well heres the story, so on saturday, i was doing a tune up on my truck, so it would have a better chance of passing smog, its an 82' 150 by the way with a 302, at. so changed the oil changed the plugs, changed the air filter and the emmsions crankcase filter thing in the air pan. also replaced the fuel filter. so after all that i put the belt back on my smog pump. started her up and then the problem started, she'll start up but if i dont keep it at a high idle she dies. but keep in mind i thought it might be starving for fuel but i changed the fuel filter and when i had it runing my dad sprayed a good amount of carb cleaner in there to possiably clear and bloackages. before all of this happend i never had any problems with her before she always ran like a champ. so on to my next idea for a problem. i checked all my plug wires for a good connection and made sure i didnt cross any wires. checked the lenghts of them looking for wire burn from touching the manifolds. found one, didnt look that bad ut i changed the wire out. now she still wont go. so i think it might be faulty plugs but im not sure. just wanted to check for some input for others. any help would be grealty appreiciated cause shes the only thing i have to drive. thanks agian.

-jared

 

I have seen plugs that were bad right out of the box. It sounds like a weak spark, but you could have also dislodged something in the fuel line and it's clogging the carb.

Also it could be totaly unrelated.

You can try a power balance test. Get the truck running and then pull the plug wires one by one. Use a pair of pliers and ground them to the engine. This way if the spark jumps it goes down the ground wire and not to you. Listen and on the good cylinders you will hear a noticable change. On any that are misfiring the change will be less or not at all.

BE CAREFUL. There is the fan spinning and you can get zapped if the plyers arn't grounded. Also make sure you grab the rubber end and are not touching the metal.

 

Could be a vacumn leak, you may have bumped something while you were working and cracked or disconnected a vacumn line. Spray some carb cleaner around the base of the carb and on the vacumn line connections. Also feel the hoses to make sure they haven't hardened which makes them crack much easier.

 

yeah im still kindaof doubting the lack of fuel thing though. cause its running but when it goes and if i adjust the idler screw so that i can keep it going , then engine makes a big loping sound. im guna put in the old plus today cause i know those were good before i changed em out for the old ones an see what happens.

 

ok im still having trouble. i went and put in another whole new set of plugs, still nothing, it is running though, just lobing reallly badly. also put in a new set of plug wires. didnt help ethier. any one have any ideas i really need to get her running, any one think it might be the cap and rotor or even the coil. i dunno? please any advice would be greatly apprieciated asap. thanks

jared

 

i had a similar problem to this with my 82 f150 .. i did a full tune up on it it ran good for a bit and went downhill real quick .. after tinkering with it for a long while i wound up having to replace the timing chain but thats a long story... what i would recomend is to check you timing expecially if the engine dosnt seem to run right when it does run its possible that you spun your distributor a lil while you were doing your tuneup .. if i remember right timing on it should be 8 degrees btdc? check this before you set it there but this is what i would recommend to check

 

Did you change the PCV valve? Check the big vacuum hose that runs from the PCV valve to the carburetor. Sounds like you may have pulled it loose. It creates a big enough vacuum leak to keep the engine from idling. (Been there, done that.)

 

I agree with sycostang. to me it sounds too much like a vacuum leak. Check the lines coming from the booster, also check around the back of the carb to make sure the seal is still tight. If that's still not it look around the manifold for loose connections to and from it. Check around the smog pump and EGR and all that wonderful stuff. If still nothing is found, then check you dist cap to make sure your wires aren't crossed. Also make sure the rotor didn't burn up or the points are still good on the cap. And I believe that it is 10 degrees advanced crash, I think.

 

il have to check that out. but the only thing is on the timing adjustment. the truck has a duraspark ignition system and the distributer is bolted in like theres a notch where a bolt goes in and holds her down so you can turn the distributer to adjust the timing. so there im puzzled. but ill defanitly be checking out all my vacum lines and ill probably just throw in a new pcv valve while im at it.

 

PCV valves are cheap and it wouldn't hurt anything to change it. But what I was alluding to was that the big vacuum hose that draws from the PCV valve may be split, broken, or unplugged at the other end. Generally speaking, if the PCV valve rattles when you shake it, it's okay. When you pull the hose off of it with the engine running the engine will stumble or even stall unless you quickly plug it. You should have strong vacuum on this hose. If you don't, you may have found your problem.

 

Another thing to check is your EGR valve. If it is stuck open the engine won't idle well. Draw vacuum on the actuator. It should hold vacuum. You should be able to see it stroking as you release and apply vacuum. There shouldn't be a vacuum signal to the EGR at idle. It should get a ported signal and not unless the engine is at operating temperature. If it's getting vacuum at idle it's hooked to the wrong port.

On edit: I may have added that too fast. The EGR valve may work opposite of what I just described and vacuum holds it closed. I'll verify and post a correction if someone doesn't beat me to it.