This steps are  for , working the fuel pump,filter, fuel pump regulator, pulling gas tank or lines, or pulling engine , pulling injectors or fuel RAIL.
DE-PRESSURIZE  THE FUEL LINES !  and all other warnings , regardless if engine runs or not!!!
Gasoline is very flammable, please take every precaution.
Rule 1:
The tank is pressurized and so are the fuel lines,  running  and not running ! UP TO 60 PSI (pounds!)
Ask for professional help, if unsure or confused, about this system! (it can be tricky)
If system is already leaking , do not run car and see if gas cap put ON, helps or makes the leak worse?
Most cars will slow the leak with gas cap on , but if the gas warms, or is warming, the leak will get worse.
Park any leaking cars at the curb, not near any valuable property, and DRAIN THE TANK NOW!
NEVER DO !:  
  1. Failure to take gas cap off first, before breaching the system. ( hot gas expands and WILL FLOOD your work space.)
  2. Allow Drained fuel in a garage or shop areas, or  very near you home or loved ones and possessions.
  3. Fail to drain gas tank to 1/2 way (remove 5 gallons , at least, if doing major work)  
  4.  NOTE:"gravity effects and accidental siphoning are bad, as are  weather warming trends."
  5. Never walk away with system lines open , buy the parts first, swap parts and close up fast.
  6. Never fail to get car level .
  7. Never allow gravity / vehicle angles or siphoning, to drain the gas tank, by any means.
  8. Never fail to use line stoppers or plugs,caps on the lines, when you take them off, buy them FIRST.
  9. Never fail to have 2 fire extinguisher near by, (one can fail) and 3 to 5 steps away from engine bay.
  10. No smokers in the area, or fuel fired water heaters or any other heat sources.  
  11. Do the work when daft neighbors, that smoke, or drift about un-announced, with a stoggy in the mug.
  12. What I do to avoid #12 above , I work fuel at home, when they are at work !! Kids in SCHOOL!
  13. Static Electricity and gas, are not friends.  Please take all precautions, in that regard.
  14. No plastic clothing, or creepers.  Touch the body of car first, then touch fuel parts second.
  15. Have a friend attend you with an extinguisher.  Fuel rated.
  16. Have a bucket (or small coffee can) so you can catch the dripping fuel < there will be ,no matter.

Do not allow someone (anyone) to have keys to this car , allowing them  unwittingly,to try to start a car with a open fuel system.!  ( do that, by pulling the battery negative lead when done de-pressurizing).
Use fuel proof gloves, fuel is toxic (Google ;Benzene toxicity)
If engine is dead,  use rags to catch fuel , take the rags far from home .  (hang them down wind from a tree?)
The fuel will spurt and hit your eyes, wear GOGGLES  PLEASE!

 If engine is dead?, read all rules above, first and my dead motor method below.
NO OPEN Flames or any heaters allowed near car.
Avoid confined spaces, by any means ! Delay,  find a safer place to work , ask for help.

If possible:
Work out doors,  call your insurance company and activate full coverage  now. and full life insurance.  No kidding.
Gas fumes are toxic and very very flammable.
Have a plan in you mind, before a flame starts (all it takes is spark , from metal to metal tools)  I even keep a blanket near by, and never water.
THE FAST way to bleed off pressure, on all SIDEKICKS and TRACKERs is :
  1. GAS CAP OFF.
  2. Remove the (left) rear tail light assembly 2 screws,  and pull that large connector  "See PINK WIRE"with engine running.
  3. The engine will die in 1min. slowly.  There will still be a tiny bet of pressure, due to injectors die and stall motor, before zero PSI.
  4. Disconnect battery NEG TERMINAL.  Crack a fuel fitting , on 16v front rail plug is most easy. Where goggles it may squirt on you.
  5. You are ready. No way is easier on this car. 
Hint, that big connector has  a large pink wire in the group, that is the PUMP power.
The remainder of this page explaining the 10 years of FSM ways.
Use MY way above and safe huge time and efforts. 

One more way, person said, "my exhaust manifold is missing" (or whole exhaust ,etc) and I dont want to make a racket. at 6am.
  1. Gas Cap off , (all modern cars run posative pressure in tanks !) 
  2. Repeat step 2 above,  pull the pink wired cable conn. per above (tail light) or pull the fuel pump relay. This kiills the pump.
  3. Remove the 4 spark plug wires , do not remove plugs from head.
  4. Crank the pressure off,  say for 5 to 10 seconds.  This wets the piston tops, but is better that, than  on you , or garage, etc. or blast in the face.
  5. This method fools the ECU thinking there is spark and allows the injector(s) to fire and bleed down the rail(s) and lines.
Rumor: Pulling fuses does this?, false, the fuses kill the Main relay and pump and ECU and kills the injectors dead, defeating the whole purpose here.
Many cars have a dedicated fuel pump fuse, sadly, not Suzuki.
FSM ways:  (a summary)

All modern EFI fuel injection system have large residual fuel pressures when the car is parked sitting ,and not running.
It can be as high as 65 PSI or more !    IT MUST BE BLED off first, before working on the EFI fuel systems. or gas will be all over the place ! LOTS !
Errata: 1996 Geo Tracker FSM  , Vol:1, page 6C6  figure 6C7 is dead wrong , shows Fuel Pump relay location for 95 and older. See 96 link below.
Some manuals (OEM too) are wrong on some facts, so use the pink wire colors, to find the relay.
There are many ways to do this job.
1: dead motor , no start and motor runs. 
2 if the motor starts then by all means , pull the fuel pump power running,  This is best done at the left rear tail light.
3: if motor dont run then , be out doors, and use lots of rags and eye protection  and bleed off the pressure at the filter test port (10mm screw).
Keep these rags out doors and away from people and belongings until fully dry.
 ( I use a nail on a tree and hang them high , from pets and kids)

This procedure is different that simply killing injections.  Pulling the relay allows you to RUN off the fuel pressure.
For doing a compression test we have 3 choices.
There  are 3 ways to kill  Fuel pressure and delivery ( flooding and fire safety)

Choices:
1 Pull the pink wired connector at the Left Rear tail light housing ( usually wrapped in gray plastic wrap) while running
2: Pull the fuel  PUMP  relay. (easy on 8v cars) while running.
3: find another fuel pump feed wire connector. (The FSM shows this path clear) while running.

