desertdatsuns.net

Decided to take it for a short drive. I haven't driven it in about a month, but it ran great when I put it away last month. (sounds like a for sale ad ). Anyway, I used the choke and cranked it over, after a bit of cranking (normal) it stated right up and ran smooth. Pulled it out of the garage, shut the choke off, open hood and confirm chokes are closed as mine tend to stick a bit, all good.

I was going to let it warm up a bit while I dusted it off. It idled for about 2 minutes and then starting running really rough. Tried to give it a little gas and it would stall. Started up again (very rough) tried to rev while massaging the throttle and it sounded like lots of air but not enough fuel to rev. I thought, let me check the easy stuff first.... My fuel gauge doen't work so I don't know the actual level of the tank. Ran and got 2 gallons in a can and dumped it into the tank. Started it up again and ran rough for a bit then smoothed out and ran normal. Revving... All normal. Figured, damn I was lucky on my last drive to not run out of gas....

Now the strange part... drove to the gas station and it only took 6 gallons (it was full, could see fuel in the filler neck). So if I just put in 6 + 2 from cans, that would mean the tank was half full while it was still in the drive way. Why was it running shitty, but better after adding a couple gallons?
After filling it to full, we drove for about 20 miles and everything felt normal?

Any clues or suggestions? Seems strange to me.

I know I need to fix the fuel gauge or sender. It only goes about a needle below 1/2, to 5/8 tank when 100% full. So its always a guessing game. But today was strange?

Dale, I know the specs show 16 gallons as the capacity but honestly I don't ever remember ever putting more than about 12 gallons in mine. Still doesn't explain your issue though. Would have been interesting to have pulled your float bowl lids to see if they were dry or down on fuel when it was running poorly.

Thanks Randy, I should have done that. After, I did unscrew the tops and think I'm a little low on oil for the carbs. Looks like it has ATF in them (red). I'm pretty sure that wouldn't cause the issue, but just noted it. I'm going to change out the fuel filter, I don't think I've changed it since I've had the car.
Dale

I wish I knew anything about the black magic of carbs. To me diagnosing a computer is relatively easy. Although I want to learn about carbs and how to troubleshoot I just have never been around a car with carbs yet

About the fuel gauge: Good news is that it has 2 adjustment pots to correct the needle position at both Full and Empty. Bad news is they're on the back of the gauge...

I have a 240z sender that you could test with to see if it's a gauge or sender issue.

cgsheen wrote: ↑Mon Sep 14, 2020 3:53 pm About the fuel gauge: Good news is that it has 2 adjustment pots to correct the needle position at both Full and Empty. Bad news is they're on the back of the gauge...

Thanks Chuck. Good to know.

Racerx3110 wrote: ↑Mon Sep 14, 2020 4:27 pm I have a 240z sender that you could test with to see if it's a gauge or sender issue.

Thanks Bryan. Once it gets a little cooler (shouldn't be long now) I'll get in there to look at it. May take you up on it. Thanks

Dale

I wonder if there might be a hole rusted in the pickup tube. I don't think the tube can be seen, but I suspect I may have a similar issue on my 75.