Still chasing why my truck keeps dying

[Mike Napolitano]

I guess the question is:

What could cause a truck to die...only in gear... coming to a stop (applying the brake)... forward and reverse... and randomly... while maintaining fuel pressure at the test port.

If you have good fuel pressure and dies when coming to a stop you probably have an injector leaking down, this was common on the vortex set up. Also check the coolant temp sensor because on my 97 chevy suburban k1500 5.7 and my father's 98 Chevy suburban k2500 7.4L the coolant temp sensor went bad but were not setting codes until they completely failed but prior to light coming on they had an extended crank time to restart. If either of these two issues are the problem hold the accelerator pedal to the floor at wide open throttle then turn the ignition on and this will give you what GM refers to ass clear flood and will cut off all fuel to engine and if engine starts up without delay then check coolant temp sensor volts and leave fuel pressure gauge connected and after key on engine off and let truck truck sit and see if pressure drops also crimp the return line so nothing leaks back to gas tank.

 

[Mike Napolitano]

Additionally to my previous post the leaking fuel injector and coolant temp sensor issue the dying and hard starts are more noticeable when vehicle engine is warm to hot

 

[Jared Jackson]

If you have good fuel pressure and dies when coming to a stop you probably have an injector leaking down, this was common on the vortex set up. Also check the coolant temp sensor because on my 97 chevy suburban k1500 5.7 and my father's 98 Chevy suburban k2500 7.4L the coolant temp sensor went bad but were not setting codes until they completely failed but prior to light coming on they had an extended crank time to restart. If either of these two issues are the problem hold the accelerator pedal to the floor at wide open throttle then turn the ignition on and this will give you what GM refers to ass clear flood and will cut off all fuel to engine and if engine starts up without delay then check coolant temp sensor volts and leave fuel pressure gauge connected and after key on engine off and let truck truck sit and see if pressure drops also crimp the return line so nothing leaks back to gas tank.

Thank you for the insight! If you check a few posts back, I solved the issue by swapping the brake light switch. I have been driving the truck for a few days and have not been able to get it to die again. Before the replacement switch, it was dying every time I took it out, sometimes when first backing down my driveway.

 

[blackburb]

Drove it all around today... didn’t die. I think we have a fix here...

Automatic transmission, truck randomly dies, in gear, with brake applied, at very low speeds (coming to a stop), fuel pressure is maintained when it dies, idles and runs great, no vacuum leaks, does not die when in neutral or park and the brakes are applied.

Brake light switch!

Sounds like you got it fixed. I just wanted to share that I had a very similar issue with all the same symptoms except my shift interlock was not clicking and I had an additional symptom, the engine would shut down while driving... no code. This went on for some time, GM tech finally found the Crank Position Sensor harness was shorting to the block. A little heat shrink tubing and it's been reliable for the last 200k++

 

[Jared Jackson]

Sounds like you got it fixed. I just wanted to share that I had a very similar issue with all the same symptoms except my shift interlock was not clicking and I had an additional symptom, the engine would shut down while driving... no code. This went on for some time, GM tech finally found the Crank Position Sensor harness was shorting to the block. A little heat shrink tubing and it's been reliable for the last 200k++

Troubleshooting these issues can be a daunting task sometimes... I am glad you found your source! Nothing like driving a vehicle that randomly dies! I loved losing my assisted steering and brakes right in the middle of negotiating a turn at a 4 way. I am just glad I never ran into an issue where I was in danger of causing a collision.

I saw a test in another post that I tried today (with my good switch) and it was successful. To make sure the brake switch unlocks the TC, you keep your right foot on the gas at interstate speeds and barely touch the brake. You will hear a change in the exhaust tone as the converter unlocks. I didn't even think of doing that!

 

[east302]

Switch is in! Shift interlock doesn’t click like crazy anymore... so hopefully I will get the seat in quick and test it.

You know, my Tahoe has been acting like this lately. Engine speed drops just enough in reverse and at stops to fluctuate the volt gauge, dim the lights and slow the blower down. The shift interlock switch is loud as hell and I think I can hear it lightly clicking when I first start and drive it. Did yours do that?



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[Jared Jackson]

You know, my Tahoe has been acting like this lately. Engine speed drops just enough in reverse and at stops to fluctuate the volt gauge, dim the lights and slow the blower down. The shift interlock switch is loud as hell and I think I can hear it lightly clicking when I first start and drive it. Did yours do that?



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Not that I can recall... It didn't give any kind of fluctuation, it would just die quickly before the truck was even fully stopped.