Crankshaft Position Sensor Keeps Going Bad Causing Stalling?

[Timbers]

Hi everyone, this is my first post, hope to help others while I am here, but I came here to ask your collective knowledge.

My 2000 Yukon Denali 5.7 with 223,000 miles, had a random stalling issue, would stall at a stop, would stall accelerating and would stall while crusing at 70MPH, causing me to shift into neutral and restart the car. I threw a pressure gauge on it once and had 0PSI, meaning something shut the fuel pump off.

This happened before and after I installed a new fuel pump (because of bad sending unit) so I know thats not the problem.

I replaced the crankshaft position sensor with an AC Delco one from Amazon, and the truck ran like new for about 1700 miles. In the past it never made it more than 100 miles without stalling. Today it started stalling again, 5 times actually.

Have any of you had crankshaft position sensors go bad over and over? When I get home I will check it for physical damage, maybe a worn crankshaft is hitting it and damaging it? I'll also re-check the wire harness and connector. I may also rotate the engine to find the magnet to make sure there isn't any metal shavings stuck to it.

Just wondering if any of you have had a similar situation.

 

[RET423]

If it was a failure of the crankshaft position sensor it would have a code stored revealing that, if it does not have a code stored I would start by checking your key cylinder and housing for signs of slop/wear and also your fuel pressure.

You would not be the first to have a new fuel pump die prematurely.

 

[M1Gunner]

A bad crank sensor wouldn’t kill the pump. A bad ckp sensor kill injectors and spark to the engine.

Did you perform Ckp variation relearn procedure after playing with that sensor?

 

[M1Gunner]

Also, what were the conditions when the fuel pressure gauge read zero?

 

[Timbers]

Thanks for the replies. I was driving slow about 25mph and the car shut off. I pulled over and didn't even shift out of drive, I jumped out and put the pressure gauge on the rail and there was no pressure. I cycled the key and the pump came back on and went right back up to 60PSI.

I didn't do a re-learn procedure, I didn't know that this vehicle needed that. Does anyone have directions?

It was doing it before the pump was replaced though. And its been flawless for over a month now, since the day I replaced the CKP.

 

[M1Gunner]

Keep the gauge installed. Key on engine off notate the pressure after three cycles and if the pressure stays steady.

 

[Timbers]

I feel like an idiot but it had nothing to do with the crank position sensor. It was the fuel pump relay. When I replaced the crankshaft position sensor I also pulled the relay out and noticed pin 87 was tarnished, so I cleaned it up with my knife and put it back in. That was what the problem was because a month later it started stalling out on me again, with zero fuel pressure after the stall.

I noticed when I removed it the other day that the plastic around pin 87 was also melted. I'm assuming the old fuel pump I just replaced was drawing a ton of current and caused that pin to heat up.

I replaced the fuel pump relay on Monday and have about 350 miles on it without a hiccup.

Glad its fixed. I think I learned from this whole ordeal:

1. Never attempt two fixes at once, unless you are in a hurry!
2. Even if the crank sensor dropped offline, the fuel pressure would still remain because the PCM would shut off the injectors, spark, and fuel pump, and the remaining pressure would just sit in the system.
3. After changing out a fuel pump its probably a good idea to throw a $9 relay at it too. The relays don't live forever, and chances are a bad or failing pump may have cooked up the relay too....

 

[6speedblazer]

i was going to comment bad fuel pump relay. I rewired a TON of fuse boxes on the 96-00 vortec motors. i would remote mount a gm 40 amp weather pack relay on the fender.

but yes, the root cause is the pump drawing too much current and buring out the wiring, relay, or contacts.