1988 Chevy Truck No spark at plug

Remove distributor cap and have a helper crank the engine for you as you check if the rotor
rotating
if not remove distributor and check gear and also check timing

Can you clarify some thing for me
with engine cranking you have no spark you moved the distributor and you have spark know put no start
is that correct
or you have no spark at all
do you have spark at the coil
check coil and connector
one way to check if the rotor and crank shaft timed is to put the crank shaft at top zero center
check if rotor at or close to # 1 spark lug wire at the cap

I would pull the distributor and look at the gear, sounds like it may be partially worn out
Could also be a bad ignition module, they were known to fail

You can read guide below, it will help you with your no start condition

https://www.2carpros.com/articles/car-cranks-but-wont-start

https://www.2carpros.com/articles/how-to-test-an-ignition-system

OHM check pickup coil see diagram

A infinite resistence in B 500-1500 ohms

Hi tdecker85087 and TY for the donation

Check and test the distributor pick-up coil and air gap-also double check the cap and rotor contacts-if there's spark out of the coil-it should have spark at the plugs if cap and rotor good it has to make it out there to get to the plugs

DTC's

12
No Distributor pulses

13
Oxygen sensor

14
Coolant Temp sensor circuit

15
Coolant Temp sensor circuit

21
Throttle Position Sensor

22
Throttle Position Sensor

23
Manifold Air temperature sensor

24
VSS (Vehicle Speed sensor)

25
Manifold Air temperature sensor

32
EGR system

33
MAP sensor or MAF sensor depending on engine

34
MAP sensor or MAF sensor depending on engine

35
Idle Air Control Valve

36
MAF Burn-off circuit

41
No Distributor pulses, cylinder select error

42
Electronic Spark Timing or Bypass fault

43
Electronic Spark Control fault

44
Lean exhaust

45
Rich exhaust

46
VATS system fault

51
PROM fault

52
CALPAK fault

53
System over-voltage

54
Fuel pump circuit

55
ECM fault

61
Oxygen sensor fault (degraded sensor)

Welcome to the forum. Is there a pulse on the negative/tach side of coil, use a testlite? Any codes?

With bypass ignition, it is the ignition module that controls spark under 400 rpms. Over that, the ecm puts 5 volts on tan wire with black tracer. That signal tells the icm to use the signal on the white wire for spark timing. If signal on the tan wire and none on the white, there may not be any spark. Whether the problem is the wiring circuit or ecm?

Make sure the distributor is getting power from the igniton switch-if so all you got left now is the ignition control module/and distibutor pick-up coil

My info shows your vehicle is fuel injected. Without the rpm signal, there won't be any spark or injector pulse. The rpm signal comes from the ignition module, but, without the trigger signal, the module doesn't know what to do. The trigger signal comes from the pick-up coil assemble. I'm not telling you to replace anything, right now I'm not quite sure what's causing your problem? Is there B+ at the coil, with the key turned on? I have seen procedures for testing the circuits to this type coil, but, my memory fails me.

As far as the fuel pump, my info shows there is an oil pressure switch in the fuel pump circuit. After you crank the engine enough to bring up oil pressure, that switch closes, and the pump will run, but, it doesn't matter if the pump does run, cause without the rpm signal, the injectors won't pulse.

Maybe someone can jump in on this :)

The computer will switch to a default parameter or value if a sensor is whacked. The adjustemtn will keep things working on a temporary basis.