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Weird Issue 1975 280z (any input helpful)

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Weird Issue 1975 280z (any input helpful)

Old 07-29-2016, 06:35 PM
  #1  
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Weird Issue 1975 280z (any input helpful)

So, heres the problem.


The car starts fine. It idles fine. It can idle all day. It drives fine at first. As soon as it warms up it starts bogging out bag while driving and is very difficult to keep running at low/no rpms. Once the car gets to a decent steady speed usually around 25 or above it runs fine.


No idea what it could be.


Here is info about the car:
1975 Base Model, 280z, fuel injected.


Straight pipe, no catalytic converter.
New fuel rail
New fuel injectors
New clips.
All cylinders are firing (they have been checked)
New fusible links
New voltage regulator
new alternator
New battery
New brake master cylinder
New fuel filter
fuel pressure regulator is attached and also a guage (reads at 30 psi's during idle)


Was thinking possibly vape lock because the fuel rail was getting hot. But, we removed the hood and drove without and still experienced the same problem.


Can vape lock still happen if the fuel rail is getting proper cooling?


Any other questions please ask. We are stumped on this one.
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Old 07-31-2016, 12:53 PM
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Is it auto or stick or converted?
Bad distributor, check vacuum and mechanical advance with a timing light. Vacuum should advance immediately, mechanical after about 2500 rpm.
The fuel pump may be weak. There is a small filer in the pump that gets overlooked, one larger after the pump and one under the hood.
Test the pump by turning on the ignition and holding the throttle open. You should be able to hear the return line in the tank. Check again when it's hot. Engine off so you can hear it. The pump only runs for a few seconds with the engine off and you have to repeat this.
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Old 07-31-2016, 04:26 PM
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It is a Manual.


We have checked for vacuum leaks. We found 4 of them, and fixed those. It does have more power but still cuts out.
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Old 08-03-2016, 05:56 AM
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You need to check that the breaker plate is moving freely by hooking up a vac pump to it with the cap off. Check your fuel pressure at higher rpm when it's warmed up. A cracked intake boot will give you problems too. The one between the maf and tb. Download the factory service manual and learn how to test the air flow sensor etc.
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