AWAUDIO

Ok folks, latest update. Car on jackstands. Removed fuel sender unit (those electrical connections are from hell). Using inspection scope from top, the bottom of my tank and inlet tube is clean, clear, nada. At the elbow, with scope from top, I still think I see corrosion and a hole in the bend, as the pick up tube heads downward. Let me state at this point that those scopes are great if you're not lying on your back trying to manipulate a flex camera into odd places at odd angles while looking at a 3" screen with high contrast. Now you know why proctologists get the big bucks. I am trying to find a fiber light optic source to feed into the tube so that I can see if I see light in the tube while looking at it from inside with the scope. I really want to verify I have a hole before dropping tank. I'm 90% sure the corrosion I see is enuf, but my time is free, a new tank is not. I'd love to post pics, but there is no way I can manipulate scope and take a screen shot. I could video it, but that means a feed to the studio……..ugh. So, it's Edmund Scientific for a fiber optic source (which won't spark) but is bright enuf to see thru a hole in the tube. Any other thoughts? I'm at the end of the line…literally. Aw

My next step is doing the jackstands ( I hate doing that) (it's a PIA and I'm getting too old to crawl under a chassis) be that as it may, after it's floating I'm gonna run it off external fuel and watch for bubbles in fuel filter. I'm sure it's gonna be good. Then I'm going to run it off the feed line from the tank (in case I have a solid fuel line failure somewhere). Then it's drop the tank. To those of you out there who fight these problems like I have, hang in there, this would have been a financial nightmare in a shop….nothing against shop guys, it's just that it's taken 2 months (part time) for me to get it down to a probable problem INSIDE the tank. If there are any gurus out there who could have sent me straight sooner…….I'd have paid for it. To date It's been 2 months of: new plugs. points (twice), condenser, dizzy cap, interior dizzy wires (long and short), insulator, rotor (x2), dizzy wiring external (all new crimps) , dizzy connections to coil, new coil, coil wires, carb filters (internal-small ones), carb float to bowl hoses (Z Therapy), Carb float gaskets, fuel filter x 2, fuel pressure gauge on manifold, fuel pump (mine is perfect at 3.5 lbs) replacement at 5 lbs. (and I have full OEM rebuild kit from Canada), So this has become a career. If I didn't have to work for a living I coulda maybe nailed this sooner….NOT. I still don't have this resolved. But I'm getting closer. If I didn't have work to distract me………..

ZCarSource has them for $315 plus core (old tank) Jeez, my tank looks good inside……... http://www.zcarsource.com/gas-tank-240z-70-73-reconditioned-de_8_55265_52737.html

BTW If I verify internal tank pick up tube problem, does this mean a new tank? Can you separate and repair tank? This is uncharted territory for me. I actually bought ALL the tank replacement hoses 3 years ago, just because I thought it was a good idea and they were available. Yes, the OEM ones. Wasn't so expensive back then. But now it seems like cheap insurance. So what are my tank options? I've already started looking for replacements, but repair would be nice. aw

OK sports fans, the results are in….I think. After replacing fuel pump, and noticing that there were air bubbles coming out of the top of the fuel filter, I thought it had to be the line into the tank. WRONG That main line was fine, vent line was fine, no leakage at the rear tank float (it looked perfect) no wetness anywhere. OK, drain the tank again. A word of caution and advice. You will get gas on you, it will be messy, and please be safe. Tank drained, and out came my Harbor Freight inspection scope. At this point I will issue a disclaimer. As I was using this scope inside my gas tank, and talking to my brother at the same time, (who also has a 240Z) and who is a certified moon suit safety engineer, he inquired: "Is that device you're using certified to work in explosive environments?" DUH Well guess not…….Ok I'm still here, but that is not an endorsement. Those fumes in the tank can and will explode if exposed to a stray spark. So, fool that I am, I'm practicing being a proctologist in my gas tank, trying to decipher the imaging, and after about an hour I get it. My fuel float is perfect, I can read the info on the side, the tank looks clean, rusts spots here and there, no particles drained. Top, bottom, sides, all look ok. I mean, rust spots, nothing looking scary. Eventually I stumble on the fuel inlet tube which enters high next to the vent line and goes toward the bottom of the tank. I couldn't examine the bottom of the tank, as I was using the drain outlet for my inspection insert. So, I bumbled along until I could examine the fuel intake tube inside the tank. Not as easy as it sounds. I spent 2 hours listening to good music while I manipulated the probe end. Finally I got a view of the tube. I wasn't sure I was certain of what I was seeing, but after multiple pulls and retries, I was pretty sure I found the problem. My fuel pick tube inside the tank has a hole in it. When the fuel tank is super full it runs great. When the fuel level drops below the hole, the engine starts sucking air. If the tank is super pressurized, on a hot day, pickup isn't a big problem. The time it happened cold, it was a cold morning. Got hot outside later in the day, pressure in tank builds, not so much a problem. Full tank, super full, it was never a problem. I think the hole in the line has gotten larger and the problem has gotten worse. It was a gradual failure. I never correlated fuel tank fullness till now. On the scope, I could only ID the "apparent" hole once. It's impossible to snap a pic while probing. Will hook up video recorder next. And I'll run motor on jacksatands off external fuel supply. I'm going to return my original pump to service, as it's beautiful and rebuilt. But, first, double verify hole in fuel pick up tube in tank. No easy way to pressure test it. I just have to be sure using scope. Any and all thoughts accepted and appreciated! Thanks for staying with me, it's been a long haul……... Andy

