Date: Tue Jun 22 21:50:51 1993   
From: "lthompson@fisher.com" <lthompson@turtle.fisher.com>
Subject: Re: Need help starting '74 Z

Mikef may be onto something.  I had a fuel starvation problem on a '72 Z
with SU's.  On this car, replacing the fuel filter didn't help though. 
After disassembling the carbs, I found a mess wire screen filter badly
clogged on the input end of the both SU carb float chambers.

I believe the '74 flat top SU's may have the same mess wire screen filters.
On the '72 they are a cylinder screen installed around a bolt that holds 
the metal fuel input hose nipple.  I can't remember if you are running
stock carbs.  I somehow seriously doubt it...

Lee
lthompson@fisher.com


[I fought the same problem in my 75 Z.  The gas tanks for FI engines (and
maybe others as well) have a still well with small slots at the bottom
that is designed to keep good suction on the fuel pump even when
cornering.  Best I could tell from looking in the filler opening, there
is a screen around these slots.  Mine got clogged from 15 years' worth of
debris and rust.  I tried a bunch of things to remove the grunge
including high pressure washing and a professional flushing chemical.
What finally did the trick was a rust and scale remover called CLR,
available from Ace Hardware and probably K-mart.  It is basically a
phosphoric acid pickling mix with some detergent for good measure.  I
mixed a half and half mix, poured it in the tank and heated the mix with
a hot air gun close to boiling.  It dissolved the rust and loosened the
sand and crud.  I followed this up with a baking soda neutralizing bath
and an inside-out high pressure wash.  I have a high pressure washer so I
fabricated a nozzle I could maneuver from the filler inlet inside the
still-well and blast outward.

One warning: Gas vapors evolve from the metal and from the debris
despite any reasonable amount of cleaning.  Even after my acid
treatment, after the tank sat for a day, my explosive gas meter showed
the atmosphere in the tank to be at the lower limit of explosive.  Do
NOT get flame or sparks around the tank.  When I was working on my tank
I inerted the atmosphere with argon from my TIG welder.  If you have the
facilities, this is a good idea.  If you don't, a fan rigged to blow air
through the tank is advised.  JGD]

Date: Fri Jul 30 13:02:52 1993   
From: gla103@phys.anu.edu.au
Subject: Welding the fuel tank...

	A question on welding the tank on 240Z's. 

I have a leak in my petrol tank along the seam that joins the two halves
together... so, alas, it will have to be welded up. Has anyone else done
this, and if so how successful was it?
     Also are there some explicit tips on suitably venting the tank to avoid
an explosion? 

                               Thanks in advance

					Garry 
					gla103@phys.anu.edu

[Yes it is possible to weld gas tanks and I've done it.  It is impossible to
flush a tank sufficiently to supress explosive vapors.  Those who think they
can are the ones you read about in the paper.  In order to do it safely
you must inert the tank.  One way is to simply fill the tank with water
and have the area to be welded over an air bubble.  Another way is to 
purge the tank with nitrogen or argon.  More expensive but sometimes 
more convenient.  JGD]

Date: Fri Jul 30 16:37:48 1993   
From: rsiatl!emory!EBay.Sun.COM!Dennis.Loyer (Dennis Loyer)
Subject: Re: Welding the fuel tank...

> From z-car@Dixie.Com Fri Jul 30 10:08:29 1993
> To: z-car@dixie.com
> Subject: Welding the fuel tank...
> Content-Length: 875
> X-Lines: 22
> 
> 
> 	A question on welding the tank on 240Z's. 
> 
> I have a leak in my petrol tank along the seam that joins the two halves
> together... so, alas, it will have to be welded up. Has anyone else done
> this, and if so how successful was it?
>      Also are there some explicit tips on suitably venting the tank to avoid
> an explosion? 
> 
>                                Thanks in advance
> 
> 					Garry 
> 					gla103@phys.anu.edu
> 
> [Yes it is possible to weld gas tanks and I've done it.  It is impossible to
> flush a tank sufficiently to supress explosive vapors.  Those who think they
> can are the ones you read about in the paper.  In order to do it safely
> you must inert the tank.  One way is to simply fill the tank with water
> and have the area to be welded over an air bubble.  Another way is to 
> purge the tank with nitrogen or argon.  More expensive but sometimes 
> more convenient.  JGD]
> 
>

About two months ago, I had to have my tank welded also.  I hung arround the
shop to watch (from a distance of course) to see if I could pick up some tips.

The man who welded my tank stuffed dry ice down the filler neck until the fog
started to rise up out of the tank.  he stated that since the CO2 fog is
heavier, it displaces the gas fumes upwards.  By the time the fog comes back out
the filler neck it's supposed to have displaced all the fumes. As long as there
is no residual fuel left in the tank, this should take care of the fumes.  
However, I must repeat JGD's warning, and add one of my own,  if you're not
a truly expirienced welder, leave it to a pro.  My tank had a hole, and a crack,
the crack ran all the way across the bottom, and the hole was about the size
of a nickel.  It only cost me about $30.00 to have someone else do it.  Money
well spent when you figure in the risk involved, and that it's someone else
taking it and not you.

[Advice well taken.  I have to debate the dry ice trick just a bit.
While CO2 will inert the tank, the white smoke is condensed water vapor
caused by the cold and NOT an indication of CO2.  And unless you live
near a dry ice plant, it is much harder and more expensive to get than the
cylinder of Argon on your TIG/MIG welder.  Another option, lacking 
a TIG welder, is to use the CO2 from a beer keg tapper.  Easy to rent
at party supply places.  I'd MUCH rather just fill the tank with water
and be done with it.

One other note.  If you have to weld up a crack, that is a good indication
of stress.  The adjacent steel is probably suffering incipient cracking.
Anealing the area where the crack would run to by heating it red hot and
allowing it to cool slowly is a good idea.  JGD]

Date: Thu Oct 7 21:19:00 1993   
From: rsiatl!emory!pc.Trimble.COM!DBALINGI.SALES (DAVID BALINGIT)
Subject: fuel tanks

>turbo (2" SU suck-through system) to fuel injection.  Unfortunately, if
>the fuel tank is less than about one-third full, every time I go around a
>corner the fuel pump sucks in air and the engine leans out or even
>stalls.

Help me......

Is the 280Z tank baffled? It doesn't seem to be in mine. I have fuel 
starvation problems if my tank has less than about 3-4 gals.  This 
usually happens in long left hand turns. Keep in mind this is an IT race 
car so I'm cornering at greater then 1G. One solution is to install a 
good fuel cell (it's also a good safety idea).  Is there anything I can 
do to the stock tank? Is it possible that the pickup is mis-located?

-dave
david_balingit@trimble.com
IZCC#66



[My 75 does the same thing when there is only a gallon or two left.  
In fact, that is my "better get gas now" indication; when the engine 
stumbles in a turn.  The tank is baffled but the baffles have small 
openings at the bottom to allow gas to enter.  It also allows gas to 
exit.  The real problem is the amount of gas in motion at any time.
The fuel pump moves a LOT of fuel, most of which ends up dumping back
in the tank but NOT in the well.  During cornering the well
is fairly quickly pumped dry and the gas ends up against the walls
of the main tank.  Moving the return line discharge would be problematic
because if it discharged back into the well, the gas would rapidly 
get hot as the small quantity is repeatedly circulated to the engine
and back.  Only solution I know of is to keep the tank fuller :-)  JGD]