Intermittent Loss Of Power-1972 240Z Stock

[madkaw]

I guess you checked the sending unit to assure it was clear? 

As far as ignition, do you have a spare coil to try?

[siteunseen]

When you get the gauge, you may try a "T" fitting with a 3' or 4' section of fuel line to your driver's side wiper blade.  Zip-tie the gauge to it then go for a drive.  

 

EDIT: Have you blown out all the fuel lines?  If the tank has been cleaned the lines may not have been.  I don't know if it could cause your problem but there's a fuel vent line manifold below the coil.  4 rubber hoses, one from the tank for venting, two to the air cleaner housing and one more to the PCV tube below the front carb.  Just some thoughts. 

Edited April 17, 2015 by siteunseen

[bartsscooterservice]

You could drain the tank with the bolt, and use an inspection camera with light and look into the tank ( to the bottom ) from the filler neck, easiest way to see if there is junk in there, before you remove the tank completely. Maybe it's not necessary

[AWAUDIO]

@barts  I wish I had one of those!  As the tank drained dry without any debris, I'm going to try blowing out the lines

@siteunseen  I'm waiting for the Amazon gauge with 3/8"  "T" fitting and using hose clamps.  My best friend lost his Z when a fuel line ruptured onto his exhaust manifold, and damn if that engine didn't keep running, pumping gas, until it was a total fireball

@madkaw  As a matter of fact, I do have a spare. And it's easy. I thought I had this pegged as a fuel issue, but pending fuel line cleaning, the possibility of a collapsing  coil was at the back of my mind, especially when it occurred under "hot sink" conditions. By sending unit, do you mean fuel pump?  Standard clear fuel filter was changed twice (does only fill 2/3 full…..???)

if there is another sending unit, let me know.  FSM just shows a million vent hoses,  main fuel outlet fitting, and fuel float assembly.  

 

Thanks again for bearing with me.  Was good to see clean fuel.  I had thought about running the engine from a 5 gallon can, by passing the fuel lines & tank and going first into the filter and then around it direct to fuel pump.  But I really want to avoid running the engine where there is a possibly of major FUBAR.  If I can make it safe, I may try that while waiting for my fuel pressure gauge.  Here's one more thought, I just remembered I had a similar problem with my 1948 Plymouth years ago.  Turned out to be my gas cap was vacuum sealing the tank, and removing the gas cap made it run perfectly.  Replacing gas cap was the solution.  I wonder?

 

Thank you all again for bearing with me,   Andy

[siteunseen]

I think Madkaw is saying you can remove the fuel gauge sending unit in the tank and snap some pictures.

 

See the crud line on my old one.

[Stanley]

Easy to check relative gas height in bowls with straw from can of carb cleaner. When it's running good, pull hoses off vents and put straw down the vent. It will rest lightly on top of the float. Mark it at the vent fitting. Then do the other one. Then, when you're driving and it starts sputtering, put it  in neutral, shut it off and coast to side of the road. Check them again. If one is down, and the fuel pressure is OK, might be a problem with that float or valve.

 

A point on a float can touch the side of a bowl, restricting it's movement. Maybe hitting a bump could stick or unstick it. If so, a light touch with sandpaper on the side of the float will fix it. Doubt if that's it but it's possible.

[siteunseen]

I messed up! The vent from the tank is the middle backside. One top hose goes to air filter housing, bottom hose goes to pcv tube. Sorry for the late EDIT

[AWAUDIO]

@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?

Edited April 17, 2015 by AWAUDIO

[siteunseen]

Yes, I believes your coil could be a quart low. Smiley face.

Get one of those smart kids with good eyes to click MORE REPLY OPTIONS at the bottom of your post.

Then CHOOSE FILE

Then ATTACH FILE

[AWAUDIO]

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

[bartsscooterservice]

If the tank drained without any debris coming out, I wouldn't think that's the problem. Like some suggest you could also see some of the inside of the tank when you remove the fuel sending unit.

 

You could try another coil. You have to make sure the distributor rotor has no play, and the lobes are greased with the right grease for points, are else they will wear out pretty quick.

[siteunseen]

Damn!  What a beautiful car.  More pictures are needed to try and figure out your problem.