1989 GMC engine turns great , no spark at coil or plugs, had coil tested and repalced- new rotor and cap. not sure where to go next

ever see the truck run perfect before, or not in 10 years?
C2500 right not k2500 ,pickup.
NO ENGINE told ,4 engines 3 gas 1diesel.
but is gas so 4 engine not told (no fun there, blind)
4.7 to 5.7L and 5.4L gas.
crankshaft and cam forgot to say sensor?
CAB means distrib CAP .
rotor sure.
why not new SPARK PLUGS first and for sure those ratty old HV spark wire, useless, I run NGK mag wires.

battery good, cranks fast and engine spins fast and does not start.
and engine compression is good
and we test that spark is good on all 8 cylinders not just one,all 8 are test
and also tested for spark timing. for sure if distributor was removed, or set loose at base and timing lost.

if all that is good the engine now runs on spray test fuel in a can. for 3 seconds, even with fuel pump fuse pulled.
if you get this far,
we check fuel pressure next and even for bad fuel.
no history of car told
bad fuel ,old rusty tanks wreck injectors.
26 year old truck,.

things bad that old are, all fluids and belts
fuel filter packed in gunk and rust.
thermostat bad.
spark parts bad, cap/rotor wire sets x8 and spark plugs. (or timed wrong or put back wrong firing order)
injectors clogged, bad fuel or rust in the tank
bad FPR, bad map sensor.(or only clogged)
or bad fuel pump if pressure is low and FPR not bad.

most of my tests all take tools and meters
a tech can not fix cars lacking his tools.
and skills to use them./
even a timing light is needed on all distrb cars
and all EFI cars a fuel pressure gauge.
and compression gauge
and vacuum gauge.

fuses good< oops
scan the PCM see errors cranking OMG it tells you why:? sure can.
forgot the 6 new spark wire plug set, replaced 1 by one never all at once, 6 new OEM type spark plugs and gaped correctly
22 year old spark parts are no good ever.
test for spark on all 6 yet, spark is 1st or there can be no FIRE.

4.3L cranks but will not start and run and stay running.(problem1)
fire cant be seen, but spark can.
1,2,3 engine,spark, fuel good 1,2,3 in that order
spark and fuel can not run a dead engine, so 1 is first engine'
compression good 150psi up not lower, all near same
next is spark if EFI sees spark
actual fuel pressure not told just OKay. pressures matter big time in EFI, and at cranking for sure. then idle and WOT later.
engine is free running so all tests are safe, cranking too.
the service manual covers all fuel checks cranked, balance test and leak down tests.

watch scotty
https://youtu.be/064Ilsz8Fzg

Repalce the plugs and wires/ boots.

I guess you could have the ignition analyzed on an oscilloscope. Maybe a tech could see something then.
I always heard the only gap was the spark plug gap-the rotor has no gap-are you sure you got the correct rotor? And does it touch the top distributor cap coil wire tower?

Let us know. It is a mystery worthy of a solution.

New parts can still be bad , check for cracks also check wires for white arc marks on each other or where they might contact a ground source .

if im correct in saying this, i think there is a small cylindrical looking piece with one wire comming out from the front in the distributer under the distributer cap next to the points this is could a condenser you could try changing this for a new one all so check the gape your points make if to small you will get no spark as well if to big

Hi, Ok you have confirmed that it's not a fuel problem. You need to check for spark. Pull the coil wire off of the coil(secondary lead-looks like a spark plug wire) Have some one crank it over and listen for a popping sound. IF yes, spark is at the coil, that means all ignition sensors are working. Next check for spark at ends of wires after cap. IF no replace cap and rotor. IF yes remove a couple spark plugs and check for fouling(wet, fuel etc...) IF yes replace or clean plugs and retest for starting. IF no spark is present at coil you need to scan computer and watch for rpm signal. IF no rpm signal, replace crankshaft sensor with OEM delco part. BIGGEST problem with these engines is Cap and Rotor burn out.

Check the coil wire for spark at the distributor cap. If you have spark there, check the rotor button and the cap for corrosion or failure.

dist. module could be the problem but check and make sure the rotor is turning

There is no test for module in distributor, but they often cause this kind of problem. Also while in there, check the pickup coil wires to make sure they are intact.