Why no spark?

PICKUP not VAN sold new 6 engines, then, 5.0L yours.
when did it last run good, last week/month/year /????????
well in shop we'd check all fuses..
1995 is long in tooth for ECU problems bad caps
he ECU runs EFI and spark both ( a huge job)
runs ,stalls and not restart.
what you failed to I real testing and is not the starter at all.
first (besides good engine)
is spark if will not start, cranked spark is first unless you learned how to do he ECU CEL blink codes.(more later)
I will not stop and see what is there in your shop manual (service)
5.0L v8 gas, engine, this the horrible old TBI system? 1 injector>?
or is this the MPI , 8 injector engine,
has distributor spark and must be timed correctly to work
the CMP is in the dirtributor,
the CKP is on the crankshaft.
I test for spark first using both ways
a test spark plug, gaped right, (new plug not old) and if spark is good great.
if old plug is fouled;, carbon, oil soaked or soaking in raw fuel
the fuel seen now is flooding,
I then use a timing lite (yes even works cranking dead engines)
and make sure static time is correct the DIZZY.
if not it must be set correctly now. per the manual on car.
I use the light to make sure al spark wires spark(mag pickup lamp)
if not the distributor or the CKP sensor is dead.

if all that seems ok out comes my trusty Instant start spray can.
Air cleaner off, spray fuel here, 3 second blast , crank, and repeat
until it runs 3 seconds to burn up you fuel sprayed.
see? the engine is not dead, now, or IS deaD.
IF FLOODING SEEN, crank with foot throttle depressed WOT
and the trick cuts off the injector and the flood is cleared
even starting an old engine like this with 5% throttle can hide a bad IAC air valve and allow it to start and the a active right foot to keep his beast running.
but spark is first it must be good x8 and battery fully charged.

this 5.0L is a TBI injected engine, 1/2 injectors not 8 with MPI
some have a starting only injector then the signal; main to run
theTBI is old and its pressure regulator can be bad./

one trick I use (means tactics) Is that I kill the fuel pump fuse or its relay pulled.
this hides the bad TBI fully and now test fuel works all I want showing me it is just bad spark or bad fueling just doing that.
the TBI can fail 3 ways, dead, way to lean or way to rich
the latter is flooding and WOT cranking can clear floods.

the goals ARE TO FIND?.

1. bad engine
2. bad spark
3. bad fueling

OR CATS MELTED, OR EGR STUCK WIDE OPEN BUT THOSE TO 2 THINGS MAKE THE ENGINE BAD. SO IS THAT.#!

TBI CAN BE A BIG PAIN
NOW THE FLASH CODES, EVER LEARN THAT/
THIS PRE 1996 CAR USA HAS OLD CHEVY OBD1 DIAGNOSTICS
most folks never heard of it now but gee it is in the manual for sure.
fl\ash codes (blinks) code 13 to 55 or more with A/t box.

steps to do this,
key off
find ALDL connector (DLC modern named ) data link conn.
see my photos. (books says under DASH) some near column
The diagnostic trouble codes can be read by grounding test terminal B. The terminal is most easily grounded by connecting it to terminal A (internal ECM ground).
jumper B to A
THEN KEY ON AND CRANK THE ENGINE (BATTERY ALWAYS CHARGED FULLY BY THE TECH)
AND CRANK FOR 10SECONDS, NO MORE
THE RELEASE THE KEY (NOT OFF)
SEE THE LAMP BLINK OUT FAILURES CODES.AT CEL CLUSTER LAMP, THE CHECK ENGINE LIGHT BLICKS AND THE LAMP MUST BE GOOD. (many are removed by evil sellers)
quote
flash Code 12. The code will display as one flash, a pause and two flashes. Code 12 is not a fault code. It is used as a system acknowledgment or handshake code; its presence indicates that the ECM can communicate as requested. Code 12 is used to begin every diagnostic sequence. Some vehicles also use Code 12 after all diagnostic codes have been sent.
then other blink codes are next if stored or are live errors.
2 kinds live and stored, both matter to any tech.
after Code 12 has been transmitted 3 times, the fault codes, if any, will each be transmitted 3 times. The codes are stored and transmitted in numeric order from lowest to highest.
sorry for long post but 1995 cars are super hard to diagnose.
even bad CAPS in the ECU are common now, and show stoppers.
CODE 42 OR 43 IS BAD SPARK , I'D NEVER Forget to ask the PCM what errors there are, ever, ask it and win,
also the lack of errors has meaning too.
full stop this is what I'd do the first hour.

