So I went to do a tune up on my truck yesterday and found a few disconnected vacuum lines by the distributor, the one goes into the back of the intake, one comes from the drivers side from the cruise control, then theres a hard plastic line with a rubber boot on the end that comes up by the fire wall, and then theres this weird shaped thing(in pics) that seems to have a line that suppose to go to it. i tried figuring it all out by the vacuum diagrams in the chiltons manual but i just got confused. i tried to call the guy who last worked on it who had to put lifters in but i couldnt get ahold of him. so please any help would be useful.

 

well i finally figured out the mess but i have a problem, everytime i connect the line that goes to the nipple on the back of the intake, after running and while idling in gear at a traffic light or anything like that it acts like its going to die and then surges to keep it self running, any suggestions?

 

That thing on your line there is a check valve - make sure it's facing the correct way, or else engine vacuum won't reach the things that rely on vacuum to work - namely the heat & A/C system temp. and vent controls.

As for your running problem, that could be an air leak that was masked by the lines being disconnected before. Hard to say over the net - could be a few things. IAC sticking or gummed up, timing off, or just too low an idle setting - can't remember if the TBI units had an adjustment or not - I know the older Fords did ...

 

the picture i went off of that i found off the internet has the, what you call the check valve in the rubber boot on the hard plastic line that comes up behind the engine. is that wrong?

hmm.. idk if the idle can be adjusted or not, i have the CPI motor. ill look into the other things ASAP though. thanks man

 

I can't tell if it's right or not over the net - you;d have to remove it and blow through it to see which way air flows through, then point the air flow toward the engine (intake).

Basically the vacuum just goes from the intake, then T's off - one side goes to the transfer case vac switch on 4x4 models, and the other goes to the vacuum orb (round plastic ball that stores vacuum). Another probably T's off of that to go inside the cab for the heater controls, and you might have another going to cruise control.

 

would a pic help? i can get under the hood tomorrow snap a couple pics. i just want this stuff fixed

 

I can't tell by looking at it - you need to remove it, and blow/suck thru it to see which way air flows through, then orient it so that airflow moves towards the intake. If it passes air both ways, then it's junk. All that valve does is keep vacuum in the system when the vehicle is shut off, so it's not really critical. The rest of the lines just go where I explained.

Main thing is, there can't be any air leaks. If there is, it'll run like crap. Most of the time you'll hear the leaky line hissing at idle - that should point you in the right direction.

 

alright thanks man, itll be finely decent out to be able to spend sometime out there looking at it. if i cant figure it out, im taking it to my buddys dad shop because im sick of it lol

 

The large end of the check valve goes to the intake manifold, (vacuum source). The cone shape end goes to the HVAC, vacuum reservoir, and 4WD if equipped, (cruise is all electric, no vacuum).

 

cruise on my truck, a 92, uses vacuum. theres a hose that runs from the drivers side into this cluster of lines.