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1977 280z prepup for smog check

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Many of the jars that food comes in, like salad dressing and mayonnaise, have plastic lids that can be drilled and cut for use in the garage.  I had one that I set up as a liquid trap for when I wanted to pull nasty liquid using a vacuum.

Anyway, The shape of the device seems to lend itself to something like that. 

Here's a similar one, except it has a metal lid.  Just run your electrical wires in the other port, seal it well, suck on the hose, and you're at high elevation.  Don't let the cops see you though...



Edited by Zed Head
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The odds are in your favor.  But there is a risk.

You might hear a slight change in RPM.  6% less fuel.  If you do, then just keep the plug jumped and go get tested again.  You're so close before, it should pass.

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8 hours ago, Zed Head said:

So you're saying that he should trust what the FSM says and go ahead and short that switch?  Assume that a direct short is fine and won't harm anything. 

Yes, that's what I'm saying. I have no reason to believe that thing is anything other than a simple pressure (or lack thereof) switch.

If it were my car, I would put that device in a jar and try to draw a vacuum on it and see what happened, but if I could not get that to work, I would just short the connections and see what happened. Unfortunately I don't know if you would hear or smell any difference... The effect may be subtle enough that you might only be able to see it with diagnostic equipment.

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Well, got the ‘78 fuel rail and regulator.  It actually a bit worse.  Without solenoid/cranking the car, 42ish PSI and 34PSI on idle. 
another thing “weird” is that open the oil cap, the car takes few seconds before it starts to stumble and die.   Also, the original, ‘77 fuel regulator, the vacuum hose to the intake manifold was not sealed completely on the intake manifold.  There is quite a suction on that hose too.

also, I did jump the wire on the altitude switch.  I can’t tell the different on the engine sound/exhaust smell where the jumped wire work or not.


the exhaust still smell a bit of gas for sure.

is there anyway to lower the pressure? Change the hose to be smaller from the fuel filter to the rail?




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Come to think of it, the vacuum hose to the original FPR wasn’t tight enough.  That explains when I open the oil cap, rpm lower but not stumble and die.  With the tight vacuum hose and the ‘78 FPR, open the oil cap made the engine stumbled and die.  However, oil dip made no different.  Does that means the vacuum now tight? No more leak?  I’ll have to see the CSV once more time 

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Ladies and Gents,

it’s a wonderful day today.  My Datsun has finally pass the smog test.

Last night I readjusted the valves and was careful to have all within the same “resistance” when sliding in the feeler.

Took the fuel pressure test again using different rental showed 30psi at idle... drove the car at least 30 miles on freeway before brought her in... the rest is history.


much appreciate all the suggestions and guidances from everyone.  We will deal with this again in 2 years . 😉 but for now I’m a enjoying it.

more other little things here and there but at least I can drive the car now.




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