I noticed the other day that my car didnt even have the vacuum hose from the intake manifold to the vacuum switch for the hood louver. One of the holes of the F connector on the manifold had been capped off. I took the cap off and put a hose from it to the vacuum switch but I wasnt sure it was working correctly.

Today I decided to connect a light bulb to the solenoid connector and everytime I disconnected the vacuum hose, the lightbulb turned on like it should. I connected the solenoid back where it belonged and disconnected the vacuum hose. It would either move very little or not at all so I have come to the conclusion that it's dead. Any solenoid replacements available?

I did notice something weird when I connected a vacuum gauge to the hose going to the switch for the hood louver solenoid. At Idle, the vacuum was around 18 in.Hg No matter if I give it full throttle or more than maybe 1/4 throttle, the vacuum would go down to almost 0 in.Hg and immediately climb back up to 18 in.Hg. Is this normal? Should it, in theory (dont want to test it out lol), the vacuum stay at 0inHg if I held full throttle?

Since the solenoid (and light bulb) where only energized for a split second every time I hit the throttle I dont think it is normal for the vacuum to go back up instantly. Wouldnt the vacuum need to hold at 0hg (or very low) for the whole time it is at full throttle in order for the hood louver to stay open?

 

While free-revving in neutral, there is little engine load, so vaccum recovers very quickly as RPMs build quickly. With a load on the engine (moving the vehicle) the vacuum will stay lower while the engine builds RPM (and vacuum) more slowly. While the vacuum is low, the switch should remain closed, but I don't know the specification for the precise vacuum level to actuate the switch. It has to be something above 0" Hg, however, and I would guess that 7-10" Hg would be an appropriate switch point. .

 

Thanks for your reply. I think it's the solenoid that is burned up. Is it possible to repair it or get a replacement (other than a rare junk yard find)?