Here is my problem. I have a 1992 GMC Sierra and doing a TPI swap. The engine is a new 98 vortec and the TPI system is from Affordable Fuel Injection that came with computer and all sensors. This system is has no EGR components of any kind so I am left with one concern that I am not sure of... the vapor canister. There are only two ports, one to the tank and one for vacuum that went to the original TB. I researched and found that older systems used a timed vacuum to the canister but I am unsure what to do because of this... the diagram of the proper vacuum routing for this system shows that there is supposed to be a 3/16 port on the side of the the throttle body for a timed vacuum source but there is not one because there is throttle position sensor on the side that is show where this vacuum port should be. There are two vacuum ports on the throttle body, one indicating the pcv valve and one for the other valve cover. The pcv valve goes to the one behind the throttle plate and the other is in front of the throttle plate. This is my question. Can I tie in to either of these for the vacumm canister and which one should I use, or should I not hook up the canister at all? I don't want to cause a negative pressure issue with the gas tank so I thought I would asked the experts before I mess up.
Country: United StatesMake: GMCModel: Sierra 1500Year: 1992Engine: 5.7 Vortec
Hello and good morning. Generally the charcoal canister is hooked to the throttle body via a canister purge solenoid. This is a computer controlled solenoid and does not allow charcoal vapors to move to the intake until the computer commands them to. Check with the manufacturer of the wiring harness and ask them if it has provisions for a canister purge solenoid. If it does, then it's easy, run those wires to a canister purge solenoid and place that solenoid in between with the vacuum line to the throttle body. With that in place, you can tie that line into manifold vacuum because it will not flow until the computer opens the solenoid.
Your JA Expert,
Thanks for the answer. I was looking at the solenoids as an answer but wasn't sure. I'll check my schematics today but I'm sure the ECM has provisions for this. Thank you for your time.
One last thing. I need to verify that you are referring to the EGR bleed valve solenoid. It is the only one with an in and out vacuum.
No it will be the Canister Purge Solenoid. This too, will have an in and an out for vacuum control. In this case it will block the flow of vapors from the canister to the intake manifold. The EGR solenoid is a different one, and controls the amount of vacuum supplied to the EGR valve.
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Hey Ivan. Sorry to bother you again, but I have a problem. I contacted my TPI guy and discovered that the EGR system in my ECM is disabled so my only other choice is the vacuum type canister control solenoid. There is an in and out vacuum and then one on top for I assume the vacuum for the control of the solenoid. What vacuum source would I use for this?
I believe you should connect the vacuum control to a ported vacuum source. Try that and see how things seem to work.
Hey Ivan. Thanks for the info. You advice is invaluable. I have tried to accept the answer twice so you could get some more money but there is something wrong with the site. I will see if I can deposit the amount as a bonus on the one it did accept and see if that will work. Thanks again.
Thank you very much. Let me know if you need any additional help as you proceed. Your finished product should be awesome.