F451

I hear you on the logic of a blockage, that would be the logical, and first thing to check once you determined you had a fuel starvation problem. And I could be wrong on my diagnosis, but I don't think so. And correct me if I'm wrong here, but the 240Z has one mechanical fuel pump, run off the engine, right? So, its a vacuum/suction system (for lack of a better term), correct? Once you have a crack in the rubber hose, you can draw in air, lose vacuum/suction, then lose fuel flow. No blockage, but no fuel flow either. In my particular situtation, when I replaced the cracked hose, I could run the car down to "E", no stalling problems what-so-ever. Before replacing the hose, the stalling was like clock work once the car went below 1/2 tank. And I think having 1/2 a tank of gas would be more then enough to allow any obstruction(s) to be washed around in the tank, thus allowing the car to re-start (which it never would) but I could be wrong. I also should mention that during my previous troubleshooting attempts, replacing the fuel filter (which looked fine) was one of the first things I did. After replacing it, filling up that thank, and running it, I of course inspected it the next time the car stalled out (and a number of times after that), it looked fine, no dirt, sediments, etc, that I could detect. Replaced the hose, the car never did it again. Never had any fuel starvation problems again, so if it was a blockage problem, you would think it would occur again once the tank got low, but it never did. Hence, I concluded it wasn't a blockage problem then, and I don't believe its one now. Well, I'll be keeping an eye out for anyone that may have experienced this, and fixed it in the same way. Would be interesting to hear if anyone else had this strange cutting out below 1/2 tank problem. I can't believe I'm the only one, and to have it happen on two different 240Z's, in the exact same way - 20 years apart, and to have the exact same fix work both times, seems pretty low odds to me. But perhaps I'm looking for the amazing and I didn't fix anything (except replace a hose that had some cracks in it) but thought I fixed it because the symptoms never re-occured. Ha ha...

Hey guys, I don't post much here since I'm no mechanic, and there are so many more knowledgeable folks out there, but I had an experience today (and about 20 years ago) that I wanted to relate since I didn't see anything about it when I did a search. Problem: your carbureted 240Z cuts out / stalls suddenly when you're driving around, usually shortly after your fuel goes below 1/2 tank. Otherwise, at the beginning of your drive, it starts up just fine, seems to run fine. But get below 1/2 tank, and at some point it just cuts out, stalls, and refuses to re-start. Cranks over fine, but won't fire. You check the simple things. Spark and fuel. Spark looks ok. Check the fuel filter and if its dry, or basically empty, you may have a leak in one of your rubber fuel supply hoses. If you put in some fuel, a few gallons will do it, crank the car a bit to get the fuel up to the carbs, if you have this problem, the car will fire right up. Fix: replace your rubber fuel lines, usual culprit is the one going from the fuel tank to the metal line on the unibody. What is happening is that there are small cracks in the rubber fuel hose, they may be almost impossible to see unless you bend the hose around a bit. If they're suspect, just replace them. So, what happens is, when the fuel is above 1/2 tank, there is enough fuel pressure from the weight of the fuel itself to help the fuel pumps get the fuel through the lines, inspite of the hairline cracks. Once the tank goes below 1/2 tank, there is not enough downward pressure from the fuel in the tank to help keep the flow going, and you lose the pressure, no more fuel is being delivered to the carbs. The car cuts out, won't re-light. Put in your few gallons, crank a bit, it lights and drives fine. Ok, how do I know this? Well, today I took my new to me '70 240Z for a ride to a local Z car restoration shop to discuss some work with the shop owner. Its only the 3rd time I've driven the 240 since I bought it about 2 mths ago or so. I was planning on going over the car and replacing anything suspect like hoses, belts, fluids, etc, but just had surgery, didn't get to it, etc. Anyway, I really wanted to meet this Z car guy and have him look at my car so we could form a plan to fix it up. So I fired it up and drove over there. The car ran great and I was having a great time putting around in it. Heading home the car cut out suddenly, just stopped running. I pulled over and tried to re-start it. It was cranking fine, everything seemed fine, but it wouldn't fire. I got out, popped the hood, did a quick check, belts, hoses, spark plug wires, coil wires, anything I could see or touch. At all LOOKED ok, but I didn't have any tools so couldn't do much troubleshooting. Soooo, got back in the car and tried to start it again just for the heck of it. Thinking maybe it was an electrical component that was heated up and maybe it would cool down and I could get home (5 miles away). I know, wishful thinking. Ha ha. Anyway, as I was sitting there considering my options for calling for help, I studied the gauges again (with the ignition turned on) and noticed the fuel was just below 1/2 full. Bingo! Been there, done that! Years ago, when I owned a '72 240Z, it did the exact same thing. Started up, ran fine, fuel below 1/2 tank, cuts out, won't restart. I spent a lot of time trying to figure it out and finally traced it back to that dang rubber fuel hose between the tank and the metal fuel line. Replaced that on my '72 about 20 years ago, bingo, problem solved. Then of course replaced the rest of the rubber fuel line sections (and return hoses, vent hoses, etc while I was at it). So, with today's little mishap, I called the wife and had her bring down our little tool box, 5 gals of fuel, jumper cables (in case I ran the battery down), and some starter fluid. Put in about 3 gallons of fuel. Starter fluid. 1: to squirt in the airfilter housing to see if the car would try to light up. If it would, then chances are it was fuel related and not electrical. 2. A quick shot in the air filter after fueling the car up just to help it light up while the fuel is making its way from the tank to the carbs. Sure enough, after putting in the fuel and a shot of the starter fluid, it fired right up and I made it home no problem. Could see fuel in the little plastic filter (as opposed to dry when the car cut out). Even stopped at the bank, and it fired right up after and took me home. Soon I'll be doing what I should have done in the first place, which is going over the car front to back and replacing anything suspect, or anything likely to be suspect. Sooo, if your early Z is cutting out at 1/2 tank of fuel or less, and you're going insane trying to figure it out. Remember. Spark and fuel. If its fuel delivery related, check those rubber hoses. Ed ps: I'd be interested to hear if anyone else has ever experienced this. I can't be the only person to have experienced this with 2 different 240'z, especially 20 years after the first time! :eek:

