82 CIS Decel Valve - Question

[kstylianos]

Was looking over the CIS last night and noticed the small vacuum line from the Decel valve to the throttle body was blocked, no air can get through the hose. Took both ends off and tried sucking/blowing air through and its 100% blocked. What's boggling, is that the hose is blocked internally. There is a noticeable 'lump' in the hose
about 1-2 inches from the end that attaches to the Decel valve, looks to be a piece of plastic or something else hard blocking air flow. I'm currently replacing all the vacuum lines and was wondering if the hose should be blocked (my guess is not) and why would somebody (possibly PO) block this hose? My CIS was pretty reliable and ran well before engine tare down.

Any help would be appreciated.

[Jdub]

Probably a BB. This is a typical "fix" for ensuring no air can pass through.

If you want that line to work I'd just purchase a new one.

John

[kstylianos]

What is this a 'fix' for?

I've heard of blocking one of the ports on the back of the Decel valve to disable, but havent seen a thread regarding this little vacuum line to the throttle body. I figured it needs to be replaced, but now I'm just curious as to what blocking this line does.

[MotoSook]

Vacuum cases the decel valve to open. No vacuum to pull on the diaphragm, no by-pass..easier than plugging the big line. But if you have a leaky decel valve, might as well, block the big hose.

[kstylianos]

Thanks Guys. I found my answer on the Rennlist pages.

"In working an cars with the later model valve, I have frequently found the actuation line (small line) intentionally plugged by the owner or mechanic. The reasons for this escape me. I suppose that some drivers don't care for the slow fall in RPM caused by the operation of the valve when the accelerator is lifted at high RPM."