on the 305 EFI its located direct center underneath the intake plenum. have fun. its a nightmare.
Under the hood, they are plugged into the Intake plenum by the MAF.
Not sure what engine you are working on but if you are using a new gasket there is no need for silicone unless the directions included with the new gasket require it.
if you mean it doesnt crank long enough to start you probably need a battery. i suspect that the battery is dead because it takes so long to start. long crank times on these engines is usually caused by a bad cold start injector (found in the intake plenum on the passenger side, it has a small diameter steel fuel line and a 2 wire plug connected to it. held in place by 2 10mm screws) or the cold start injector time switch (found in the back of the engine behind the intake plenum, it sits in an aluminum casting that holds other water temp sensors and has a blue plug with 2 wires on it). replace these 2 items and you should be fine as far as hard starting goes.
underneth the intake underneth the intake
The plenum is the intake manifold.
The intake plenum is simply the top of the upper intake manifold, where the throttle body is attached. It is made of black plastic.
Plenum is another name for the upper intake manifold.
The plenum is the upper part of the intake manifold.
It's directly underneath the plastic cover that covers the top of the engine, the plastic cover pulls off and the intake plenum is underneath it.
The intake plenum on a V-6 or V-8 is bolted to the top of the intake manifold. It has the throttle body bolted to it. The throttle body houses the throttle plate and is located at the end of the tube that starts at the air filter housing. Sometimes the intake manifold on a 4 cylinder is referred to as a plenum. It works the same way and is found in the same manner. Look for the air filter housing, then follow the hose past the throttle body to the intake or plenum.
Just the plenum.
Under the upper intake plenum. You have to unbolt the throttle body and the take out the upper intake plenum bolts to remove the plenum...(the part that says 3.1 Multi-Port). Once you have it off you'll see them.
It's on the left side of the intake plenum looking at the cars front. It's screwed sideways on the left side of the intake plenum with a hose coming right off of it. It's not visible unless you remove the upper and lower plenum.
You have to remove the intake plenum air chamber to get to the 3 plugs against the firewall. It requires to buy intake plenum gaskets and go ahead and replace the PCV hose on the back of the plenum. Need to get from the dealer. Gaskets also from dealer.
intake plenum
It is on the underside of the intake manifold