Greetings, Newbie here trying to help out my son with his 99 S-10 Blazer 4wd. The truck has been showing codes PO442, PO410, and PO300 and desperately needs to fix these issues soon to comply with his state emissions test. This forum has been very educational and I've read and done searches and we have found most of where these components are except the vacuum hose routing.
We took off the smog pump and water came out of it, so we are going to replace it, and we are going to attach the various vacuum hoses up as well but can't find where they go and a routing diagram would be very useful. We found that there are hoses that go to the 4wd from under the battery, and we'll hunt that down, but first we need to connect the hose that's coming from the pump itself, it seems that it wasn't connected and don't have a clue as to where it goes. We got underneath it today and lowered the spare and made sure there were no broken lines/hoses going to the charcoal canistor, or the valve and he already replaced the gas cap, plugs and wires too. Any help from more experienced folks would be greatly appreciated especially with pics, thanks.

 

There should be two vacuum lines going to a solenoid on the pump itself. One line goes to a plastic shutoff valve in the pump output hose, the other is a vacuum source. Looking at the two fittings on the solenoid I "think" left is valve - right is source. Line from 4WD actuator goes to a solenoid on the firewall under the hood (out in the open). Other line from that solenoid is source. Your vacuum source: by the master cylinder is a collection of vaccum lines. From the engine on the drivers side is a line (take the air intake off the top of the motor to see this) then a T-fitting. One leg of it supplies vacuum to AIR pump you're replacing other leg has a line with a B/W check valve in it. That connects to a T-fitting, one leg connects to another T-fitting. The legs on those fittings supply vacuum to a resiviour (rubber line disappearing into drivers fender), 4WD actuator, heater controls (plastic line).

 

Anyone got a pic of the pump hook up. I'm having problems with this thing also, might have a hose crossed. I replaced the pump and it still throws a code. Emisions has gone to just plugging into the computer and if there is a code then they fail you, then suspend your license and you can't renew your plates either.....

 

There really isn't much you can screw up. Is the AIR pump running? Do both of the check valves hold properly? Did you replace the solenoid valve? Does the vacuum line to the solenoid valve from the engine have good vacuum?

Here is a little diagram showing the pump and ancillary components:

 

If your pump was bad, did you also remove your battery and check the 30A fuse in the fender for the AIR pump?

 

Thank you, now we can start to connect all that was not for who knows how long. We were anxious to get this fixed due to emissions test worries, and just recently found out that any vehicle 10 yrs old and older is exempt! However knowing where to make these connections will enable us to address the 4WD issues, and the drivability and hopefully clear the codes, thanks again guys.

 

Pump is running but still throwing code. Inlet hose is pulling air in. Pump is different from that diagram.

 

Pump may look a little different, Chevy had a water ingestion problem and might've redesigned the pump? You'll get a code if it can't turn the pump off too. Is it on when the key is on but engine not running? (you didn't say when you felt it drawing air). If any of the hoses are melted running to the exhaust manifolds are melted - pump air is going to the atmosphere instead of into the exhaust system and you'll get a code and you need to replace the check valve on that side. If that plastic valve on the pump outlet hose is bad it won't let the air through. In the relay block in the fender is the 30A fuse for the pump, a relay for the pump, and a 10A fuse for the solenoid on the pump, if the 10A fuse is blown the solenoid won't let vacuum go to the outlet valve. BTW what is the code?

 

Code is PO410. I replaced the pump, other one was full of water. Pump is running when the engine is on and drawing in air thru the inlet tube, I need to test it when the engine is off key forward. There is a cut in the inlet hose at the bottom of the fan, but don't think it will effect it. Might get water in it though. Maybe I should replace that check valve also. Didn't know there was a fuse in the relay either, checking them next. Mine has two vacum going to it also, might have them crossed.

 

The image I posted above shows the proper port location for the line from the solenoid to the shutoff valve. The other port should go to the vacuum supply from the engine.