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problems with a few different areas of the car. running poor, no gauges

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so i purchased a 77 z in january and have been just lightly working with the car trying to fix the years of neglect and trying determine if the problems im facing could be related or if i just have a few multiple.

also ive been sifting through the posts on here and cant seem to find answers to what im trying to fix. so im posting a new thread.

so to start off this car sat for at least 3 years, runs and drives as well. however running is running but not running well. the car has a poor idle and has quite a bit of hesitation. until reaching about 2500 rpm. and also backfires. exhaust and intake.

when the water temp sensor is unplugged it runs a lot better with little to no back firing. but does have an even worse idle. but has no hesitation when the throttle is pressed. ive been looking into it and thought maybe its the afm. however it seems to be working properly and i also figured the water temp sensor wouldnt effect the afm that much so ive begun to stray away from the afm as a likely culprit. also noticed that the spark plugs are all black which i have cleaned a few times since i purchased. which leads me to believe that its running rich. this is something that im wondering is related somehow. none of the gauges aside from the speedo tach and voltage work. all read 0. i have replaced the sending unit for the temp. and have checked the connections and all seem to be fine. checked all fuses and none are faulty. figured before i just started dumping money i would ask and see if anyone has an answer to my problems or problem. thanks!

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i don't have any. answers to your questions.Has the gas tank,fuel lines been cleaned and have you replaced the fuel filter, also any vacuum leaks. Check the easy things first.

Just for thought the Triangle Z Club is located in Raileigh NC. Great bunch of guys.

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I would,

1st, put a filter between the tank and pump, Z Car Tech Tips Fram G3 Filter Installation, then a NEW filter up front behind the radiator on passenger's side.

2nd, clean up the grounds around the motor, http://atlanticz.ca/zclub/techtips/electricalconnections/index.html, then a NEW set of NGK BP6ES

3rd, adjust the valves. very easy with the proper tools, do them cold first. https://www.google.com/webhp?sourceid=chrome-instant&rlz=1C1BOFA_enUS494US494&ion=1&espv=2&ie=UTF-8#q=adjusting%20valves%20280z

4th, borrow a vacuum gauge from parts store or buy one and check the vacuum, http://atlanticz.ca/zclub/techtips/vacuum/

5th, check your fuel pressure. Borrow a gauge from parts store or buy one at Lowes, Shop Aqua EZ Pressure Gauge at Lowes.com, get the fittings and "T" it in a fuel line.

6th, pull the connectors off each injector to make sure they're firing

7th, put a mirror under the intake manifold where the EGR mounts and look for soot from a loose fitting tube coupler. Recall from Nissan about this issue back then.

Looking back I would adjust the valves 1st if you haven't already, it really makes a difference. Make sure all the vacuum lines are good, especially the one going to the Fuel Pressure Regulator.

This will help immensely, http://atlanticz.ca/index.php/tech-tips.html

Have fun!



Edited by siteunseen

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Siteunseen's list is a good one. I think you can assume this car has MULTIPLE issues that affect how the engine runs. I think you would be doing yourself a disservice to approach your engine's issues as though they came from a single cause. The best approach with an engine like yours is a shotgun approach: Go through the thing from one end to the other, checking and verifying everything, cleaning or replacing where necessary. Just assume everything is bad until you can verify it good. These engines are actually rather simple by today's standards, so it will take less time going through all the potential trouble spots than picking away at them one by one, hoping that you will find THE reason your engine isn't running right. (Again, I can almost promise you there is no "THE" reason. There are multiple reasons, after this many years of neglect.)

I would add to site's list the following:

-- Download a free copy of the official Nissan Factory Service Manual for your year/model of car from xenons30.com. It is the most authoritative source of info on your car, and it's actually a very good manual. And if you hate electronic manuals like I do, buy a paper copy off of Amazon or ebay.

-- Replace every vacuum line. Don't just inspect them; replace them. Don't forget the HVAC control vacuum lines. You may need to correct some incorrectly configured lines, so check the FSM to ensure you're doing it right.

-- Check your "accordion" boots (especially the one between the AFM and throttle body) for cracks. Be sure to check the underside. Cracks let through unmetered air, resulting in lean running.

-- Check your brake power booster for vacuum leakage.

-- Search for the "yogurt cup test" on this forum to find a procedure for checking for any vacuum leaks you might have missed. The intake manifold interface with the head is a common leak point, due to broken studs at #1 and #6 and gasket erosion. If you've got a leaky intake gasket, obviously pull the intake/exhaust manifolds and replace the gasket (shared between intake and exhaust).

-- Renew, refresh, and probably replace every engine electrical connector. You can get new connectors on ebay. Don't forget to clean up the injector drop resistor connections (beneath brake MC).

-- Remove your distributor cap, and rotate the breaker plate. If it sticks and binds, either fix or replace the distributor.

-- Replace ignition parts: distributor cap, rotor, wires (use NGK), and plugs (also use NGK).

-- After you've addressed these "shotgun" items, run the engine for a while with fresh plugs, and then read them. Do they all read about the same? If not, you may have injector issues (e.g. clogged).

-- After you're done, the engine may still be running lean, due to old age issues with the ECU. There's a remedy for that, but let's only discuss that after you've verified all the other stuff.

Edited by FastWoman

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The 1980 Fuel Injection Guide from xenons130.com will help also. You'll need a multimeter.

XenonS130 - S130 Reference

Looks like you're working from a tiny phone screen though so life might be difficult. Thanks for the periods, they eased the pain of reading your post.

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That link I posted doesn't have a valid path to the valve adjustment tip. It's really easy and clears the mind for a few minutes, you'll enjoy it one day.

Hers's what you need, 17mm crows foot socket, $20 for a set of metrics at a chain parts store; 14mm open end wrench; feeler gauge set; 10mm socket.


You can put your car in a high gear and roll it to move the cam lobes or get a 27mm socket for the front pulley, turn motor clockwise,. or a remote starter $15 at chain parts store. I prefer the remote starter because I have to raise the engine bay of the car up to waist level, hurts my back too much bending over. The 27mm with a pull handle is kinda difficult with the fan and all or getting under the car to pull it. If you use the remote starter don't pull the trigger, put the handle in one hand and bump the trigger into your other hand.


Make a template? with the valves and the clearances written on it, COLD is Exhaust .010 Intake .008, HOT .012 Exhaust Intake .010


Remove the valve cover and plug wires.


Put a towel over the fender and put your template under the wiper.


See which lobes high point, the smallest part of the tear drop shape, are coming towards you on the passenger's side. Our motors are sitting tilted to the passenger's side so be sure and line the tear drops top up with the center of the cam towers, there's 5 of them that the cam goes through, I made a center line with a Sharpie when I realized the motor wasn't centered in the bay.

When the point centers up top slide the correct feeler gauge in between the cam and the rocker's pad. If it's supposed to be .012 do what they call the "fits and doesn't fit" method, if a .013 won't fit it's good, if it does and the .012 is loosely go in and out it needs to be tightened. Take the 17mm crows foot and loosen the locking nut at the base of the rocker arm. Then use the 14mm to adjust the next nut up until the feeler gauge has a drag to it coming out. See if the .013 "fits or doesn't fit". When your happy with it tighten the 17mm locking nut and put an "X" on your template. Move on to the next lobe coming up, it doesn't have to be in order.

Before you know it you'll be done.


Edited by siteunseen
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