awdjunkies

(May not be related but)How is the fuel Pump? Of course the Carb. may also need adjusting and/or replacing as the others have suggested.

DROPT

im assuming the fuel pump is fine, i mean the truck runs and drives great?

DROPT

Ok guys i need some help, i dont know what this is, but i know it should be connected to something. I was able to stick my phone down there and get some pictures. also with the engine running i stuck my hand down there and it blows air out, also making a funny little pulsating sound since nothing is connected to it.

any ideas what it is? and what hooks to it?




Oh and i do infact have the wrong spark plugs what harm will this cause?

the one on the right is what the fsm calls for but i only had one of them it was left in the glovebox by the previous owner.

DROPT

bump...

andykrow

Man its been so long since I've been on a non-efi truck so this is a stab from distant memory... but that may be for the air injection system. What is feeding the air to this thing? I remember on my old carb truck there's a belt driven air pump, and then a control valve for basically turning on and off the air, which is what I'm guessing this is. IIRC applying vacuum to the control valve causes it to open up. The Vacuum switch that controls this on my truck never worked, so I put manifold vacuum directly to the control valve, which turned the air injection "on" all the time, which got me through emissions. My truck went from failing HC on the order of thousands like your last run to something like 14ppm (no joke...)

Now you need to be sure you have the right plumbing to get this air into the exhaust stream...and I don't remember at all how that worked. I think this whole thing is called the PAIR system.

Again, I'm going completely off memory from WAY back so take this with a grain of salt. Hopefully it steers you somewhere useful.

DROPT

thanks man, ive looked over the truck well over a hundred times lol, and i dont see anything else that isnt connected. my hanes manual says nothing about this piece, even in the fsm its very vague it doesnt have a diagram showing this. im at a loss right now.

andykrow

Again this is all memory but look around the back of the head. There should be a metal pipe with a check valve at the end of it, and a hose will go between the mystery part and this pipe. If you don't have that pipe look around for a block off plate. I don't recall if this connects to the back of the head or the exhaust manifold.

Again, what is supply the air you feel pulsing? If it's air injection there will be a belt driven pump about the size of the alternator but on the passenger side. Should have a hose from the air cleaner and a hose or pipe to the "thing"

DROPT

there are two hoses that come off of the smog pump, but they are both connected. i'm beginning to think that this is just suppose to have a hose going to the air cleaner?

andykrow

Yeah I think it does. So this is connected to the smog pump then? My haynes which sucks for this seems to show the "thing" having a hose from the pump, a hose to the air cleaner, and a hose to the air injection tube.

It would seem to me that your valve is bypassing air. Put vacuum directly on it and see if it stops sending air out of the air cleaner outlet (the one with no hose) which would hopefully mean it's sending air to the injection tube. I bet that gets you through emissions...