2006 6.0 Cranks but won't run after new oil pressure switch installed

[BanoChris]

Hey all,

I have a 2006 Silverado HD with a 6.0 Vortec. When I bought the truck I was told it needed a new oil pump because there was very low oil pressure. It ran, but the lifters ticked. It was delivered on a tow truck and I only cranked it once to back it into the shop. So I put in a new Melling oil pump, water pump, belts, filter, oil pan gasket and all the appropriate seals and gaskets. After I primed the oil pump, the truck started right up but still had low oil pressure. So I took out the oil pressure sensor and hooked up my oil pressure gauge, that was a fun time getting back there. Then the truck would turn over but not run. Grrr. So I disconnected the oil pressure gauge and reinstalled the oil pressure sensor and it still won't run. It turns over, but will not run. I disconnected the battery for 24 hours but that had no affect. Is there something back by the oil pressure sensor that I may have knocked lose? There is fuel pressure. I have no idea where to start troubleshooting.

[Black02Silverado]

is it a new sensor or the original one?  If it is a new sensor it could be bad.  It happens.  Otherwise, since you have fuel pressure, do you have spark? 

[BanoChris]

Thanks Nick.

 

It's the original pressure sensor. I haven't checked for spark yet. I can do that later when I get home.

 

I forgot to mention that I disconnected the wire from the pressure sensor after I had put the oil pressure gauge on. It would not run. Is there a relay that checks the oil pressure and turns on the fuel pump if there's oil pressure?

 

Also not getting any Error codes with my Innova.

I checked all the fuses in the fuse box behind the battery. Is there another fuse box?

[Mike GMC]

Yes, there is an oil pressure lockout for the fuel pump.  If there is no pressure, the pump won't run.  Also, the sensor is right next to the can position sensor, you didn't accidentally disconnect get did you?

[Mike GMC]

Cycle the key to ON without starting and listen for the pump to run.  It will only run for a few seconds without the engine running.

[BanoChris]

Is the Crankshaft PS on the front right of the block and the Camshaft PS on the back? If they where hosed or disconnected shouldn't I be getting a P code? I'll double check all the connections I can find. I'll also listen for the pump to prime. I'm assuming the lockout is part of the relay, Is there a way to test it?

 

I sprayed a little "Engine Start" in the throttle body and it chugged, so it sounds like I have spark.

 

 

[BanoChris]

So I did a little research and found a GM VIN Decoder. According to to that decoder I have a 6.0L LS2 engine type. The Crank Shaft sensor is right by the starter and the camshaft sensor is up front just above and to the right of the harmonic balancer. So I'll check those tonight. I'm going to get a fuel pressure tester as well and see what happens. What should the fuel rail pressure be after the pump primes?

 

http://www.chevythunder.com/gen_iv_engine_family.htm

 

[Black02Silverado]

Check all those connections.  The fuel pressure should be 52psi.  You can get a test gauge loaned to you from Auto Zone.  That is where I got mine when I had hard starting issues. Turned out to be a bad fuel pump on my 02 Silverado.  Which is a known issue on the GMT800's.

[BanoChris]

Thanks Nick. It looks like there are several relays that are the same as the fuel pump. I'll try swapping them, but I have a feeling you're probably right. I suppose the best way to replace the pump is to lift the bed..?

[carkhz316]

19 hours ago, Mike GMC said:

Yes, there is an oil pressure lockout for the fuel pump.  If there is no pressure, the pump won't run.  Also, the sensor is right next to the can position sensor, you didn't accidentally disconnect get did you?

Not on these trucks. OP must have bumped or disconnected something else. The oil pressure sensor/ circuit has nothing to do with fuel pump or starting or anything on these trucks. You can literally unplug it while running and it'll do nothing but alter the gauge reading. However, if the wiring was somehow pinched/ shorted, it'll pull that 5 volt ref. to ground killing the other 5V ref circuits for some of the other engine sensors (like the MAP), which will absolutely cause a no-start.

Edited September 5, 2018 by carkhz316

[BanoChris]

Well that's good to know... I'll make sure and check the MAP connection. I was pretty much on top of the engine trying to get to the Oil Pressure Sensor. Even though I was careful, I could have easily pinched or disconnected something. If something was shorted, like the MAP, would I get a code?

[Supreme Pizza]

32 minutes ago, BanoChris said:

If something was shorted, like the MAP, would I get a code?

 

 

If you disconnected the map sensor, it would still run - and it would throw a code. 

 

If yours is a late model 2006, its possible you might have the screen. Probably not, but its worth having a look: 

 

https://noln.net/2017/05/31/low-oil-pressure-message-locating-mystery-filter/

 

 

 

 

[BanoChris]

Is that a screen for the MAP or Oil Pressure Sensor?

[Supreme Pizza]

23 minutes ago, BanoChris said:

Is that a screen for the MAP or Oil Pressure Sensor?

 

 

 

   If you do have the screen, it would be directly below the oil pressure sending unit. It can be removed with a bent coat hanger, or a small hook/pick. They seem to some out easier after your spin then around a couple times. 

[Supreme Pizza]

 

    The screens started in 2007 on the 5.3's, but I think its still worth checking your engine.