1990 silverado 1500 5.7L

[BGOOD1985]

On my 1990 chevy 1500 5.7L What would cause me to not have spark on some cylinders but i do on the others? Ive changed the ignition coil ignition module and plugs almost brand new wires.

[Blue Bowtie]

That leaves the distributor cap, and as a remote possibility, the rotor.

[BGOOD1985]

Sorry ive changed the cap and rotor as well. I thought that was obvious when i said i changed the ignition module as the ignition module is on the back of the distributor cap

[Blue Bowtie]

Did you happen to note the amount of runout/play in the distributor shaft when the rotor was changed?

[BGOOD1985]

There was little play in the distributor, however, the pick up has corrosion on tbe plug and the plug cover is broken. Goin to change the distributor. Will respond with what happens after that but I had to order one so it will be a while before i do

[BGOOD1985]

[quote=Blue Bowtie;7233107]Did you happen to note the amount of runout/play in the distributor shaft when the rotor was changed?[/QUOTE
]There was little play in the distributor, however, the pick up has corrosion on tbe plug and the plug cover is broken. Goin to change the distributor. Will respond with what happens after that but I had to order one so it will be a while before i do

[BGOOD1985]

Ok changed distributor, got spark got fire compression is good still wont start..... any ideas?

[Blue Bowtie]

Four things are needed to run - Compression, ignition, fuel, and those elements coming together at the right time. You have ignition and compression. All that is needed is fuel in the chamber (good fuel, not 2 year old fuel) and the proper valve and ignition timing.

[BGOOD1985]

I have done all of that got spark got fuel got compression.. im was thinking EGR valve

[maxwedge]

Ok, have you sprayed some carb cleaner into the intake, see if it fires?

[BGOOD1985]

Yes and got nothing

[maxwedge]

If you had good spark and timing, it should at least sputter , a stuck open egr would make hard to start.