Truck shuts off while driving?

DAVID MUSTOE

MEMBER
1999 CHEVROLET SILVERADO
5.6L
V8
2WD
AUTOMATIC
210,000 MILES

As of now this has happened twice in one day. Two weeks ago, I had the fuel pump replaced. Ran great no problems. Then while driving on the highway it stalls. I waited a few minutes and it started and continued to work which was thirty miles away. After work I went to dinner with co-workers. Left the diner and it stalled at signal light. Try starting no luck, tried again started right away and I continued to drive thirty-five miles home.
Prior to all of this I had a check engine light come on. I was on my way to work so I stopped at the auto store to use their scanner and the code was for a temperature sensor replacement. Bought sensor and proceeded to work. When leaving work there was no check engine light. A couple of days later the light came on again. Drove truck later that day and no check engine light. This happened for a week and now it has never come on again. I never replaced the sensor.
Some other guy was having stalling problems and you asked him about temperature sensor. I know it is not the fuel pump I just replaced two weeks ago. Could it be temperature sensor?

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,755 POSTS

Hi,
That is a good question. The coolant temperature sensor signals the PCM the temperature of the engine. The PCM uses this info to determine the air/fuel mixture needed to run the engine. If it is completely off (the sensor sending an inaccurate signal) the PCM will provide the wrong mixture which can cause stalling, a rich fuel mixture, no start conditions, and so on. I would replace it if you already have the part.

On the other hand, there are other things that can cause this to happen. However, since it always starts right back up for you, it will be hard to test without removing it. The part I'm referring to is the crankshaft position sensor. When they begin to fail, it is common for them to be adversely affected by heat. Often, they require a cool-down time until they work again. Take a look through this link and see if it mirrors what you experience:

https://www.2carpros.com/articles/symptoms-of-a-bad-crankshaft-sensor

As far as the coolant temp sensor is concerned, since you already have it, I would replace it. I attached the directions below specific to this vehicle. I assume you meant a 5.7L and not a 5.6L. If I am incorrect, let me know the engine size so I can get the correct info.

Take care,

Joe

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