Finding bad cell in hv system. How do I remove the rear seat. After the service plug do you diconnect the cells from the busbsr and test them one at a time.

no engine told at all, and is an engine/efi question. pure.
backfires to air clear or to rear tail pipe or muffler explosion.???
we can no hear it back fire and matters huge.
if only muffler explosion that is super rich fueling.
right fast foot can not save the stall right or even gets you full engine power doing so???????
your gm car has vin code and 8th digit is engine code
best is know what's under the hood first to fix any car.or truck
otherwise answers will be wrong,
a real shop opens the hood and goes AHHHHH
me zero. ahhhh
Avalanche 1500 or 2500?????????????????
good no Diesels here. (USA answers me)
5.3 L LM7 V8 (gasoline)
5.3 L L59 V8 (gasoline/E85)
8.1 L L18 V8 (gasoline)

we can not guess service history of any car /engines
21 year old spark plugs? no way are those good if true.
no miles on truck told. 250,000 miles? more?
got bad fuel, truck ran last month ok or last decade ok? history matters on all machines. for sure.
check all fuses yet, as in ALL
scan the PCM for errors called DTC and it shows p0300 ?
or other DTC errors. all modern cars are scanned first.
or go broke guessing you will.
bad spark the 5.3 runs 8 cops, but are not WELL cops they are hv wired cops.(packs) the 8 HV wires sets are never good at 21years later. they fail, hard.
as see here.
https://www.rockauto.com/en/catalog/chevrolet,2002,avalanche+1500,5.3l+v8,1377244,ignition,spark+plug+wire,7224


there are lots of causes under page 1 basics rules
bad engine,
bad spark
bad fueling.
compression bad. below 150 PSI or 0psi.oops. bad engines do not burn or make full power. even vacuums test bounce, no good that.
then spark we test spark on all 8 plugs( using tools for all tests)
last is fueling , good fuel,? , fuel pressure at spec,cranking and idling.
fuel pressure reg tests pass FPR.
this 5.3 runs a TBW system , throttle by wire if DTC error for it show up it will never ever run right .

there are 50 causes and up to 20 tests using tools to find them all
gue$$ing is not going to be cheap or worse. adding bad parts over good. oops. now 2 hard failures.

so what is the plan? nobody ever says hear.
buy tools and do the tests
?
or just want blind men to guess 50 times.
or get it service in a real show with real tools and skills.

now my silly guess
valve spring 1 cracked and valve sucked, and compression dead here#1. and vacuum nasty bounce ,PCM goes mad with nasty vacuum. it sure will go crazy. EFI just hates bad vacuum. MAP sensor goes nuts and sends nuts readings to PCM, and PCM is clueless what to do. for a fact. ( it will try and fail hard)

1 of 50;

gen 3 ford.
YOUR MECH LOST ALL HIS TOOLS AND TRAINING?
THE ENGINE THAT SHUDDER, MEANS MISFIRING
AND HE SCANS THE PCM NEXT ,IF NOT HE IS A POSER.
SCAN THE PCM SEE P03xx errors and now you have bone to chew.
if guessing why not do a spark tune up first , not just PLUGS
2 engines that year,
1997 , is old and spark parts fail, this is 100% normal, to fail zero service, filters, spark parts, fluids, belts.
no engine told at all or VIN or country, we can not guess what is under that hood, and make accurate answers. ever.
this post is generic for your lack of facts.
best of all scan as the engine misfires
can it failing is best, some error clear fast if the end.
so we scan and drive and log all DTC stored or live or pending.
some mech are too lazy to do the real job, test drive it.

1: engine compression test all good at 150psi up. all 4.
for sure after that new belt , we do #1
2; spark parts fresh, plugs ,and wires hV and if cops new boots.
3: fueling fails. even bad fuel. low fuel pressure, bad pump, bad FPR . injector leak down test, injector balance tests. ????

i see 4cops (extended) and each as a HV spark wire
I use NGK wire sets (blue) or mag wire. for best spark.
those HV wires are not any good now this old ever.
there is and ICM module too ,to make spark.
HV means high voltage spark wires sets. 20kv+ volts.



