Stall And No Start Sierra, What's Wrong?

kevarsenault · December 25, 2007

Goodday and a Merry Christmas,

I've got a 99 Sierra(192,400km) 1/2t 2WD, V6 Auto with no start/ Stalling issues. Hoping someone's run into the same problem as me and can give me some advice.

The truck started stalling randomly about 2 weeks ago without any indication that it was about to. It would stall at any Speed, RPM, Gear, Temperature, and Load. When it was running it would run perfectly without any sputtering or anything. The truck has now been sitting for the past week as the problem became so bad it is not reliable to take on the road and sometimes will not start at all. Gas has been replaced, and gasline antifreeze added.

Work done/Things done:

- New Ignition Module

- New Coil

- Brand New Coil to Cap Wire

- Cap and rotor only have 30,000 Km on them, were removed, inspected and cleaned

- Plugs also have 30 K on them, inspected and cleaned

- Distributor checked to see if it had worn and retarded itself, it had not and seems tight and fine.

- Power was checked at connectors to Coil and ingnition module...correct volts were there

- Engine ground, Chassis ground, inspected and clean

- Has fuel pressure, fuel pump works fine

- Engine scanned for codes, none shown

- No lights or warnings

- Recent new battery

- Radio deck installed 8 months ago. Removed unit and checked wiring to see if Theft system was set off. All wiring there seemed fine. (And from what I've read the theft system shuts off the fuel system and doesn't mess with ignition.)

Here's the weird part...When I had all the plugs removed to inspect them I had someone crank the engine over while I watched for spark. The spark would come and go whenever it felt like it it seemed. They would either all fire perfectly or wouldn't at all.

I have now sunk some coin into it and a considerable amount of time on it and am honestly out of ideas and am looking to see if anyone has suggestions or solutions to help me out.

Any suggestions or help would be greatly appreciated,

Happy Holidays!

DDT1 · February 28, 2008

Goodday and a Merry Christmas,

I've got a 99 Sierra(192,400km) 1/2t 2WD, V6 Auto with no start/ Stalling issues. Hoping someone's run into the same problem as me and can give me some advice.

The truck started stalling randomly about 2 weeks ago without any indication that it was about to. It would stall at any Speed, RPM, Gear, Temperature, and Load. When it was running it would run perfectly without any sputtering or anything. The truck has now been sitting for the past week as the problem became so bad it is not reliable to take on the road and sometimes will not start at all. Gas has been replaced, and gasline antifreeze added.

Work done/Things done:

- New Ignition Module

- New Coil

- Brand New Coil to Cap Wire

- Cap and rotor only have 30,000 Km on them, were removed, inspected and cleaned

- Plugs also have 30 K on them, inspected and cleaned

- Distributor checked to see if it had worn and retarded itself, it had not and seems tight and fine.

- Power was checked at connectors to Coil and ingnition module...correct volts were there

- Engine ground, Chassis ground, inspected and clean

- Has fuel pressure, fuel pump works fine

- Engine scanned for codes, none shown

- No lights or warnings

- Recent new battery

- Radio deck installed 8 months ago. Removed unit and checked wiring to see if Theft system was set off. All wiring there seemed fine. (And from what I've read the theft system shuts off the fuel system and doesn't mess with ignition.)

Here's the weird part...When I had all the plugs removed to inspect them I had someone crank the engine over while I watched for spark. The spark would come and go whenever it felt like it it seemed. They would either all fire perfectly or wouldn't at all.

I have now sunk some coin into it and a considerable amount of time on it and am honestly out of ideas and am looking to see if anyone has suggestions or solutions to help me out.

Any suggestions or help would be greatly appreciated,

Happy Holidays!

I hope I'm doing this right - never done a forum before, and I decided to sign up so I could answer your post. Wish I had seen it two months ago. I had this exact problem in my 87 V20 and did most of what you did before giving up and putting it in a shop, where they gave up and called the GM Techline for advice. It turned out to be the distributor shaft. Apparently the magnets on the top of the shaft had lost their magnetism and the pickup coil wasn't getting triggered consistently. I'm not sure what type of distributor a 99 has but if it's similar to the 87, this isn't a difficult repair if you have removed a distributor and the part costs about $75 from GM.