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78' 280z fuel delivery issue, plugged cat?


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Hey all I have a 1978 280z I've been trying to diagnose a problem I've been having for the last month and a half or so. Lately the problem has escalated and is affecting drivability.
Fuel cuts out a lot , like it's "falling on it's face" I know it's not an electrical problem, vacuum is good, haven't done a fuel pressure test, I replaced my inline and under the hood fuel filters no change, been running fuel system cleaner for the last 3 weeks, I was starting to get the idea that maybe the catalytic converter could be clogged, but I'm not sure. I definitely think that is the problem or it's a fuel delivery issue, and would like some help diagnosing the problem. car is still somewhat drivable under slow acceleration, it is my daily driver. it also idles fine and responds to throttle normally when in neutral. also passed smog about five months ago, all of the cylinders are running slightly lean except cylinder 5 which is burning oil (per spark plug inspection). I work m-f 9-5pm so it's difficult for me to take my car in to a mechanic, any ideas would be appreciated and yes I have been using the search function and trying many things before I finally decided to make this post. I may take a day off next week to take the car into datsun alley in signal hill by my house, but until then I'll be trying to get it up an running myself. Another things is that it idles slightly higher (~200 rpms) after being driven for around 20 minutes.

Edited by Bigfat280z
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A quick way to test the converter is the engine vacuum will be low, you need a vacuum gauge to test that. Usually a clogged cat will cause a  loss of engine power, and the car won't go over 35mph. Another way to test the cat is to run the engine for a few minutes. Place your palm a few inches away from the tailpipe and feel how hot the exhaust gets. If it almost burns your palm the cat may be clogged. Exhaust from the tailpipe shouldn't burn your palm.


You seem to have some other issues going on.

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vacuum is good, and exhaust isn't overly hot, I think that the fuel pump might be going bad it makes noise when I start the car and after reading some of the symptoms of a faulty fuel pump this seems like the most logical answer I'll be replacing it hopefully in the next couple days thanks for the input. 

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