2 engine here, 97


2.0 L SPI2000 SOHC I4
2.0 L Zetec DOHC I4

"SUZUKI SWIFT,no country or engine told at all)_ hard to crack nut.
miles told.
3 classes of gas(PETRO) mr Otto cycle engines
bad cylinder #4rear compression test fails hard.
P0304 scan errors (DTC)
bad spark parts, plugs or HV wires or coil pack #4
bad fueling even bad fuel.
the car with other names sold all over earth,badged names odd.
1.3 or 1.5L engines and 4 cylinders., transverse mounted.
you said rear and that word tells me you scanned the PCM to learn that. fact
and is not just spark, it is 3 causes.
engine. ,spark, and fuel 1,2,3 cause
and we test to find them but sure new park plug times.
we pay here in USA only $1.50 fora spark plug so is simple thing
also called tune up and if the COPS pulled the boots are bad THOSE TOO.

You may have a bad gauge or fuel level sensor, testing will need to be done to find which is bad, the level works with the fuel pump so it would not be a fuse if car runs,

Remove the rear seat and make sure wiring to top of tank is good,if you locate wiring to sender and connect ohm meter to ground and sender wire you can test it, you would need to remove the unit from the tank to test, this way you can move float up and down to check readings.

This fuel punp is not removed by dropping the take like so many. It is under an access panel under the rear seat. To change the fuel pump follow these instructions.
1. Determine which fuel pump your Mitsubishi Galant will need. This depends not only on the make and model, but also the engine size.

2. Prepare your car for service to the fuel pump. Relieve the fuel system pressure and disconnect the negative battery cable with a socket wrench. Take out the rear seat cushion. You will need to pull the seat stopper out and lift up the lower cushion. You can now remove the access cover.
3. Unplug the fuel pump's electrical connection and disconnect the fuel send and return hose. Remove the retaining cap for the fuel pump with tool MB991480 and remove the fuel pump.
4. Install the packing material on the fuel tank. Replace it if the packing material is damaged or deformed. Install the new fuel pump and align the marks on the floor pan and fuel pump.

5. Complete the installation by reversing the removal procedure.

This should take care of you. Let me know if this helped you.

The leads should be reversed to get a reading on down position ,tap the window motor gently as you push the switch and see if that helps .
If so the motor is bad.........also on alot of vehicles the rear windows don,t go all the way down ,it,s a safety feature for kids or pets in the back seat.

The fuel pump IS located in the fuel tank. It is easily accessed in this particuar model, under the rear seat. If you have an arm reat in the middle of the rear seat, you'll need to go in through the trunk. Remove the cover from the the far back, between the back of the rear seat and the trunk space. Remove approximately 4 to 6 screws in the center piece of cardboard that attaches the armrest and rearseat to the cross menber of seperating trunk from seat.
From the back seat, grab the top of the back rest of rear seat, PULL HARD forward on left and right sides . This should disconnect the top. Then, on left + right-sides, toward the lower cushon, there will be a bolt, remove them.
Then pull up the bottom cushion.
In the middle of the floor you have left, where the bottom cushion once was, you will find the top of the fuel pump access. From the top there is a cable that goes toward the driverside, follow it to the connector which should be cover by a small piece of foam. Remember to diconnect the pump before attempting to service or replace it.

Ok, lift the rear seat on the drivers side, underneath you'll see either a grey or black box, inside I believe you're auxillary power fuse is number 46.

I have had the exact same problem , the actaual cause of the seat not sliding back is due to the small cable retaing clip which fastens at the underneath of the seat this is a very common problem and is very trickY to get to as you say the rear panel appers to need to come off , it does not, you axs the small clip from removeing the liners at the very bottom of the seat where there is a footwell light , when you axs this area you be able to get to the clip or the actaul cable ,to which ever is broken,,

pull up to remove the lower seat cushion. remove the bolts for the rear seat cushion the bolts are at bottom of rear seat frame.. lift it up to remove it..