My friend has a 1997 GMC Sierra 6 cylinder VIN W 6-262 (4.3) CPI

First, what does the CPI mean?

A few months back he got a CEL that was a bad coolant sensor. He changed out the coolant sensor and the truck ran fine after that. Yesterday he went out and stopped for petrol at a Texaco station, drove a few miles, and then came home and parked the vehicle. Today the truck refused to start, it would turn over but not start. I told him to check the coolant connector to see if it was loose. While I am waiting for him to do that tomorrow, I decided to see what the group here thought.

He told me:

"It would not start or even sound like it was firing, yet after letting off the key, it'd suddenly lurch in trying to resume starting

It has started like new (and has a brand new battery) since the sensor was fixed, never any hesitation at all

start on first turn of key"

Any advice? The lurching thing may be a key; not sure why it would lurch like that.

cpi is the most rediculas injector design ever, the injectors and fpr is in the intake to get all carboned up and makes it hard to work on. i dont think thats the issue however, it seems like maybe the fuel pump maybe bad. if you turn on the key and dont hear it prime thats a good indication of a pump problem but make sure you check for power at the sending unit connector because they have alot of issues with the connector itself. there is a delpi sending unit with a better connector and a different level sensor and comes with the wires you have to solder and heat shrink them into the truck harness

Yea, I'm leaning towards the pump myself. Another quick thing you could try is, get underneath, find out exactly where the pump sits on the bottom of the tank, and bump that spot with a rubber mallet or the ball of your fist. Then try and start it.

Hey Justin, think the ignition switch might be a cuprit too?

My friend told me today that his truck "... started! First try!". He said "It was running just a tad rough, like a slight miss evry so often." It was wet weather in his location at the time and the weather has cleared. So my thought was ignition problem due to the wet weather and could still be causing the miss since he has not driven the truck; just started it. A month or two back, the truck gave some problems driving and threw a code for the coolant sensor. He replaced the coolant sensor and put in a new battery and the truck has been starting and running fine until the other day when he went to leave and it would not start. Those that know more about these engines please advise.

the temp sensor is not going to cause a no start. you could get a water bottle and mist ign components to see if something makes it stumble

You know, my 2000 Blazer does the same darn thing. When its wet out, it runs like crap. It has the 4.3 CPI also.

I've been researching my issue recently and have come to the conclusion that the distributor needs replacing. It does have play in it and fits the symptoms. The gear at the bottom of the distributor are known to wear out.

Just thought I would throw that in, might help. ???

does your fancy new program read cam retard? ive read that if the dist gears are worn the cam retard will be out. supposed to be 0 +- 2. i dont have anything that reads that.

worn out gears are not going to cause moisture issues, however the module thats in there may.