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Discussion Starter · #1 ·
My 1986 Spider Quad made a really odd sound today when I shut it off after my commute home from work. it was kind of a high pitched (but not loud) sound coming from inside the trunk area, back where the Jack is stowed. The noise went on for about a minute after I shut the engine off, I guess. This car has been running fantastic with no problems whatsoever.

Does anyone have any ideas what this noise could have been? I would like to take it on a trip this weekend, if there is nothing obviously wrong. I would appreciate any ideas!
Steve
 

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Could it be the manifold (vacuum) sensor? It is located under the right side panel - behind the right door. When they fail (leak vacuum) they make a whistle or moaning sound. But I can't imagine it making the noise for a minute after shutting off the engine...

How about the vapor recovery system? There is a one-way valve and air inlet valve and the recovery tank - all located in the compartment just forwards of the trunk. The one-way valve &/or air inlet valve can be cleaned with a squirt of carb cleaner flushed through them. If you hear the noise & remove the gas cap does the noise immediately stop?
 

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Discussion Starter · #3 ·
I couldn't tell exactly, but it the noise seemed to come from the panel forward of the trunk. I did loosen the gas cap, and the noise did seem to subside, but I wouldn't say exactly immediately.

I'll try to get it to do it again for further diagnosis. I wonder if it could have been brought on by yesterday's sudden exceptionally hot (80-degree) weather here in Maryland?

If it were a problem with either of these things you mentioned, should I try to fix it before my 800-mile round trip to Ohio?
 

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The vap system is in the same compartment as the jack behind that drop down panel.

If the gas cap had an effect, then that's prolly what you're hearing as Eric suggested.
(might have to outright remove the cap to get immediate results as loosening will indeed let air in, but can still restrict, hence it not being 'right now' when you tried)

The nice thing is bits back there can be delt with easily using a can of carb cleaner.
You simply take out the two one~way valves after marking location and orientation (it is important, as getting one backwards, or the two reversed in location will create fuel starvation and you won't drive anywhere) and give them a good flushing.

There's info in the FAQ w/pix and drawings IIRC, but the basic premis is that the metal one should rattle when shaken and only allow air to pass through one way easily and the plastic one should only allow air to pass through one way period. Neither should take more than lung pressure to blow through.

My guess is that the plastic one is your problem right now as that's the one that has an actual diaphram in it which can certainly make noise, as opposed to the metal one which is more or less just a metal check valve that can't really vibrate in that fashion as air leaks by it.
 
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