Vacuum System help.

[paylov]

Hey Everyone,

A few months back I purchased a 1994 K1500 5.7L TBI. It drives fairly good, and didn't notice anything wrong when I test drove it. However there are a few issues, which i believe have to do with the fuel and air mixture. on the first crank of the morning it has a rough idle for about 30 seconds and then it settles out and is all good, and it will also stall when coming to a stop and certain rpms (but randomly and only a few times a month). i bought it knowing it would need some work, and it and recently had an engine rebuild. but after noticing these problems, and being the way I am and wanting it fixed, I started digging.

I have found a few lose connectors in the engine compartment, and after my rabbit hole of online searching i found 1 of those to go to the MAPS sensor, which is missing. and after digging into that i noticed some more things missing. So in short, I discovered basically the entire vacuum system coming off the throttle body is missing. all of the ports are plugged (so no vacuum leaks) except for the PCV valve, which is there. BUT, i am missing the MAPS sensor, EGR Solenoid, vapor cannister vent valve, and the vapor cannister purge valve, and all of the hoses. I believe this to be a big part of the idle and stalling issues, as i also have a check engine light for low MAPS sensor voltage ( since it is missing).

The diagram under the hood has helped me a little, however I am getting stuck on how the vapor canister parts connect.

if anyone with the same setup could possible give some god pics of how all of the vacuum hoses and sensors are connected, and possible lead me in the correct direction for some good vacuum hose, it would be greatly appreciated. i just would like to make sure I am not missing any sensors before I order them.

Thanks

 

[jigsaw]

On the canister side one side goes to the fuel tank the other to the sensor then to the tbi. I dont know at what year they stopped installing air pumps but my 95 doesnt have one n dont think 94 had one either

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[jigsaw]

Ok this is the sensor i was talking about it goes between the canister n the tbi i supose its some sort of pressure switch like a purge valve to let vapors in. U see the hard line it goes to the canister

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[paylov]

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Thanks man, heres the diagram under my hood. Im not going to bother with the fuel tank pressure valve, but im going to add the other 3 back. Thanks for the pics. The only sad thing is i dont have the brackets for the seonsors and you cant buy them, so i guess ill jist rig it until i can get to a pick and pull

 

[someotherguy]

Yeah MAP sensor being missing is the biggest issue here. The PCM needs it in order for the engine to run correctly. I would fix this ASAP then change your oil. The engine most likely has been running very rich due to no MAP data.

EGR solenoid is important too but down the list for sure. You may not currently have a code 32 because the engine likely isn't getting to the stage where it would run a test on the EGR.

The plastic lines the factory used to hook everything up may not be available or easily found (at this point most of the old ones are brittle) - but you can use vacuum hose instead, just be sure to get good hose rated for the purpose (fuel/vapor) because the plain rubber windshield washer style hose will deteriorate quickly. Route it so it can't kink and get restricted.

Richard