One-Family 1972 240Z Restoration (HLS30-93069)

[BoldUlysses]

I drove it around the neighborhood a little yesterday evening, and I pretty much have it eating out of my hand now.

The front carb's piston is a little sticky, as is the rear carb's choke. Once I clear those up, it should be 100% driveable.

It's much quieter now at idle since I replaced the air injection plugs.  I'm sure the brass plugs were leaking.

A wiring connector to the combo switch at the steering column worked its way loose, so I have to tap the plastic shroud on the column to get the headlights to come on.  Need to reseat that.

Also, I finally installed this OEM underhood inspection light I found on a junkyard Z about 10 years ago.  The plastic lens from the junkyard was cracked and yellow, but fortunately ZCarDepot sells replacement lenses and even LED bulbs.  I don't think our Z ever had the light, since it's in the area where everything was removed/relocated to make room for the A/C compressor.

There's a strong gas smell in the garage now.  No leaks of any kind, but I wonder if the PCV valve I bought might be faulty?  Need to investigate that and the evap system.

[BoldUlysses]

Spoke too soon, obviously.

The fuel tank sprung a leak, which I traced to the o-ring on the fuel level sending unit port.  The grommet for one of the electrical posts might be leaking also, so I just ordered a new o-ring, lock ring and sending unit.

I checked out the evap system too just to make sure I had it connected properly and the tank wasn't getting pressurized or anything.

I've got a nice steady 700 rpm idle at 20° BTDC.  Car runs OK at low/moderate speeds, but wants to either run on 1 carb or die completely in high-load situations.  This got me stranded on a local road earlier today.  Fortunately I was able to get it to catch again after a few minutes of intermittent cranking, and I was only a few hundred feet from my neighborhood entrance, so I was able to nurse it back home.

Very frustrating.  Suspect fuel supply issue, so I'm going to rebuild the pump and replace the filter.  Sigh.

[BoldUlysses]

Rebuilt the OEM fuel pump earlier this afternoon.  I had the dinky-looking aftermarket piece on there, so it was nice to get this one back on the engine.

Still waiting on the filter.  I ordered an inline fuel pressure gauge too to help me suss out the issue.  Going to blow the lines out with compressed air also.  Really hoping it's not the screen in the tank.

[inline6]

Sediment in the tank, if present, can plug the fuel supply pipe in the tank.  Check your filter (you may want to run clear ones) to see if bits of dark matter are collecting there.  If it stalls, and has you stranded... and you can undo the supply line just below the fuel filter, and blow back through the line into the tank... and then assemble and fire it up and drive away, then you know.  Many years ago, I had that issue.   Had to drain the tank and get it coated inside to stop rust flakes from clogging the line.

Edited August 7, 2022 by inline6

[BoldUlysses]

Is there a sock/screen on the inlet to the fuel supply line in the tank?  I actually cleaned and resealed the tank with the POR-15 kit about 10 years ago:

https://por15.com/collections/fuel-tank-restoration/products/fuel-tank-repair-kit

I made sure both the supply and return lines were clear at all points in the process, but I'm worried now that like 90% of the sock/screen got coated anyway.

I have a clear filter already, and I do see some dark flecks in the bottom.  Hmm.

The good news is that this a relatively recent issue.  If the screen/sock had been clogged from Day 1, it would manifested itself a long time ago.  I just don't want to have to replace the tank...

 

Edited August 8, 2022 by BoldUlysses

[inline6]

My tank did not have any kind of screen or sock at the pipe (inside the tank).  When I bought my original 240z in 1992, the previous owner told me to "change the filter often".  I was 22 - didn't know much.  So, what I described above was happening.  Car would drive fine, especially if the tank was full.  Then, when the gas level would go down, the debris would find its way to the supply pipe opening.  The car would empty the SU fuel bowls and come to a stop.  The first few times, I found that, after a few hours, it would start up again and run fine.  One of the subsequent times it did it, I had my tools.  I disconnect the hose at the fuel filter inlet, stuck my head in the engine carpartment and blew back through the pipe as best I could.  Got gas in my mouth in the process.  😖  But, it started when the hose was reconnected.  

I dropped the tank, and used an Eastwood kit to acid wash and seal it after that.  All kinds of rust flakes in that tank when I took it out.  

If you have an obstruction, when it does it again, you could check to see if the fuel bowls are empty.  With a rebuilt pump, running empty in the bowls intermittently would point me in the direction of an obstruction in the tank.  It may just be a few chunks - not necessarily the tank needing to be replaced.

[inline6]

Happened upon a picture of the tube in the tank with no screen) in this live auction on Bring a Trailer - pic #315:

https://bringatrailer.com/listing/1970-datsun-240z-86/

[BoldUlysses]

Wow; great insight, sleuthing and tips!  I searched high and low for a pic of the inside of the tank; nice find!  Such a relief that it doesn't have screen on the end.

And my symptoms sound very similar to yours:  Seems to run better with more fuel in the tank.  I think the added gravity of the extra fuel supplies a little extra pressure, and also dilutes the contaminants in the tank.

Filter is on the way, and EVERYTHING is getting checked and blown out this weekend.  I've seen folks run an extra inline filter back near the rear axle; I may do the same.  Wish me luck, and thanks again!

[BoldUlysses]

So the forum software won't let me edit the first post in the thread (where I wanted to place this image), but I figured I should share anyway.  My mom found this a couple of months ago.  My parents driving away from their wedding in the Z, May 1974.  They'd had the car for about a year and a half at that point:

[BoldUlysses]

So I think I may have it sorted out.  Don't want to speak too soon though...

 

I installed an extra fuel filter inline next to the tank. 

 

 

I also installed a new primary fuel filter and the new fuel sender unit, o-ring and lock ring.  I had to re-solder one of the connectors and use the heat gun on the rubber boots to get them soft enough to push over the terminals.  I also blew out all the fuel lines with my air compressor turned down to 40-50 psi or so.

 

Started the car after a bit of cranking to fill the filters, and it seemed to run...OK.  Still missing and hunting somewhat, but I got it into a state where I could drive it around the neighborhood.  After some more tinkering, it was alright, but then it died again the way it did last week.  I coasted into the driveway and pulled the top off the rear carb fuel bowl:  Dry as a bone. 😡

 

Really frustrating, but then I noticed that I forgot to put a hose clamp on the fuel pump inlet line.  Also, it was kind of loose.  I wonder if the fuel pump had been sucking air, creating a kind of vapor lock condition in the fuel lines?  Regardless, I put a clamp on it, and the car seemed to run a lot better.  I was able to drive it down the road a little ways and it didn't threaten to die at any time.

 

I didn't want to get greedy so I came home and decided to wash it.  It's the first bath it's had in almost 20 years.  The paint cleaned up really well and looks fantastic; the painters did a great job with it.  There are a couple of tiny water leaks but nothing major.  I don't plan to drive it in the rain anyway.

 

 

 

 

 

 

Current engine bay status:

 

 

Yes, that's blue painter's tape protecting the left shock tower from getting scratched by the air filter wingnut.

[BoldUlysses]

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

[SteveJ]

When it dies, does it happen gradually or suddenly?