urbtsx

Update: Haven't been around much, finally found a tech who seems to have solved the issue. The guy installed a potentiometer. It's a small adjustable resistor that enables us to change the lean/richness. Car runs beautifully. If anyone has questions let me know. this maybe a good place to start for the potential issues that the Z'a seem to have. After going through a slew of other suspicions that were not causing the main stuttering pre fire issue. Thank you to everyone for their time, advice and comments. I'm hoping this has solved the issues.

Not a problem zedhead, no offense taken. I'm just listing all the things we notice, mainly to "think out loud". Checking fuel pressure shortly Sent from my Commodore 64 using Tap and Talk

Quick note- we ran the car for about 5 mins and after shutting off there was pressure in the gas tank - upon opening the gas cap air flowed out quickly. Sent from my Commodore 64 using Tap and Talk

If I sound happy it's because we're making progress. We are by no means mechanics, but have general knowledge and passion for this car. It's my dad's and I'm helping him so we can get it running - it drives well, just the sputtering and dying issues I mentioned above; so I can drive for my wedding next year. Yes it has 7800 miles, it is rarely driven because it can't be enjoyed because of the issues. Sent from my Commodore 64 using Tap and Talk

So we turned the distributor cap clockwise until timing was 18 which is high, but until the pressure reading on the vac gauge was 16.5-17 which apparently is nominal operating psi. Here's a vid with idle and throttling and it seems ok. We've reduced and or eliminated the pop in the afm...not sure if we've solved the issue or not ...? One website I went to said "on throttle, hitting 0 and then up to 23 is diluted oil or worn rings" Secondchancegarage.com https://vimeo.com/142011619 EDIT: forgot to mention we have smelled unburnt gas always when driving it or idling. And now that we've done all this we STILL smell unburnt gas EDIT 2: we retarded the timing back to where it was before all this, and we got the pop sound. It was only eliminated with advanced timing...

Just ran a vac test. Will try to get more this weekend. Getting the fuel pressure test kit tomorrow. Removing the gas cap does nothing at idle. Sorry for the hasty response. Managed to grab this before heading out. Here's the result of the vac test. https://vimeo.com/141966956 Sent from my Commodore 64 using Tap and Talk

The car is a 1977 with 7800 original miles. Everything is completely original on the car, except fuel filter, inline fuel filter, spark plugs and wires, distributor cap head. We've tried adjusting timing. We've searched for vacuum leaks with water spray but found nothing. The gas tank seems to have no rust in it. It's been an issue since we bought the Z in 2008. It runs well, but as it heats up it idles rough, the intake pop happens, it back fires, sputters and dies sometimes. Sometimes it idles nicely at startup. Pressure builds up in the gas tank and you have to release it through the gas cap and it helps to run smoother. I hope that helps. Those are the main problems. Sent from my Commodore 64 using Tap and Talk

Here's an updated vid closer to the intake. https://vimeo.com/141864898 We're going to try the AFM cleaner - as it's the easiest solution so far. If that doesn't help we'll try the yogurt cup test. Sent from my Commodore 64 using Tap and Talk

Thanks for the input everyone. I'll get another vid of the engine and see if that helps. I'll check the hoses and I'm searching for the yogurt cup test after I post this. Thanks!! Sent from my Commodore 64 using Tap and Talk

https://vimeo.com/141010856 Anyone have any input on this sound. I'm not sure if it's the afm flap, or if it has to do with running lean/rich. It's been idling weird. We've replaced the spark plugs, wires, cap, the injectors are all working (I felt the vibration). Any input greatly appreciated! Sent from my Commodore 64 using Tap and Talk