Hey all,
I have a 1984 F150 with a 302 and C6. It usually runs fine but yesterday when I was pulling into the parking lot I was going a very low speed and was turning into a parking spot. I held the brake a little bit and popped the gas pedal to try and make it turn a bit sharper. Incredibly stupid I know. As soon as I did that it became very sluggish. Then when I went to start it back up it wont unless you put the pedal down a bit and rev it high right when you start it. After that it idles very weak and shuts off after about 15 seconds. I cant put it in gear without it shutting off either unless it is revved pretty high and then it hardly moves at all. It did this exact thing last year during summer. I didnt do anything to cause it then. It just was like that when I went to start it one day. It sat for a few days and I would check to see if anything had changed and one day it just started back up fine. I got lucky then because it just started back up and I coudlnt figure it out. Now I need to fix it soon because I live off campus and have to drive to class and work. I thought it might be a vacuum line busted off somewhere or the fuel filter clogged up. Any ideas would be greatly appreciated. Also in park it runs fine at a higher rpm. not sure what because there is no tach. Thanks

 

I can't think if much off-hand that would cause those symptoms and be self-healing. About the only thing I can think of - and it's a long shot - would be something in the fuel tank that is plugging the pickup, or maybe a collapsed piece of rubber fuel line? I'd check the fuel pressure maybe...

 

The fuel filter is the first thing that came to my mind too; since they're plenty cheap I would swap it out just to eliminate the possibility.

 

so it isnt the fuel filter. I can get the truck in gear and going but it takes a really long time to get up to speed. The engine sounds fine and I can't hear it missing or anything. My brakes seem a little bit sluggish too. Do you think there is a possibility I blew out the Diaphragm on my booster or maybe more likely a vacuum line on my tranny. I cant look right now because it has started raining cats and dogs again. Lovely florida weather is bright one second and hurricane the next.

 

It could be a vacuum leak - with the engine idling, take a spray can of carb cleaner and spray around common leak areas and listen for the idle to go up. If the idle goes up, that's your leak. Common places are intake manifold gaskets, carb base, or the brake booster.

 

Are your motor/tranny mounts in good shape? Sound to me like it tugged something loose or broke something due to the motor possibly moving/torqueing too much. That'd be my guess!

I had a 66 F250 Camper Special with a 390 many moons ago that would crack the distributor cap on the firewall if I torqued the motor too much.

 

are your brakes dragging? Check the temp of your rims.

 

almost sounds like a timing chain jumped a tooth to me. that would account for the weak brake boost and sluggish performance as well as the other symptoms. a simple vacuum gauge test can check this (low vacuum reading)
jim

 

so I found that my vaccuum advance line was cracked. Fixed it and now the truck will sit and idle fine in park and in gear. Now the only problem is that it wont get up and go. Its still very sluggish. Do you think it might still be the timing chain. My dad had mentioned that and I'm really hoping thats not it. Do you think now I might just be missing a line somewhere. My brakes are also back to normal or close to it.