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My car is 1974 GTV 2000. Recent tune but this slow return idle just began. This will be my first look ever at the injection system, so I am searching for any suggestions before I head down a wrong road. Appreciate any help.

Keith
 

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Push hard and live
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Take off dizzy cap and spray something like Triflow around where it can lubricate the springs. Also look closely, in case you see a broken or loose spring.
 

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Push hard and live
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Squirting lubricant, $5. Knowing WHERE to squirt the lube, priceless.
 

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Richard Jemison
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Actually the Marelli distributors used springs that had insufficient spring tension to return the fly weights to "unadvanced" position. One is typically "an lengthened "U" shape connectoin that does nothing to return the distributor to "unadvanced" position.
 

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I realize Keith has solved his problem. But before I read the solution I first thought about the fuel cuttoff. Would issues with the Spica micro switch also cause this? The micro switch cuts fuel (or at lease reduces it to idle quantity) when the throttle is lifted. That should lead to rpm dropping pretty quickly, right? I am assuming no load on the engine, since a defective micro switch on a loaded engine in decel creates sputtering from the extra fuel.

One of my Alfas has an aftermarket EFI and I recently discovered this feature in the programming. It can cut the fuel completely when there is no throttle and above a certain rpm, like 1500 or so, so it will catch back on when it drops to idle. I even saw some fuel savings when I found and activated it.
 

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Having just looked into this and in fact removed the injection pump to adjust the fuel cut off switch I can confidently say it would not cause those symptoms. Even Wes Ingram advises that the spica 3d cam effectively has its own cut off and the microswitch is in effect a bonus.

You can test it by removing the quick disconnect at the fuel cut off solenoid which is on the top of the pump and connecting a test light to it. Warm up the car and then Revabove 2000 and let go of the throttle you should see the test light illuminate, then go out as revs drop further. I don’t have the precise conditions under which it is tripped but I did find that during the warm-up cycle when the TA prevents the throttle from closing all the way this function did not work.

Consider a modern distributor such as the 123 if you are in the market for an upgrade in reliability.
 
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