If they come off fairly easily it's time for new vac lines.

Although even loose vacuum lines can hold vacuum low pressure. As I said above, when the outside pressure increases relatively it only holds the tube on more.

But I would swap them out if they are not a nice tight fit. Also if they have been pinched for a while, maybe a slight gap has appeared.

Did you check the correct plug is on the solenoid?

 

I did check the solenoid. and there's just one plug that plugs into the solenoid. Not 2 separate wires... here's a photo I took of the solenoid and the plug. Note, I still need to remove the zip ties:

 

Is the wiring for that plug taped up like someone rewired it at some point? If so you might want to check that out first. You can unplug the connector and check for voltage. One side should have 12v and the other side should not. If you want to further test that the solenoid is working you can plug it back in and back probe both sides (one at a time is safest). When plugged in, both sides should have 12v. If that looks good, if you back probe the side that has no voltage when unplugged and jump it to ground, you should hear the solenoid switch on.
I hope that makes sense!

 

Oh also, what cappedup was talking about was the plug on that solenoid and the purge valve under it with the black plug. I think it is possible to mix those two up. I'm pretty sure they are the same connector, that's why they're color coded.

 

Quick update....This is DRIVING ME CRAZY !!!

The Solenoid in brand new but I tested the plug coming into it and here's what I found:

First off neither one reads anything with the key on the "on" position. I had to start the vehicle first. With the vehicle running, one of the leads reads between 12 - 13 Volts(this is the continuous hot), but he other one reads 6.4 volts ! ???

I thought the other one is supposed to be a (switched) ground and shouldn't it read 0 volts ???

Does the ground only read zero volts when the SAI system is activated ?? Maybe thats why I am getting that reading ??
Thanks!
Todd

 

Oh, that's power side switched, sorry!
The ground is probably bad if it's reading over 100ma or .100 vdc.

 

So, this morning I did a couple tests. During the cold start process with the SAI activated, I pulled the hose that comes from the manifold off of the solenoid and touched my finger on it hoping I would feel a suction, NOTHING! I then re-connected the hose and waited about 20 seconds to see if there was any sort of vacuum buildup in the vacuum reservoir by disconnecting that hose, again nothing! What does this mean?? Vacuum lines are bad ??

 

Just to confirm, did you take off those massive cable ties that are obviously pinching the tube and causing a leak, and then replace the badly fitting loose vac tubes with nice new ones?

 

Problem solved !!!! YES !!!

So, after all of this effort buying a new SAI air pump, new solenoid, testing the electrical system, etc. I ended up taking the entire vacuum harness off the truck and in doing so I tried blowing air through all the hoses. What I found was that I could not blow any air through the main hose that goes from the manifold to the vacuum reservoir. I though it had blockage in it. But after closer inspection I found that the plastic hose at the end that connects to the vacuum reservoir had bottomed out inside the rubber 90 degree elbow. It was pushed in too far and prevented air flow. I replaced the rubber elbow. Tested the system and bingo! All working. Now I have a perfectly working SAI pump and solenoid I need to sell on eBay !

 

Phenomenal.

Great news. These things are often on the simpler less expensive side, and this was one of those.

Always suspect the simple. Thanks for letting us all know.