Crank sensor went? Changed and now won't start

EfiniMotorsport · Aug 10, 2019

My truck died getting off the highway a few days ago. I was driving along and heard a few small back fires then lost all power. I managed to get off the highway and have the truck towed home. It would start but wouldn't even get up to idle speed then died in a second or two. I've been having a slight misfire for a while now and got a flashing check engine light and p0300 code last weekend. I changed the crank position sensor and now the truck won't even start, just cranks. I can hear the fuel pump priming so I'm pretty sure that's not the issue. Unfortunately I'm not sure what is aside from the wrong crank sensor. Anyone have any other ideas?

SnowDrifter · Aug 11, 2019

Verify for me:

Diag'd bad crank sensor, replaced, truck worse off now?

Scope the sensor to see if its bad, else just toss a new one in. Oh and make sure the plug is seated all the way

mikeyss · Aug 11, 2019

I think there is a relearn procedure for that sensor once you replace it. I'm not 100% sure on that though.

EfiniMotorsport · Aug 11, 2019

Truck needs to be running to do the relearn

EfiniMotorsport · Aug 11, 2019

I ordered another sensor. Hopefully the new one works. I'll ha e it Monday.

mattbta · Aug 12, 2019

mikeyss said:
I think there is a relearn procedure for that sensor once you replace it. I'm not 100% sure on that though.

There is. I replaced mine chasing an oil leak and didn't need a relearn but I read that instances might necessitate the relearn. I think it was a tech2 type relearn.

EfiniMotorsport · Aug 13, 2019

New one didn't work either. I can hear the pump priming but have no fuel pressure. Going to swap the pump next.

SnowDrifter · Aug 14, 2019

Let's rewind a second.

Sounds like we're missing something

What all did you do for diag? And what's the info on your truck? Mainly engine and year is what I'm looking to know

EfiniMotorsport · Aug 14, 2019

Truck is an 04 Denali. I was driving on the highway and felt a few small backfires in the exhaust then lost all power. Got off the highway and truck died and would only restart for a second. Didn't think to check for fuel at the time. I've had a slight miss occasionally for a while and had a p0300 code pop up. I know it had to be fuel or spark issue and a crank sensor will prevent it from starting so I changed it. Still won't start. I ordered it through Amazon so free return. I can hear the fuel pump turn on with the key but I have no pressure at the fuel rail

Kraig · Aug 14, 2019

If there’s no fuel pressure at the rail with the key on, you have a fuel problem. You might try banging on the tank and see if the pump will come on one last time, then change the pump, or troubleshoot the wiring and make sure itMs getting power when it’s supposed to.

Crank sensor went? Changed and now won't start

EfiniMotorsport

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