Has anyone ever seen a diagram that shows a good view of a 3g81 (550cc) or carbed 3g83 (660cc)? I've done a fair share of searching and think it's time to beg for or create one. Minitruckcentral's diagrams are cool for identifying parts and Dan's manual is wicked choice but I'm starting to think there's nothing in there like what I'm looking for. The carb tuning techniques thread is some help though because it tells me what the 4 on the bore of the carb do at least. I need a picture showing me what each nipple is and where it connects to. I'll just go down there and tell you what I have.. then maybe we can fill in the blanks for everyone, but me first Here we go. Version 1.0 (I will update this photo until it's right!) Uploaded with ImageShack.us
#8 goes to #2. Mine has a red check (PCV?) valve inline with the hose. I'm looking at the "carb tuning techniques" thread and I see that 14,15,16,17 are probably Distrib, EGR, Canister, Vacuum switch... but I don't know which is which. Can anyone throw me a bone? BTW it got dark before I could finish the stuff on the filterbox and air pipe between box and carb.
#12 fuel inlet (from gas tank) #13 fuel return (to gas tank) #11 might be idle up actuator (not sure where it's supposed to connect)
I will dig into my 94 Minicab repair manual and parts catalog for the info you need, or look directly at my 3G81 Minicab to try to find some answers for you. It may take a couple of days, though. Busy at work, not a lot of time at home for doing research. Long work hours + long drive = not a lot of time to spare.
I'm almost done. Did a little guessing and found a home for almost everything... Will update the drawing later tonight. Now i will search for fluid types for me engine on forum and maybe spark it up tonight.
3g82 vacuum diagram SOHC carb. #1 (Positive crankcase valve) connects to #7 Sucks oil vapor from valve cover back into intake manifold. #2 from valve cover to #20 canister. #3 (vacuum ignition advance). I guessed and used #12 #4 coolant temp air nipple? plugged. #5 Unknown. Plugged. Has full manifold vacuum though. #6 Brake booster vacuum. #7 Connects to #1 #8 I think this is EGR (exhaust gas recirculation). needs vacuum but I have no idea what number. I guessed and chose #11 #9 have no idea what it's for. plugged. #10 Had big vacuum at idle and looses vac sharply when throttle opened. (For the mysterious vacuum switch I think). #11 has some vacuum when throttle opened. I guessed and hooked #8 EGR there. #12 guess hooked to #3 distributer vacuum advance. #13 guess hooked to canister #21 #14 a diaphram connected to throttle shaft. Idle up? #15 fuel supply #16 fuel return #17 #18 hooked to #2 #19 Canister I think #20 to valve cover #2 #21 guess hooked to #13 My fresh rebuilt engine runs like a POS so this might end up being the "how not to plumb your engine" but hey.. it's all I have.
I'm going to talk to myself for a bit and use this thread as my notepad. I've been reading how an EGR valve isn't supposed to be used until after the engine is warm. That must be why there is a temperature controlled vacuum switch near the thermostat. It could interrupt the vacuum to the EGR until engine's warm. Once warm, the EGR opens with vacuum and lets exhaust gasses into the intake mix which lowers combustion temps/NOX emissions. An EGR that's stuck open will cause a low lumpy idle. I hear you can run with it disconnected without a change in engine performance... but you have to deal with bad karma for polluting.