Ok folks, getting there inch by inch. Put in a new fuel pump from MSA. My old one looked way better, but new one did put out higher numbers on the in line gauge. BUT guess what, problem remains, so I have it isolated to a pick up problem in the lines to the tank, from the tank. That inspection scope is gonna pay for itself. It's on to the jackstands and into the tank………..again. It's gotta be there. I have no where else to go.

@AZ-240Z I have that insulator on order and am awaiting delivery! Will replace as soon as I get it. Along with the correct interior dizzy wires…the long one and the short one. @siteunseen I've done the clunk test and they seem to be ok, and unless I have a bad fuel pressure gauge, I'm hitting fuel delivery issues first @Zed Head Unless my fuel pressure gauge is off (I hate it when test gear goes bad) I'm going into the tank and lines and fuel pump. When it fails big time, it's a lurching drive from hell. When it's just throwing a hissy fit, it'll bobble on hard acceleration, this past Cars and Coffee, was the "I'm just gonna let you know I'm not happy". And the time it was a lurching spasm from hell it started running fine 2 blocks from home. Her name is not Christine, Steven King notwithstanding, it was a clear a case of possession as I've seen since the "Exorcist". I have to ask all your indulgence, I'm freelance and the phones been ringing, and I didn't get a chance to use my new inspection scope today. So she's not on jackstands yet, but my fuel pump parts are on the the way from Canada, a new cheap fuel pump and gaskets are on the way from MSA, and the dizzy insulator and wires are also in the mail and on the way. When I'm done, I think I'll have a few spare parts to let go. Thank you all again for your thoughts, I won't be able to work on her again till this weekend. Andy

@blue I'm going there after this adventure is resolved. The posts I've seen and researched have pointed out a tach issue. Have enuf problems at the moment to not add another. But did see the thread where the tach needed to be disconnected to make it work. I'm sure this been done to death on this site. Back to my own hell……... Aw

@lumens The volume per the FSM is 3.71 quarts @1k rpm per minute. As I could imagine a "T" hose setup, which would let me run raw fuel out of a running engine into a containment vessel, this would satisfy the test, but I'm not the gut to try this. I maybe crazy, but not insane. I'm sticking with the fuel pressure issue (I really hope my $25 gauge is good). Volume, as in mixing music, can sometimes be deceptive. As it's getting dark in NorCal I won't get her up today. But the inspection scope I got actually looks useful. It focuses very close and the screen is sharp. Has a variable light source and a right angle lens adapter with a 36" head lead. Is waterproof to 3 meters, do not use in gas or solvents. On a really weird tangent, one of the other guys inquiring to buy the fuel pump on EBay lives 3 minutes away. I thought I knew all the "Z" cars in 94947, but I guess not. Considering the world is a big place, that's just plain weird.