Heh, heh. zpression. Excellent. I had it for years. I recently bought a '70 240Z, so I'm now in zcovery.

I was wondering the same thing.

I know, but I can dream can't I? Ha ha...

Thanks on the pics! I think I got an ok deal. The car looks much better in the pics then in person. It was advertized as a rust free Z, but lo and behold, its got the usual rust. But after getting the car up on a lift and checking it out, I was comfortable that it was worth the asking price, since my budget wasn't going to allow the purchase of a really nice, rust free Z. And the seller seemed like a decent guy, turns out we know a lot of the same folks in the local motorcycle scene. And the seller restores 70's motorcycles, and he's a 510 nut from way back, so he knew what he was talking about and didn't try to bs me. He was thinking of listing the car on ebay and I'm sure he could have gotten more for it, but he said he really wanted to sell it to a Z car nut that wouldn't run it into the ground and that would fix it up or restore it. My biggest concern is the rust on the rails, its pretty substantial. I was hoping to get away with some body work here and there, but the more I think about it, the more I think its going to need to be completely dissasembled and re-done. First order of business is to simply start listing all the things that I am aware that it needs right now. Then plan out the body work/paint work, then figure out when to do what, and of course how to budget for all this. I don't have the time, $, or energy for a concourse restoration, but I would like to get the body rust free, with a decent paint job on it. Then get the mechanicals right, then the interior. Then I'd like to find another Z for rallying! Ok, only kidding on that. Alright, half kidding. I really would like to find or build a rally version for our forest roads out here. And this is my first big car project, so it will be a long term project for me and I'm looking forward to it. And this site has already been a huge help. I may not have bought the car if sites like this one didn't exist since I'm not a mechanic or body guy. Anyway, rambling on here trying to answer a simple question, yeah I think I got an ok deal on the car. :^) Ed

I was waffling over whether to buy a Z or not for the longest time. The deal was, if I bought a Z car, I'd have to sell my street bike to pay for the Z. Being a life long motorcyclist, I've been going back and forth on this forever. Finally decided to buy the car (yesterday!) and now have to sell the Ducati. I'll see how long I can drag that out. Maybe my wife will forget about it and I'll get to keep it. Hence the name seemed to fit. -Ed

Thanks for the nice welcome guys! I live in Duvall, WA, USA, its about 30 miles east of Seattle (I just updated my sig). Hmm, so there's a cast of characters on this site too I see. Just like my dirtbike forums. Very cool. Yeah, I'll have to call myself something else since Ed seems to be already taken. Hmm. Maybe Duvall Ed, or Eddie Z, or...

Hey gang, Just wanted to say hi. Great site here. Been lurking and learning a TON! Just bought myself a 1970 240Z. #954. 174k miles. Drove it home today. I am very excited about this. I owned a beat up '72 240 while in college years ago, and have been wanting another ever since. We've also had a bought from new 260Z, and a used 280Z, in the family. Wow, can't believe I took the plunge. The Z is in pretty good shape. Pretty much stock and all there. Some rust on the rails below, and some rust here and there. Needs lots of freshening up, but I'm in no rush, so will get to things one at a time. Would like to strip the body down and get it dipped, or just stripped, but will figure that all out later. Right now just excited to have it. Will start the replace/repair list later. Did take it for a short spin down the twisties here after setting the tire pressue, and oh boy, it brought back memories. Car feels real good, but like any 30 year old car, will need lots of work and $ to tighten it up and insure a long healthy life for it, hopefully another 30 years at least. Added a few pics to the Photo Gallery section, but it looks like they're marked "image pending approval"? Well, looking forward to Z car ownership and spending time here learning and sharing. Ed