89 f150 302 A0D 2WD

ok, so in an attempt to diagnose my high idle.....i may have found the vacuum leak source.

while pulling vac lines from the source (the intake mani) and plugging them while the motor was running i was hoping for some changes in idle. i also had a vac pump and gauge so i can test individual vac lines and entire assemblies if they leaked vacuum.

weird part: i unhooked the line at the manifold that t's off to feed the cruise and this metal can located under the front headlight. the motor started to die so i tried holding my thumb to seal up nipple at the intake mani, but the motor died anyway.

i then checked each line in this assembly; the lines and the cruise control holds vacuum, but the metal can does not. the line that feeds the can is good.

what is this metal can? and why does the motor die when this is unplugged?

PROBLEM: even when i hooked up that line back to the vac source the motor has a really hard time starting. AND staying running. why is this?

i was told it might be a vacuum regulator regulating the vac system just like the FPR does for fuel. assuming this is correct then that means the vacuum changes at the FPR (since this runs on vac) flooding the motor and it dies.

anyone?

 

possible this is a vacuum reserve can
it keeps the a/c and other vacuum using items
working when you go full throttle and have
low engine vacuum
when you open the throttle hard does your a/c blow thru the defroster, if so then the can is not holding enough
vacuum to keep the blend door closed

 

right now i'm not worried about the HVAC. i just want the thing running and not idling sky high.

how does unplugging this vac line from the intake stall out the motor? and how does it make starting it harder after it's plugged back in?

maybe i should just find a good used one at the yards and replace it and see.

 

It is the Vacuum Reservoir for the EGR and AIR controls and nothing to do with A/C or Heating controls, they have there own and theirs it is a round ball.

This one is the one that is in the vacuum diagram under the hood.

The HVAC is not on the diagram.

 

so replaced the vacuum resevoir. it was rusted pretty bad that it pretty much crumbled to peices. got lucky and found some in the junk yards. got luckier as out of all the ones i found at the yards only 1 was still good; as all others were alot worse than my original can. tested it at the yards with my vacuum pump and it held vacuum!

popped it into the truck and hooked up a vac pump and vacuumed out the can and the speed control (cruise control) before the check valves. hooked the the main line back to the vac source (vac manifold on the intake manifold) started it up and it warmed up but still idled high.

there is a solenoid bolted just below and in front of the ignition coil that has 2 vac lines going to it. one line is hooked up to the vac source and the other runs off to somewhere i forgot. i tested this assembly and it's not holding vac. what is this solenoid? and is it supposed to hold vac?

 

either the egr valve is not opening because of carbon or the egr vacuum control on the firewall is the problem. unplug the vac line on the egr when you crank the truck and see if it changes the idle and makes it better kenny