Hello All, thanks for staying with me. I have a day off, so I'm putting her on the stands and checking the tank. First I'm going to Harbor Freight for an inspection camera ($79) and looking into the tank. Also checking flex fuel line from the tank. In the meantime I've ordered the fuel pump rebuild kit from Canada and downloaded the excellent rebuild procedure from WoodWorkerB http://woodworkerb.com/home/datsun-240z-rebuild/datsun-240z-mechanical-fuel-pump-rebuild/ as a number of folks have told me the fuel pump could behave erratically. I'm also trying to buy an NOS fuel pump off Ebay (spares are gold in my book), but seller is "out of town" -first time I've seen that on EBay with a "Buy It Now". Please don't ace me out if you need one. As a third backup, I've got the gaskets coming from MSA with a cheap non factory OEM pump on the way. So attacking the fuel lines and tank will be first task. Will access tank thru sender unit as I have nut and "O" ring. Took it to Cars and Coffee this weekend, and as usual she started, ran and pulled fine, got there, sat, started fine, and then started acting up on the way home. At least she's predictable. Fuel pressure was again low when I got home. If I didn't have work get in the way, I could solve this and end the suspense. @lumens I know that there are 3 ball bearings in there and that if you have 2 in there you're lucky. If it didn't just scream when normal, I'd be all over that solution (along with a Petronix pointless system), but with my pressure gauge between pump and manifold, I think I'll pursue fuel pressure issues first. Thanks for the thought.

@Stanley I agree, those new pumps look cheesy. Used to be able to get pump rebuild kits. NOS pumps are around $350 ouch I don't think pumps go intermittent. Someone correct me if I'm wrong. I checked screws on mine, all fine. Couldn't detect air leak at the pump gaskets, thought of that. @siteunseen Will have to wait till this weekend, and I will be careful. If I didn't have to work for a living, working on the car would be a lot easier. BTW, started it up a few hours later and fuel pressure was back to normal. At least I have something to go by now. I was actually pleased to see the low fuel pressure reading. I now have a target to attack. Will report back in a few days. Thanks to all for the suggestions. Andy

No rear fuel pumps. BUT Just fired it up after 3 hours of sitting, and she screamed. Purrfect. Fuel pressure back to 3.5 lbs. Mounting full blown attack on the tank and connections. Am still planning on 5 gallon ext supply test. Really need a scope for tank, wish one of the maker folks had one I could make. AW

Round 4 page 4! OK! Finally I have something to go on! Replaced the bowl to carb lines (mine actually in examining closely looked ok, and Z Therapy can't send new ones til next week). Had everything open to bare carbs and checked everything I could see. No leaks, all looked good. Engine fired right up, even after draining float bowls. It fired, coughed once and started purring. Fuel pressure at 3.5 lbs. Off for a drive. 15 minutes running and pulling perfectly. Turned off and put 5 gallons fuel in, had 1/4 tank or less in there after draining. Started home and bingo, missing under acceleration, not lurching but not happy. For yucks, pulled gas cap. Still missing under acceleration. Got home, without turning off, popped the hood and low and behold fuel pressure gauge at rear carb was reading 2 lbs. Accelerating (smooth under no load) still never got back to 3.5. Alrighty then. One last test before jackstands. I'm going to drain 5 gallons off tank and try running from fuel filter to gas can and see what happens. This will take the tank & lines out of the equation and I can go back and forth to see if fuel pressure varies with source. I don't think the other tank vacuum lines would make any difference to the test. "O" ring arrived for sender, so it's jack stands after quick test. Also, I noticed what looked like air bubbles in fuel coming from the top of the fuel filter to the fuel pump. I really hope my fuel pressure gauge is good, I'll know soon enuf. This is turning into a Saturday morning serial, all I need is Professor Zarkov and Flash Gordon to chime in!

Hello All, I have a call into Bruce. Bought his video when I got my car. I love his policy of offering to talk you thru any problems. I was told he did my carbs before I got the car. If tank ring shows up before new fuel lines it's up on jackstands. I was wondering if you're supposed to lubricate the "O" ring on the sender unit when installing? You do that with swimming pool lines. Will keep you posted. AW

@madkaw I specifically went the OEM route and those 2 - 6" lines were $22 a pop. Just couldn't believe they would fail so quick, which is why I didn't look there earlier. Wlll check archives for alternatives. I still couldn't believe my eyes when I was in there today and saw those lines looking funky. BTW, when installing the banjo bolts, the lock nut assembly went fine, and the fork shaped unit which is attached to the 2 float screws, went on fine, but mine had been bent/squeezed around the fuel line. I can't image why. Am I missing something? Seems like double redundancy to prevent fuel line from moving? Odd. Still going to work the tank and sender, thanks for sticking with me. AW

