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Shut off while driving.

N

NinetyEightGTP

New member
Was driving along, getting on it a little bit maybe 75% throttle, and then it just cuts out with a nice little backfire (I'm assuming from it having cut out at like 4 grand) and then that was it. Tried to go and put some gas in it thinking the gauge might be wrong, but it just turns over. Didn't sound mechanical like I snapped the chain or dropped a rod or anything.

At this point I don't have any ideas. Where do I start?
 


Well one likely thing to cause that is the crank sensor. There are many others but this is the easiest place to start. Do the rpm's go to 200 or so when cranking? It should. Next your fuel pump may have just died. Do you have fuel pressure? press the schrader valve on the rail and see if fuel squirts out.
 
Yeah it's a good bet. They usually start working once it cols off temporarily, but I guess some can just flat out stop working. Like my starter, most you can hit them and get them to work for a while, but mine left me stranded with hitting it doing nothing.

To be sure its not the computer or the wiring you can unplug the connector and hook an led up and see if it flashes when you crank it, but it's probably the sensor anyway.
 


When they go bad, they will almost always be intermittent (like I said before) so the crank sensor is still the likely cause. Now that it's working, does the tach go to 200 when cranking? It might start too quick to tell though.
 
My car stalled several times while I was driving due to bad CPS. I think there was up to a week between stalls even. My tach would also just stop giving a reading sometimes while cruising and go to 0 until I stopped and restarted the car. Replaced it with a ~$34 CPS off amazon and was fixed!
 
02NavyBlue said:
When they go bad, they will almost always be intermittent (like I said before) so the crank sensor is still the likely cause. Now that it's working, does the tach go to 200 when cranking? It might start too quick to tell though.
Click to expand...

Unfortunately, my car is too healthy and she starts on the first crank, so I can't really tell.
 
Well I was just wondering because it could be a way to show you what I mean. Doesn't matter though. I bet it's the cps

Here's an example of the tach going to 200 on a cold morning it took a bit to start. Usually it starts quickly and I don't see it. But as a reference:

 
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I can leave mine for weeks in the freezing cold and it starts up like I had it running an hour ago. Ever since I rebuilt the top end it's been super reliable and stupid fast. This has been my only major issue. That said, I've got a new CKP sitting on my desk and I'm going to swap it in this weekend.
 


Right, the sensor just transmits crankshaft speed and position. It doesn't affect how well it runs, just whether it does or doesn't. Good luck with the install. The video was from a few weeks period I was having an extended cranking time due to a possibly bad fuel pressure regulator. It's back to starting in a normal amount of time.
 
02NavyBlue said:
Right, the sensor just transmits crankshaft speed and position. It doesn't affect how well it runs, just whether it does or doesn't. Good luck with the install. The video was from a few weeks period I was having an extended cranking time due to a possibly bad fuel pressure regulator. It's back to starting in a normal amount of time.
Click to expand...

Yep, I'm well aware of what the sensor does. I'm just surprised it went out on me.
 
Well..don't be lol. It's a common 3800 thing, well many GM platforms for that matter. I'm going to change mine as a precaution because I know it will go bad eventually, and leave me stranded somewhere.
 
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