01 8.1 Burb Dead

[AP Guy]

Hey all,  first time post so hopefully this is in the right section.   

 

Hopped in my 01 Burb this weekend and I got about 2 miles down the road and it shut off on me while cruising about 60mph.  Low fuel light came on and its shows empty but I know there's fuel in the tank. Engine turns over but won't fire or pop or anything. No fuel pump noise when I turn the key and no fuel rail pressure either so my original thought was my fuel pump went out, but after further instigating it sounds like the crank sensors on these 8.1's are prone to failure and also control the fuel pump. Security light was flashing as well so could it be something funky with the passlock system?  

 

My question is will I still hear the pump prime with a bad crank sensor or does it kill the pump entirely?  If it does that makes sense why it's showing empty since it's not getting power. 

 

The weekend before I decided to pull my RTD fuse in an attempt to clear my service ride control dic light(installed Bilsteins) and had the ecu disconnected for a while.   This was my first time out since then so could something have failed a learn?  But if that's the case why can I not restart it. Won't fire up at all. 

 

Thanks for any help. Suburban is an 01' 2500 w/ 130k miles. 8.1 Vortec. 

[Black02Silverado]

Considering the year I would guess it is the fuel pump.  You should be able to hear it when you turn the key on.  I don't think the crank sensor comes into play for that.  How many miles on it?

[AP Guy]

Has just over 130k on it.  I've noticed a whine  for quite a while that you can hear from the outside coming from the pump when the truck is idling.  Maybe that was its warning call. 

[AP Guy]

Been investigating a bit more and have come across a few issues of others having some faulty wiring/connectors below the underhood fuse block that may cause a crank but no start issue.  I was just about ready to get a crank sensor coming but I'm not 100% convinced it's the sensor, and not 100% convinced it's the actual fuel pump...yet.  Just odd to me the gauge is reading empty, doesn't even blip when you turn the key on like it's not getting power.  No check engine lights.  Been busy with other irons in the fire but I will try and see what the scanner says and hopefully there is some latched codes in there that may point me in the right direction.

 

Does anyone know if there is a known issue with the fuse blocks on the GMT800 trucks?

[Colossus]

no not that I know of.. I'm betting it's the fuel sender there in the tank.  Replace the whole module.  (fuel pump and fuel level sensor)  You'll be glad you did.  Very common issue on the GMT-800s though usually with the 4.3, 4.8, and 5.3L.  Can't recall anyone with the 454 reporting this, but at your millage, the fuel pump would be weak anyway.  The fuel pumps on those older GMs were always noisy, even when they were good. 

[AP Guy]

Been a bit busy lately so I havent dropped the tank yet but I'm wondering if the auxiliary tank pump were to fail and the primary pump sucks the tank dry would the primary pump still try to prime with a turn of the key or is there a safety to keep it from running when the tank is "completely" empty. 

 

I guess I'll find out if I drop the tank and its empty since its supposed to have close to 1/2 in it. 

[AP Guy]

Now that the family vacation is done I was able to tinker with the burb a bit tonight.  I jumped over the relay and the pump does turn on.  I haven't pressure checked it yet but that doesn't explain why it's not turning on with the ignition switch.  So I'm back to square one.

 

Does anyone have a wiring schematic on these heavy burbs? Just wondering if there's something I'm missing in the fuel pump circuit.  Still wondering about crank sensor.  Maybe the ignition switch? Passlock?  I'm scratching my head on this one.

[davester]

I would suggest signing up for the full-service manual at alldatadiy.com or helminc.com (or other sites).  It'll have the complete wiring diagram, pinouts of connectors, where ground and power connections are, as well as diagnostic procedures (which may require the use of specialized tools or a tech ii or something similar).

 

Totally worth it if you want to work on or diagnose problems with your vehicle.

[AP Guy]

I thought I double checked all the fuses but I decided to look through them one last time and found the ECM-B fuse blown. Replaced it and viola!  Fired right up. 

 

So...it had to blow for a reason.   Wondering if fuel pump is drawing too much amps?