Ok, here we are, round 3. Pulled carb banjo bolts and screens. Pics enclosed. Very clean filter and only a few of the tiniest bit of somethings. Was chalky with a film, bit all passages and filter clean. Ordered 2 new filters ($2@) just to have. But, I did notice that the fuel lines I replaced 3 years ago, the bowl to carb lines, my rear one was wet and gummy to the touch. This could easily collapse when it gets warm. Tried ordering new set of lines from MSA and it's a no go. Factory OEM no longer available. Any suggestions? From what I understand this is the critical line for flexibility and durability. Too stiff and chokes don't work, too thin or cheap line and we have engine fire waiting to happen. Chime in on what you use. @AZ-240Z I opened dizzy and triple checked the insulators and the 2 wires inside the dizzy. I replaced one wire (from points to insulator on the inside) a few years ago, as the original was frayed. The 2nd wire from dizzy ground to plate measures good continuity .01 ohm. Can't see any cracks, but I may just order the insulator if available. @lumens no tach issues @bart I'm going up on jackstands this weekend to double check sender unit (if O ring and nut arrive) and I'm just going to put in a new rubber fuel line and check all the vacuum hoses at the tank. As for checking dizzy, I'd love to find someone with one of those old Sun analyzers. Remember those units? Thanks again for all the comments. AW

Once again, thanks to everyone. I replaced the hoses from the bowls to carbs with factory OEM hoses 3 years ago. Will check again. Will inspect dizzy for the cracked insulator. I had a loose connection there once, and it was the screw holding the condenser and the terminal you describe. I also crimped on a new connector (cheap insurance). Then it's float bowl and screens. Then it's up on jack stands for sender unit and flex hose to tank inspection. I like the collapsing hose idea. Will report back before she goes on the jack stands. AW

@blue Without a dyno, what I'm trying to think of is, what would cause engine stumble (not misfire or backfire), hesitation, and loss of power, under a load (running under power on the road) versus static revving? I'm willing to start from scratch. It's the load/no load that has me thinking. What engine systems fail under load, rather that at rest (running in driveway)? Will do the 3 steps I outlined above, but I'm thinking outside the box here. Thanks, Andy

@blue I'll put her on jack stands and hit the sender unit (once I get a gasket). I really wanted to find debris, but didn't on the drain or in the lines. I'll see if I can beg, borrow, or steal an inspection scope for the tank. BUT…what did you trouble shoot on the distributor you mentioned? It's the intermittent aspect that has me stumped. Did you have a dizzy with attitude? What did you find?

@madkaw I didn't remote mount the fuel gauge. In driveway, in it's stumble mode/ engine revs fine and fuel gauge at rear carb reads sold 3.5 . It's only under load on the road, after running for about 20 minutes, that she starts acting up (except for the one time she did it cold). I'm just reluctant to remote the gauge to the windshield, though I may have to. Thanks for sticking with me. AW

Ok guys, in the words of Sgt. Mac Elliott in the movie "Predator" "We hit nothing"…………. To date I've done the following: 1. New plugs , points, condenser, rotor, cap 2. New coil with all new crimped connections at coil, dizzy, resistor 3. Drained fuel tank, new fuel filter ALL lines checked and tightened 4, Checked lines from filter to tank New lines 5 years ago 5. Fuel pressure gauge installed at rear carb = 3.5lbs (bounces at idle) otherwise solid stable 6. verified voltage regulator into resistor 13.2v at idle resistor out 10.2 v into coil + 9.56 at coil - 6 v Starts fine, idles fine, runs great for 20 minutes or so, no over heating, pulls great, then goes into stumble & lurch mode. Will not miss or stumble except under load or hard acceleration. It will also go into total lurch limp home mode only to clear itself and start running fine. My next thoughts are: 1. per @blue fuel lines coming off carbs for check 2. per @madkaw go back to fuel tank for sender unit 3. per FSM check fuel pump output Ok, what else? It's either electrical or fuel. DOH And it's running in driveway, with no load has her purring. So what could cause an intermittent (some days screams fine, some days not so fine), not a constant intermittent? Temperature not a factor, NorCal.

