have the ability to scan the computer with a hand held scanner. Normally, there is no charge as they hope you will buy parts while there.

 

Thank you, we are going to do that this weekend and hopefully get it figured out

 

I bet on the Evap canister purge valve.

 

Let us know what's going on.