Gentlemen,

I appreciate your help and knowledge on this forum. My 78 F150 (351m) runs great, no problem with anything. However, sometimes when I'm going slow - just above idle speed up a small grade it will buck a couple of times. Never on a highway, at fast speeds or anything else. Just on an upgrade at slow speeds (like in a parking lot). Anybody dealt with anything like this before? Thanks!

 

Pull your distributor cap and check for excessive play, or easy spin by trying to turn your rotor by hand. I had a distributor roll pin shear, and what you are describing was the first thing i noticed when this happened to me. The pin sheared, the rotor turned, causing the timing to become incredibly off, and the truck didnt have enough power to **** a foot. Once i got moving, it was fine though. If this is the problem, let us know, and i can tell you how to fix it. Fixing it takes about 20 minutes, a very narrow punch/push pin, a hacksaw, file, small hammer,and a 12 cent roll pin from any car part store. Keep us updated.BTW, i assume you know this, but have the truck off when you pull the cap


---JOHN

 

could be EGR related.

 

I have the same problem. To get to my hunting camp, I run 4wd low range 2nd gear, up a steep incline. It is a very rough ride. My79 f-250 will start to buck severely. I thought it was the fuel level in carb, or my foot bouncing off the gas pedal. I'm pretty sure it's neither. Would someone please explain how to check and replace the roll pin in the distributor. Thanks for any help.

 

check your timing