Ok, I've had my 18 month old Grandchild for the last three days. Anything you want to know about diaper changing, Sesame Street, or nap schedules, I'm your guy. Working on Z tomorrow. Andy

@blue Problem is she doesn't die. Never has. Always lets me limp home bucking and lurching. Sitting in the driveway she idles perfectly and will even accelerate, with a slight hiccup, but she runs. Under load has no power. And as I mentioned, yesterday she just started like she wanted to go go go (usually I have to encourage her till she's warmed up). But I mean she was just screaming with lottsa power. When I last shut her off she was as described above. So I have a new coil arriving in a few hours and a fuel pressure gauge coming Sunday (I still can't figure out how Amazon can ship for free and deliver a $30 item on a Sunday). So I'll put in the new coil, install pressure gauge and run her until she has her hissy fit. Two things I did notice when she ran yesterday: one, the coil got very hot to the touch and the dropping resistor got too hot to touch. But again she was running fine. As for tank debris, I was so hoping it was something like that. But after draining the tank dry, into a funnel with a mesh screen, I found zero debris. I refiltered thru a second finer mesh into another gas can and found zero debris. My tank had fresh washer on drain plug, and appears as if it was dropped before I got it. What I didn't do (doh) was check the fitting into the tank from the flex hose which attaches to the solid line. I blew from the fuel filter fitting thru to flex hose disconnected from tank. So I'll go back there if I have to. Sometimes you just forget the obvious. Since I might be back there, I'll pull the sending unit, but first I have to order the gasket, so that will be #3 on the "To try list" BTW I have all new solid fuel lines. @siteunseen Thanks for the compliments, I have put a lot of effort into keeping her straight. I had to special order the cam lube for the points, the parts kid didn't even know what it was. So, yep, cam lube good, and I'll throw a new rotor on, I have spare parts and it's easy. PS here is engine right side Thanks to everyone for keeping with me, all the best, Andy

Ok, So it's on to coil. Am not abandoning fuel pressure till I get gauge from Amazon on Sunday (go figure, Sunday delivery for a $30 part). But the heat of the coil and it's age could be doing it. Will replace on Saturday with a cheap Napa one (don't want to use the spare I have, as it's for the Jeep) Will then run until I'm sure it's ok. I figure a full tank of gas will resolve fuel and electrical. Good excuse for a road trip. I have AAA free towing. Everyone else, don't stop reading this as I'm not out of the woods. Always looking for the next suggestion, especially if this has happened to you. Ran great today, but let's see what happens tomorrow. Thanks for helping. Andy PS my engine compartment

@siteunseen no problemo I'm going to post some engine bay shots, as this girls is wearing mostly new hoses and all new fuel and brake lines. As I said engine & carbs were rebuilt 5k ago. So, lines to tank from filter blown out and A OK. Fuel filter crystal clear. So I figure, what the heck start her up. She has always been tough to get out of bed in the morning. Usually takes lots of choke and manual foot to idle to get her to warm up and then she's perfect. (no don't there re girlfriends). So today, after emptying tank and lines to filter, I touch the key and she fires right up. Choke off, idles perfectly with no help from me and warms right up. Then she does what she does best, and runs perfectly. I mean, screaming fine, accelerating, no stumble, I mean purrfect. So I let her sit and idle for 20 minutes. Still perfect. Engine temps normal. So I bring out the voltmeter, the good Fluke. I notice the coil is very hot and the dropping resistor too hot to touch. Measurements as follows @ 750 rpm; into resistor 13.3v out of resistor 10.3v into coil 9.53v out of coil 6.56v So, in lieu of getting fuel pressure gauge, I'm going to put in an coil once I verify its a 1 ohm coil. Somebody correct me here if I'm wrong. I know the 3 ohm Flamethrowers are a no go with the resistor. I think madkaw might have put me back to electrical. My schematics don't show the cap value coming from the coil to the chassis or maybe I'm missing it. That could also be an issue. So, until I can measure fuel pressures, I'm playing with electrical. BTW, my fuel pump, looks in no way like the replacements they sell. @siteunseen thanks agin for the pics, I checked my hoses and all good. Andy PS I have 3 computers, 2 smart kids, and how do you post a pic here?