BoldUlysses

I have an inline fuel pressure gauge installed on the rear carb line. Reading fluctuates between 1-3 psi at idle. I may rebuild the pump again if my plan of attack doesn't work... As mentioned above, the dying started with the previous pump, and I replaced it, and there was no change in the car's behavior. I guess the previous pump could have been bad, then my rebuild kit was faulty, but that seems unlikely.

The fuel lines are not new, but as mentioned, they've been blown out MANY times... The tank was cleaned & resealed with the POR-15 tank restoration kit about 12 years ago as part of my effort to get the car running again as a baseline. The car drove many miles after resealing the tank. Took me to work & back one day (30 mile round trip), and on several trips around the area before I parked it for the body & interior restoration. I'm going to bypass the filters and see if that helps, if not, then I'll bypass the lines (I'll run hoses from the tank to the pump & zip-tie them underneath), and if that doesn't work, I'll do what you suggested & rig up a temporary tank. I rebuilt the stock fuel pump as a diagnostic measure. I had an aftermarket replacement on there before. The car behaves exactly the same before & after the rebuild.

OK so here's how things went, roughly, earlier this evening: Lots of cranks to cold start car, indicative of float bowls having to fill from having run dry yesterday. Let car warm up for a few minutes, idle not great. Choke off. Drive it up and down the cul-de-sac. Starts missing, bucking at anything over 1.5K rpm and the lightest of loads. Pull back into driveway, remove the gas cap to eliminate the possibility of the evap system being clogged/misrouted. Car idle seems to smooth out a bit, though this could just be coincidence. Let it idle for a few more minutes, then take it out in the neighborhood again. Immediately acts like it wants to die. Manage to coast it back into the driveway. I put the timing light on it and crank it, no start. Timing light flashes at regular intervals. Check the fuel filters. Rear one is nearly full, but engine bay one only has about 1/4" of gas in it. Let the engine cool just a bit while I remove the fuel hardlines above the manifold and give them a good cleaning & blow-out (not b/c I think they're the issue; just b/c I hadn't done it). Reinstall hardlines and go to start the car. Cranks & cranks, but the engine bay filter is filling now. Finally starts, but I'm out of time and pull it back into the garage. Conclusions: Pretty sure it's not the ignition, since I have spark the whole time. I don't think the evap system is an issue, since it died while the gas cap was off. The full rear filter & nearly empty front filter would seem to point to a clog in the feed line, but I can't tell you how many times I've blown out both the feed & return lines... Still stumped. Any ideas appreciated, as always.

Yeah I wasn't super impressed with the fitment of the kit when I got it. Actually had to get a guy at work to cut a notch in the mounting plate to clear the wires when the timing is advanced. And the round rubber grommet doesn't fit the rectangular notch in the distributor body. I don't have a spare plug lying around, but I could use my timing light. Will give it a shot this evening.

So this is a follow-on to this post, but i didn't want to clutter up my resto thread with too much troubleshooting, and I thought a standalone thread might be more helpful for others battling the same issue. Long story short, my '72 240Z starts and runs fine initially, but dies after for 10-15 minutes, and won't start again for minutes at a time. It's gotten me temporarily stranded, fortunately not too far away (yet). Fuel system: Tank cleaned out Fuel lines blown out New primary filter, and secondary inline filter installed near tank Fuel pump recently rebuilt Carbs rebuilt by ZTherapy about 12 years ago, float bowls properly wet-set Ignition: Stock coil Timing set at 10 degrees BTDC Pertronix points replacement kit installed I've been assuming it was a fuel system issue, but now I'm starting to think it may be ignition-related. It's been a couple of years since I installed the Pertronix kit, and I believe it said I didn't have to use the condenser, so it's not on the side of the distributor. Is this an issue? What else could be going wrong ignition-wise? Here's the wiring to the coil area, can someone check my work? Thanks much.

