It definitely helped.  I had it on a 20 minute timer and if I turned it on I had no problems when I came back, if I forgot and came back in the critical window, it always had the problem.  But I had a hose with holes directly over the injectors to direct the air right at them.  Then I added an aluminum fuel rail with different injectors and solved the problem completely (I thought) so I removed the fan.  Adding others' experiences in to the mix suggests that the larger fuel volume and the better heat transfer of the aluminum rail keeps the injectors cool.   Fastwoman suggested heat-pipe technology as a reference, like distillation but for the purpose of removing heat.

 

Things were fine unit just this winter when the problem came back, probably due to fuel changes.  So I added insulators to the injectors and it dropped it to about a 2% level.  Occasionally, after a long drive and a stop I'll get a second of roughness.  But it goes right away.

 

Everything points to hot injectors.

Where does one get a pre-drilled aluminium fuel rail for our cars? TIA

This guy seems to be the most popular for finished complete rails for the L6 engine.  He offers a variety of fittings from 11mm to barbed, along with a gauge fitting if wanted.  Check the last few posts to see how to order.

 

http://forums.hybridz.org/topic/99098-pallnet-fuel-rails/

 

And a few of us have made our own.  You can get stock from Ross Machine Racing on eBay.  If you're not worried about finish sometimes he sells dinged stock for a discount.

 

http://stores.ebay.com/Ross-Machine-Racing

I'm thinking that I spent about $50 making mine.  Two feet of the aluminum stock from Ross that Zed linked above, two taps and the brass nipples.  You'd definitely need a drill press and check for levelness between each hole you drill.  I didn't and one of my injector bungs is a little crooked but after hooking everything up, you can't tell. 

 

I sprayed it with high heat clear after a light sandblasting.  Turns out it was easier than I thought.

 

 

Just found another reference to hot-start from the 1981 280ZX Turbo review.  Surprised I didn't catch these before, I've borwsed through most f the articles.  This one is with the cooling fan.  From May 1981.  Note that they didn't report actually hearing the fan run.

 

"we found that cold starting and driveability were very good but the the engine wasn't overly eager to start following a hot soak, and ran tentatively for several seconds before clearing out.  An auxiliary cooling fan actuated by coolant temperature and positioned to blow cool air over the fuel rails is supposed to minimize the problem, but it obviously isn't a cure-all for every hot-soak condition."

hr369 Where in the engine did you place the z x injector fan? Would you please give more info on the installation?

I first need to find out more why my '76 280 Z is having problems, but for sure am interested in your solution.

Thank you

Jai, I think that fan will mount up to any 280Z motor.  There might be some interference with the oil pressure sender.  You'll also need to cobble up a thermostat to control it.  I don't know how that was done in the ZX.  I suspect you'd use a cheap bimetal switch to actuate a relay that would switch power to the fan.  But it won't be completely plug-n-play.  You can see the fan and its cooling ducts wrapping over the valve cover in this photo:

 

https://www.bing.com/images/search?q=280zx+engine&view=detailv2&&&id=B70D7D444A06F07E5F1DA629E44CEA88EC4E8C74&selectedIndex=9&ccid=ZzOC9W8y&simid=608016328603668167&thid=JN.Erq1JsMe4q6j1zR7rC2qBg&ajaxhist=0

If I remember right, there may not even be a temp sensor for the injector cooling fan circuit.

When the ignition is switched off, it activates the fan and a timer allows it to run for approximately 13 minutes.

I think I discovered that when I was doing some work on my turbo car with the engine cold & turned the ignition back off, the cooling fan activated.

A look at the ZX FSM wiring diagram should show the circuit.