This is a long story but through two different diagnosis it came to that the PCM was toast. I have since replaced it but still no start. (I haven't gotten to a more in depth check of everything yet) For the time being I am just curious to know what the following might mean. When I try to start the blazer it turns over and when I apply the gas it makes a thumping sound. What could this thumping sound mean? Is it possible that the distributor is 180 degrees off or no correlation to any of this? (I ask because what lead to the no start was replacing the lower intake manifold gasket)

Thanks

 

I would go through the distributor installation one more time. There is a post in the Tech Article (DIY) section entitled EDI Engine Timing that will help.

 

Thanks for the reply, if there is hope the thumping might indicate the distributor is just installed wrong then I will go through the trouble of trying to install it correctly.

Even if the distributor is wrong would I still get spark through the plug wires?

 

Update: I finally got it to start today. After talking with someone it made me think about what I had plugged and unplugged, I remembered I had a very had time plugging in the crankshaft sensor. I pulled the connector today and checked the sensor. I found that one of the pins was bent flat against the inside of the connector. After fixing this and reconnecting it started right up. I put the old computer back in and still starts. This bent pin would explain why it wouldn't start and why a scanner couldn't pull any codes. Thanks for the help.

 

That is a definite problem! Thanks for the follow up! You have to be quite careful with the connectors on these trucks.