Yeah, I would hook up the other ends back up for now to keep track of them.

 

Be advised, that's a 1989 Vacuum Diagram.......

 

Should be the same. 4.9 with MAP. I could be wrong though.

 

I don't mean to repeat myself, but don't forget the 2 vacuum line going over to the top of the throttle body, those are usually connected to the Fuel Tank Vent Canister.
They don't have as much effect as the others, but remove the hoses and cap them as well.

 

Could be, I don't know. Here is a 96'. But like someone said, he should have a diagram under the hood somewhere. On the Air Box maybe.....

 

[QUOTE=vjsimone;17019643]I don't mean to repeat myself, but don't forget the 2 vacuum line going over to the top of the throttle body, those are usually connected to the Fuel Tank Vent Canister.

Mine are connected to the canister purge solenoid. Same thing?

 

The '89 and '96 lines look to go to the same things. The '96 is color coded and easier to read. It appears he is missing the line to the side port of the air pump.

 

Is the air pump the same as the smog pump? I have a vac sticker. To me it looks like one line comes out of the AIR D Solenoid which is where one of the missing lines is and goes to the Air Pump and the other goes to VRESSER. Is this correct? Thanks Sandy

 

[QUOTE=sandymane;17019687]Either way, disconnect those 2 vacuum lines from the Throttle Body and Cap for this test.

 

Today I disconnected the battery for 15 min as suggested. I capped the three vacuum ports on the tree. One was already capped (as it should be) firewall side of the V connection of the tree, The other two are capped with the FPR and the MAP being hooked up this time. The TB ports are plugged also. Nothing else is capped off. The idle was reduced maybe 50 RPMs. Top of tach needle just touching the 1K line.

Regarding the missing vac line pictured in post 45 above, if it is supposed to connect to the AIR/SMOG pump, I see no connection port on it. It only has the two large hoses attached. The Smog pump has been replaced because of a bad bearing.

Other than the one missing (if it is supposed to be used) line on the TAB or TAD (closest to the firewall) I am ready to do whatever comes next. RLA mentioned I should have replaced the Intake gasket when I did the Injectors. The gasket only had several hundred miles on it, but I will never reuse it again. Also, I have reused the TB gasket (about 500 miles on it max) but it looks good. I have not done a compression test and have not replaced the Oxygen sensors (no codes). That is about all I can think of now. Thanks Sandy

 

Did you verify there are no vacuum leaks in the MAP circuit and FPR circuits? You can test these with your vacuum pump, just to be sure. We are trying to eliminate all potential culprits.

Sounds like you left the PCV and brake booster lines hooked up? If so, add these to the procedure and retest.

The missing line will not go to the AIR pump. It will go to an AIR Diverter Valve or AIR Bypass Valve, which the plumbing from the AIR pump will lead you to. I believe on a 4.9 the valves may be combined in one unit.

 

I did not do the PCV but did block the brake booster. I will check the pcv now. Thanks R&R. Sandy

 

I capped the PCV which I had not done and the idle dropped about 50 more RPM's. There is now a slight gap between the tach needle and the 1K mark. Still rough. Sandy

 

Congratulations, you have eliminated the accessory vacuum systems as the major source of the un-metered air assuming you are confident in your work.

You can now worry about other culprits such as worn throttle body, leaking gaskets, cracked intake manifold, (the vacuum tree and the PCV fittings themselves are potential culprits too), or internal engine wear.

 

I have smoke tested the truck three times with a professional smoke machine and done the accessory test. What would you suggest to check internal engine wear? Compression test which hasn't been done? OR??? And remember nothing changes when I disconnect the IAC when the truck is running.