ALDL jack (assembly line data link ) conn. CHEVY ONLY !

You drove with a flashing check engine light and then with it on solid. Flashing check engine light means STOP DRIVING and get it fixed. So this sounds like an abused and neglected car to me. Get the trouble codes read that are stored in the computer. Check for good fuel pressure and spark. Fix one or both.

Does it start

Remove No 1 spark plug turn engine till compression felt. align mark on crankshaft pully with mark on timing cover , distributer roter now points to No 1 on cap. Firing order 6 cyl 153624 4 Cyl 1342. check which roter turns and connect cables as above

standing passenger side vechicle with crankshaft pulley facing your.number one sparkplug location should be at twelve Oclock position.you need to know cylinders locations front cylinders left to right is 1 3 5 7 and back cylinders left to right is 2 4 6 8 and firing order is 1 8 4 3 6 5 7 2 your ignition timing need to be 10 degrees BTDC AT 800 RPM. YOU SET TIMING YOU NEED TO DISABLE SPARK ADVANCE BY CONNECTING JUMP WIRE OR PAPER CLIP STRECTCH AND BEND YOU NEED TO CONNECT JUMPER WIRE TO A AND B DLC TERMINALS. if ignition timing way off you wont get no spark.but check ignition fuse and make sure distributor cap and rotor good shape also spark plugs and wires.if all is good your ignition module or ignition coil bad.the 4.9 can be time if you have 4.6 engine cant adjust ignition timing PCM control timing.code scan vechicle first before buying new parts.look for ignition module or pcm fault codes.look for faulty crankshaft sensor or camshaft sensor.many things will cause no spark conditions.

Misfires are caused by fuel delivery problems, injectors or too rich or weak. Spark issues, coil, wires, spark plugs or the cap and roter.
I could also be a loss of compression. First thing to check is the easiest... spark plugs, spark and cap and roter. Also the cheapest.

Its the fuel pump.

depending on the year of this car, a flashing check engine light means a misfire, this may be due to a bad spark plug or the wires to plugs, you can go to any autopart store and they will scan the computer and give you an idea of the problem and give you the codes, what happens is the computer sees a problem and it turns the light on to warn you of the problem , it then stores a code, this code will tell you what part of the system is failing or failed. if you can give me the year ,make and model with the codes the autopart store gives you i can help you further, hope this is helpful. good luck.

the 3.5 to 5 volt signal is a reference signal generated by the ECM. I believe the current runs through the check engine bulb before it comes to that particular connector. what you need to do is perform a instrument cluster bulb test by turning the ignition switch in between run and start. in other words you pretend like you're going to crank the motor but you don't turn the ignition switch all the way to where it actually starts cranking in the engine. just before the switch engages the starter of your instrument balls should light including the check engine light bulb. it does not light you need to pull the instrument cluster in replace the bulb, it is probably burned out. good luck .

3 things make an engine run, fuel, electrics and gearing, first thing, remove the cap and crank the engine, determine if the rotor is moving, this will eliminate a broken cam, sprockets, chain or broken teeth on the distributer. next with the ignition lights on rotate the roter button by hand in between contacts, you should hear and see small spark, replace the cap and crank engine with a plug lead off, ask a friend to see if it is sparking onto metal nearby. Next remove fuel line and crank engine to see if fuel pushes from the line. then that leaves gearing, timing must be correct, check the lead numbers are in correct firing order and timing is right. Hope this guide helps you, Good luck