Intermittent Loss Of Power-1972 240Z Stock

[AWAUDIO]

    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

   

[madkaw]

If that line was gummy, I would bet that's your issue. This has been discussed here before so there might be some suggestions in the archives

[AWAUDIO]

@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

[gundee]

      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.

 

 

 

   

 

Call Bruce at Z Therapy. He should have some good ones that work well.

Edited April 24, 2015 by lumens

[bartsscooterservice]

You can use rubber gasoline line they use for lawnmowers, scooters etc, works fine for the bowl to carb connection.

[Mark Maras]

AWAUDIO

 Although I don't know the why, the fuel line holders on my 71 were also squeezed together just enough that they were non-removable from the lines.

[rossiz]

+1 on ztherapy - they have a specific high-silicone hose for this application, which will hold its shape and not put stress on the nozzles.

[AWAUDIO]

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

[Bonzi Lon]

I did not lube the O-ring when I installed my new sender unit, that was 8 years ago.

 

Bonzi Lon

[AWAUDIO]

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!  

Edited April 27, 2015 by AWAUDIO

[240260280z]

I read in a Datsun book that it was common for 240z owners in hot regions to carry a thermos of ice water to pour on the mechanical  fuel pump when heat soak set in following a stop. Not sure how accurate this was but another piece of data.

Edited April 28, 2015 by Blue

[gundee]

You don't by chance have one of these 73, 74 rear fuel pumps on your 72 like I do.