Yeah it really sucks to not be able to actually drive anywhere. Last time it happened the car died and coasted to a stop around a blind corner of a busy two-lane road. A couple of local boys stopped and were going to push me into the subdivision, but fortunately, I was able to get it to catch just enough to make it there, so they didn't have to. Let it sit for 4-5 minutes, then I got it to start and (barely) run again, enough to make it home. Very embarrassing. Sigh. OEM coil, Pertronix points replacement, wired up in the dist. Maybe it's ignition-related? Found this here:

Actually there are quite a few threads discussing disparities between the front & rear bowls leading to running issues... I decided to go with 21mm for the front and 19mm for the rear. Took a couple cranks; I was reasonably close. Final float position: I think I have 1 washer under the Grose jet; I could have probably removed it, but I don't like the idea of the jet grinding its way into the underside of the float bowl lid without a washer, so on the balance I prefer to just position the float. Final gaps to the underside of the lid: Front: .240" Rear: .215" 2.5 turns down on the jets; it cranked & started fine, and I gave it a basic tune. As evidence that the float level difference was accurate: My first Uni-Syn readings from both carbs were identical; that's never happened before. Drove it around the neighborhood and got it warmed up, and settled it down to a nice 700 rpm idle. A little more tinkering, and I decided to drive it around the neighborhood again. Everything was going fine until... It died. Again. Fortunately I was able to coast back into the driveway and pull it into the garage on the starter. Both filters: Full. It can't be gunk in the tank. It always happens about 10-15 minutes into the running session. Surely it's not something like vapor lock in the hardlines above the manifold? Could it be ignition-related? Bad coil overheating and then shutting down? I'm so frustrated. I don't know what else to do except to keep looking for blockages; going to pull off the hardlines & clean them out tomorrow.

Thanks. Seems like a pretty straightforward method. 3 questions/remarks, though: I don't want to put a Sharpie line on my carbs, so I'll have to figure out an alternate way. Blue tape, maybe. It will be a challenge to get a straight-on view of the float bowls when they're installed on the car. Will have to figure that out. Do you account for the different float levels needed for the front & rear carbs? I tried the micrometer method, but it's basically impossible to see the fuel level relative to the top of the jet in order to set it properly. Also, the fuel level is supposed to be .426" from the top of the bridge, but that's right about where the jet bottoms out, making adjustment in that range a challenge. Will keep trying.

Me too! To be clear, when I mentioned the "micrometer technique," I didn't mean simply measuring the gap between the top of the float and the bottom of the lid like I did above, I meant actually measuring the height of the fuel in the jets: https://www.zcar.com/threads/setting-carb-float-levels.423305/?post_id=2790569&nested_view=1&sortby=oldest#post-2790569 Do you have a link to the wet-set clear tubing method?

Got it running again. It took a LOT of cranking; those 2 inline filters took a while to fill. I installed the fuel pressure gauge on the rear carb line, like you guys suggested. Registered 3 psi at idle, which I think is OK. Now that the float bowls are full, I'm going to try to baseline the fuel level in the jets using the micrometer technique. Wish me luck, haha. Side note: My dad did a great job refinishing the steering wheel. It took a LOT of elbow grease.

Peekaboo.

^Hoovie's going to make a lot of money on his Bentley Arnage owned by Jean-Claude Van Damme whenever he decides to sell it...

As long as it's clean—and it is! I think the "new" bay looks great. Only thing I'd consider changing would be the upper rad hose; the red silicone (?) sticks out too much.

Ah good tip. I'll change it; it would be a cleaner install and allow me to monitor the gauge while I'm on that side of the car. Thanks for the tips. I'm working with what ZTherapy provided when they rebuilt the carbs (for the 2nd time) 10-odd years ago. It looks like the pivot point for the floats is located differently b/t the front and the back carbs. I guess the danger is the float hits the back of the bowl and can't pivot enough to open up the jet... We'll see tomorrow. And thanks for the insight about doing a wet set. Depressing to realize there's more involved in getting this thing set up correctly given my motivation is where it is, but I'll just have to knuckle through it.

Had to take a step back for a couple of weeks 1) to get some other projects done and 2) for my own sanity and motivation. Dug back into it today. It's been raining all day here, so I didn't get a chance to test drive it. Can you guys check my work? Found some gunk in the last-chance filters. Front: And rear: Got it all cleaned out. Grose jets have 1 washer on the bottom: And I set the float heights to 9/16" (.5625). Front: and rear: Fresh float bowl gaskets also. Hooked up a fuel pressure gauge thusly: Reset the mixture screws to 2.5 turns down. Assuming everything looks good, hopefully I'll get some insight when I'm able to drive the thing again.

