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I picked up the truck last Monday and have been going through it to get it registered.
1996 F150, 4.9 I6, 5-speed manual
I tried reading codes but my Actron wouldn't connect. Changed the fuse and voila - no codes. Went for emissions and failed due to no CEL at KOEO. Took the dash apart and replaced bulbs. When driving back to get emissions, the CEL lit up - P0171 confirmed and P0174 pending.
I've checked fuel pressure which is steady at 45 psi KOER. Good fuel pressure
Checked EGR valve with Mityvac and its functioning correctly. Now I'm on to checking vacuum lines. I did notice a few lines were not connected properly so I reconnected according to the diagram under hood. I'm stuck with the line pictured as to where it goes. Broken vacuum line
OK, I checked that line again and now the problem is that the other end of the blue circled line isn't connected to anything - its just a broken piece kind of dangling without being connected to anything. I checked around the area and can't see anywhere a line should be connected. What is that line supposed to be connected to?
just to make sure we on same page, the blue circle around black line goes to where the arrow is, and that is a check valve for vacuum, but your saying that line dont go anywhere? SO 2 questions do you still have all your smog stuff working? any way to back up and take broader pic, I'm assuming your on pass. side, with that aluminum insulation that covers the ac/heater box by exhaust manifold? does all your heat/ac controls work inside truck, on OBDI one black vacuum line goes inside truck for controls, if yours work, try plugging that broke piece on check valve and clear codes,
I went ahead and changed the air filter and cleaned the MAF sensor. I was able to take some extra pics -
This is just a wider view of the line in question
This is the piece that's just dangling.
As far as I can tell this is the only vacuum line not connected properly.
AC/heat does blow, not well though. A PO disconnected the heater hoses from the firewall connection and used a 90* fitting to connect the ends together. Any idea why that would be done?
I'm assuming the broken vacuum hose is coming from AIRD to the three-way connection before the vacuum reservoir since thats the only place I see a check valve? I'll update once I get the chance to look at it.
heater hose having a 90* in it, may mean heater core started leaking? If your smog stuff has been removed you can plug/tape/small screw in it, unless you live in a sniffer state and get checked every year, then you need a piece of 5/32" rubber hose to fix, you should be able to pull that small piece out of check valve, put a longer piece in and slip the 5/32" rubber hose over it and same thing on your AIRD
I've finally had some time to come back to this. I found this thread and traced all my lines https://www.ford-trucks.com/g/picture/8930076 but no one seems to follow the line I'm asking about. As far as I can tell it should go to the vacuum reservoir (according to diagram) but there isn't any port or fitting to place it. This is literally the only line that I have disconnected and I would love any help/feedback.
Wanted to add some more info - the line originates on the vacuum tree and goes to the check valve right before the 3-way split after which the 1st break happens. Then its the dangling piece I've already pictured. I need to know where the end of the broken piece goes because the diagram says it should go into the reservoir but those ports are already taken. Thanks
Last edited by 96Fe2O3; Jun 14, 2019 at 02:58 PM.
Reason: Added more info
One side of the check valve(white side)/tee goes to the HVAC vacuum reservoir, the other port of the tee goes to the HVAC selector **** on the dash via an access hole in the firewall. The vacuum supply line attaches to the black side of that check valve. You have a red vacuum line supplying vacuum, that was obviously repurposed. It's usually black. Color really makes no difference, just pointing out what the factory did it.
Where does the black vacuum line run to on the bottom of that tee?
I wanted to give a quick update - reconnecting the line in the last series of pictures did the trick. The CEL cleared and I was able to pass emissions. Thanks for the help, I wouldn't have been able to figure this out without this forum. Cheers.
.... A PO disconnected the heater hoses from the firewall connection and used a 90* fitting to connect the ends together. Any idea why that would be done?
Laziness? There is an access panel behind the glove box. Replacing the heater core is a 30 minute job.
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