i was going through my truck again tonight and i found a pretty heavy duty vacuum line that is about a foot and a half long that basically goes out the front of the throttle body area and then is teed off. I have a haynes manual but i can't seem to decipher what this vacuum line is for. It is an 88 dodge d-150 with a 318. Thanks for your help.

 

also, my vapor canister seems a bit fishy. There outlet on it that has a plastic cap put on it. I don't know if this is suppose to be hooked up or not. And a few weeks ago i completely cleaned out my throttle body and it looked like it was full of coffee grounds and such, which prevented any vacuum getting to my fuel pressure regulator. i have since cleaned that all out, but now i'm running into problems again. Any suggestions? Is there a way to test the fuel pressure regulator with a vacuum gauge or anything? it does hold vacuum, but i don't know of any other tests. I read another post that had mentioned their canister ruptured and filled everything with tiny charcoal pellets. Is this a possibilty. I keep setting off a code 52 stating the engine runs rich. I have replaced the o2 sensor, it ran okay for a little while then bam, its reading rich again. The plugs were all black so i replaced them yet again. i'm open for ideas.

 

a friend of mine has an 85'ish Ram 150 with a 318 and 2bbl carb. on one of our camping trips it developed a vac leak and wouldn't run at normal 1/2 throttle. it would only run at either idle or wide-open. i used golf tees or rubber plugs to plug up all his vac lines as close to the carb as possible, which temporarily fixed it. we then connected them back up one at a time until we found the culprit. it was some useless smog control that didn't work anymore. we plugged off everything non-essential and went on. we left the evap cannister connected (which was a mistake).


a few years later he was driving along and it started running crappy and then shut off. he had to have it towed home. it would start, but not idle, and not rev up. we dropped the exhaust and found the cat to be clogged. so then it would rev, but not idle. pulled the top off the carb and it was slap full of charcoal pellets from a ruptured evap cannister. we did a carb rebuild and left the evap cannister off. had to have cat replaced. i guess a lot of the charcoal went through the motor and that's what screwed the cat. the stuff that stayed in the carb screwed the little idle circuits.

if your cannister ruptured, you've probably got a bad vac leak through it.

 

There should be 5 vaccum lines comming out of the throttle body. One routes back to the throttle body on the side. One goes to the check valve and canister. ONe goes to heated air diaphragm, one to a tee and to PCV and to canister line. And the one you talk about justgoes toa dead end. This is what the vaccum diagram in the Hanes manual i have says.

 

I am also running super rich and i just can't for the life of me figure out what the heck is causing it. When i reset the computer it takes a while and it runs better but sure enough eventually it will show that its running rich and i think it enters that limp in mode and will stay running rich until the computer is reset again. I just can't believe the problems i'm having. i have several posts on this and anymore help or suggestions would be great. i should have a post that goes through everything i've changed on this truck, which is practically every vacuum line, emission sensor, etc. thanks.