According to the ZTherapy VHS tape, someone did independent flow testing of a number of intake/air horn combinations, and the stock air horns flowed the best. Nissan got it right the first time, looks like.

Its proportions remind me of the C8 Corvette's; that is to say, not great. If you're going to go mid-engined, the same styling cues won't work like they did on the front-engined car.

I bought an inline fuel pressure gauge, but I haven't used it yet. Will get it hooked up. The carbs were rebuilt by ZTherapy about 10 years ago and the car's probably only been driven 20 miles total since then, so I don't have any reason to believe the floats have moved. I'll check though. Yes, the carb pistons both move freely, and the carb chokes are both working fine. I'll check the fuel filter screens in the banjo bolts. Another potential clue is that the problem seems to worsen the less fuel I have in the tank. The gauge shows about 1/3 full at the moment. Got that sinking feeling like I may need to drop the tank and have it reconditioned after all. Maybe it just needs more protein instead...? 😉

Gradually. It feels like the float bowls are just running dry, like it runs on 1 carb, then 0 carbs. It always seems to happen on an incline as well. Weird thing is that it didn't do it at all over the weekend, and I drove around the neighborhood a good bit. And several days prior to that, I managed to drive it a couple miles to CVS and back, and then did a short loop around a couple of back roads. I thought I had the problem sorted with my fuel system overhaul... Guess not.

Added a little vanity: and a little utility: ...over the weekend. Of course, like a moron, I attached all the splash pan screws except for the rear ones. Note to self: Secure those FIRST next time. I also got the PerTronix module reinstalled. See: https://www.classiczcars.com/forums/topic/67639-pertronix-points-replacement-does-this-look-right/#comment-644306 * * * * * * In other news, I'm very discouraged about the car's state of tune. I have spent HOURS with the fuel system and carbs trying to get it sorted, and it still just died on me on a trip around the neighborhood. Just cranked and cranked and wouldn't start until I gave the fuel filter in the engine bay a good shake. I've blown out all the fuel lines, rebuilt the pump, filled the tank with fresh ethanol-free 93 w/stabilizer, added a supplemental fuel filter near the tank, ensured all the hose clamps were tight, replaced the main filter twice and the stupid thing still insists on dying randomly. Furthermore, I cannot get the idle to behave. I have a Uni-syn and I've been doing everything by the book, going around and around and there's always a slight miss. I just can't trust it. Which sucks, because the whole point of this exercise is to be able to, I dunno, drive places without the car paperweighting itself mid-trip. /rant

Final solution: Got one of the machinists at work to notch out a clearance recess in the plate. Retarded: Advanced: Not sure why this wasn't present from the get-go. Also, I had to trim off about 1/2 of the grounding wire screw since it extended all the way through the plate. And as mentioned above, the grommet for the wires exiting the distributor housing doesn't fill the oval-shaped hole, raising the very real possibility of water ingestion if I'm not careful. Again, not impressed with the attention to detail in this kit. I shouldn't have had to make all these modifications just for it to fit and work properly.

Quite the getup you have there. Do you have a wideband O2 sensor and EGT gauge? Those are going to be very helpful to ensure you're not running lean under boost. Still not sure about the turbo. I can imagine it would be stiff when you got it back from the rebuilder b/c of the assembly lube, but that should be flushed out the first time oil pressure comes up...

What model/year Z do you have? Not sure about the stock fuel system being able to handle it; you almost always need to add fuel when adding a turbo, otherwise you risk running lean under boost and grenading your engine.

Yes you need a load on the engine to generate boost. All the turbo cars I've owned/driven didn't develop boost until well into 2nd gear on the road. Also the compressor wheel / turbine spun freely by hand. If all you need to do to get it on the road is to reassemble the intake, why not test drive it?

It's a shame the 240Z relay kit doesn't work for the 280. I wonder how different it is? https://www.thezstore.com/page/TZS/PROD/classic10d23/12-4651 I have the parking light relay kit installed on my 240 and it was totally plug-and-play and reversible.