OK Guys and Gals, here we go. New to the forum and I've got a new one. Worked for years on GMs but I need some help!!

I have a 2004 Silverado with 4.3/Auto. It has 157,000 great trouble free miles until NOW!!!!

Condition: Ran rough at times, would just cut off at times, sometimes would immediately restart. It would make a "run on" type of noise (like an older car "dieseling" after cutting off) sometimes after dying. As of now, it will not start at all and I have the following:

1. No spark at coil/no spark at plugs
2. Power to coil (12 volts)
3. Injector Pulse IS present
4. Strong fuel pressure (55-60 psi)/volume pumped good
5. No DTCs present
6. distributor rotation confirmed
7. plugs HAVE fuel on them after cranking, so I assume injectors are functioning correctly.

Items I have checked/replaced:
1. Ignition module
2. all ecm/ignition fuses(that i can find)
3. coil
4. dist cap/rotor
5. pickup coil/cam sensor
6. crank sensor
7. No fuel leaking into intake plenum under regulator/throttle body.

Still no spark.

Any ideas???

Thanks for any and all help!!

Chuck

 

I know you said you checked the Ignition module and I assume it tested good and I assume you changed the coil? what about testing for spark the old way (screw driver in the wire from the coil). How about a fusible link? do they all check out good? Also the grounds will have a VERY big effect on this too.

 

I've looked at all the fusible links I can find.....Ya, I used a spark tester, and to verify it's operation, a good ole screwdriver too.....I'm gunna have to find all those link locations and look at some grounds too.....Thanks....

 

Did you change the coil packs out? I only ask, because you sid in your 1st post that you had no spark at th plugs or coils...

 

Uhhhh what distributor cap/rotor?????

 

I was thinking the same thing....but I dont have one I can put my hands on so I didnt say anything

 

It's a lowly 4.3 liter v-6, which has only 1 coil, mounted on the intake next to the ignition module. It also has distributer/cap/rotor/pickup coil, which is mounted in the standard Chevrolet position, rear of the intake manifold. Totally different than the coil over plug setup on the newer gen III engines (4.8, etc).. Ya, I tried a new coil too.....

 

Oh ok. I did not know that of the 6 cylinders!! That run on you were talking about was probably from timing being to advance. So I would say for sure the problem is somewhere in the ignition. How does the tips of the inside of the cap look? And the rotor tip? There is a part that sits under the rotor I think that will wear out. I cant remember what its called. Correct me if I am wrong please. Its been a little since I have seen a distributor.

 

I am having the same problem. It started out as a miss then moved up to dying which always cranked. Then to dying and not cranking. I changed the fuel pump no difference. The rotor button and dist. top changed and it ran fine for 2 days then boom again. Next was a new coil. No fire with the screwdriver trick in the new coil. There showed a code for Mass air flow sensor. New one started it just fine and drove it all day. Boom again. New ignition module no help. Now what? I has a very good mechanic and myself bumfuzzled. Help us if you find your problem.

 

my 04 silerado with a 5.3 has the same prob no spark at times from minites to hours and random miss firing at all speeds and temps no codes new crank sensor new MAF sensor I am a professional mech to and am looking for in put before i replace the pcm