Pulling the ECU power , kills the  spark and fuel injection defeating this purpose.

Step 1, find the fuel pump relay:  ( I never do it this way, but show how, for completeness)

 1989 to 1995 Early Relay location drawing.

1996 to 1998 location. (glove box removed) can be real hard to pull this relay

 1999 Vitara 2.0L

Grand Vitara's typ. 2.5L     And here too and 04'.

On 96+ year cars , I recommend Pulling the pink wired connector at the Left Rear tail light housing ( usually wrapped in gray plastic warp) MOTOR RUNNING.

Preconditions, if possible:
I'd wait until tank is low to  3/4, not full. To reduce the chance, of  siphoning.(if possible)
If you leave the gas cap on , siphoning will happen.

How to purge the gas from the Gas lines:   { MUST BE DONE BEFORE WORKING ON THE FUEL PRESSURE SYSTEM }
  •  Remove Gas Cap , bleeding tank pressure,  put cap back on loosely.  ( you may hear the whoosh sound)  Keep it loose.! So won't build pressure.
  •  Start engine, pull the fuel pump relay as shown above, and let engine stall. It will stall in 15 seconds or less.   (or pull Tail light pump feed connector !!)
  •  On most  early Sidekicks,, the FP relay is below the ECU on a green socket and has a pink colored wires leaving it.
  •  My 96 PR relay is top relay on passenger side heater. (LHD). Prior to 96 , its below ECU on drivers side. Look for pink wires, to be sure.
  •  The Engine dies in  seconds.  GOOD sign !   if not?,  read location links above more carefully.
  •  Start Engine 2 - 3  more times, to purge gasoline residual pressure.  If it don't start , GOOD !
  • ( I then disconnect the NEG. terminal of the battery for safety)
  •  Open gas lines with a rag, goggles and Viton gas proof gloves.   ( NEVER INSIDE ANY BUILDING, NEVER WITH OUT A FIRE EXTINGUISHER, at HAND and inside 10 steps.   5 steps away is Perfect !)  If gas keeps leaking after braking connections , the gas cap is not loose, or tank is too full.
  • If doing a fuel pressure test , follow the next steps.  There will still be some pressure (tiny) after a pressurization completion.
  •  Almost all  Kicks already have a built in  6 mm test port screw, at the Fuel filter Banjo fitting.(just in front of the fuel tank.)
  •  Place gauge at the line tap shown.  Take pressure readings, as shown on my Pump page,
  •  Or?  perform what ever fuel system maintenance you are doing.
  • On the 16v Sidekick you can get the factory RAIL adapters, go back, one page to see the choices of adapters.
  • You are Done doing what ever (fill in the blank) fuel system maintenance.
  • Tighten back the gas cap. (left loose on purpose , it might be a hot day  and gas expands on hot days, this can be dangerous with lines open !)
  • Put back the Fuel Pressure Relay.
  • Put back the battery cables if removed after relieving the pressure.
90's photos , typical;
1991 Real Photo:

91-95 FP Relay in the hand:

My 96 FP Relay pulled (top-one) (behind glove box)
Before touching Air bags and associated devices defeat those bags, see yellow connectors and wire sheaths?, "DANGER"
Q/A's:
The obvious, but not a stated fact in the FSM is that a car that  will not start, can not be bled  , by the above procedure.  oop's.
How do you relieve this pressure with out starting car? or with no starter or battery in car.?
If you have spark and car will crank , you could crank the pressure down. But that will take along time, and floods the motor (not good).
That is a good question.?
Answer:
Put a vacuum pump (MityVac or hand pump) to the Fuel Pressure Regulator (FPreg) nipple and pump it up and the valve will open and will bleed the pressure back to the fuel tank. Use rags to and goggles and catch the remainder so it does not hit you , in any way. Wrench on, rag on wrench end , turn.


Do not be tempted to hot wire the injector , you will burn it to a crisp.

If you have no spark, the Injectors will not bleed down the rail pressure.  (ECU safety feature in software (ROM))

The key on prime pulse (up to10x times) may bleed it down?, but is not a guaranteed, the prime pulse is for air purging only. (FSM quote)

Lots of questions , I get here , on this subject. Keep them coming.

Happy Trails
The above report is what I read in the FSM for from other mechanics,  I do not recommend  that YOU be working on your fuel system.
Hire a Professional !

I do NOT guarantee my accuracy nor my source (FSM) as being accurate, but I am sure spilled gasoline is unsafe, at all times.

Keep all fuels leaks , far from people , children  , pets , homes/ buildings and valuables to you and to others.

Have 2 Fire Extinguishers  close by, but not TOO CLOSE.  5 big steps or so...  (one might fail)
Never ever use water to put out a fuel fire. 
Have a friend attend you with  Extinguisher at hand, rated for fuels.
In a panic use a blanket.
Get and find expert training ,before working near fuel or air bags.   Do not guess.
I replaced my fuel filter , including supplied new copper washers (WIX).  The rear banjo than weeped, very slowly.
I had to take 1500 grit wet and dry sand paper wrapped to a small steel plate  and honed the banjo face.
This proved easier than dropping the tank and replacing the hose.

V2:

Jargon list.

FP = Fuel pump