Jump to content

08 Yukon No Start Issue

jtupper

Recommended Posts

jtupper Enthusiast

jtupper

Posted
Posted

Wife was shopping yesterday and her car wouldn't start. We had it towed home and checked codes. It's throwing P023F and P069E. Both are fuel pump related. before throwing parts at it I decided to test some things and I found that the fuel pump relay is not getting power from the computer.

 

I'm getting constant power to pin 30 and constant ground to pin 85, but at key on or crank there is no power to the other side of the relay. Now I'm thinking ECM but I'm not sure how to test for it..

sefiroxx Enthusiast

sefiroxx

Posted
Posted

Does it turn over? And get spark? . . Then there is a pretty good working electrical no system . . If not, check the front side electrical first.

 

You can bypass the relay (pull it, and put a spaded wire into the socket - check socket wiring first.

 

If this works, then check wiring from ecm to relay before condemning the ecm.

 

Sent from my XT1053 using Tapatalk

jtupper Enthusiast

jtupper

Posted
  • Author
Posted

Does it turn over? And get spark? . . Then there is a pretty good working electrical no system . . If not, check the front side electrical first.

 

You can bypass the relay (pull it, and put a spaded wire into the socket - check socket wiring first.

 

If this works, then check wiring from ecm to relay before condemning the ecm.

 

Sent from my XT1053 using Tapatalk

Yes, it turns over. I would assume it gets spark. pressure reads zero at the fuel rail.

 

I thought about jumping the relay but not sure which socket to jump to. I would assume pin 87 but afraid that I might fry something if wrong.

jtupper Enthusiast

jtupper

Posted
  • Author
Posted

Well, I jumped the two pins and it still wouldn't start. I'm confused now.

 

As I understand it, when the key is set to on, the computer senses this and sends a signal to the fuel pump to run for 2 seconds to pressurize the fuel rail for starting. Once the key is set to crank/run, the fuel pump stays on. So, when I turn the key to on, I should get power to pin 86 which will close the contact and get power to pin 87.

sefiroxx Enthusiast

sefiroxx

Posted
Posted

Hhmm, now chasing two things.

1) need to check fuel pressure, could be pump or filter.

2) need to check spark and sensor connections.

 

Have you tried to pull codes to see if any history set that might clue in?

 

Yes, the relay has a coil in it attached to the switch.The coil is energized via 86, pulling the switch closed allowing power to flow from 30 to 87.

 

Sent from my XT1053 using Tapatalk

Coby7 Senior Enthusiast

Coby7

Posted
Posted

Hope you checked the fuel pump fuse.... sometimes the fuse may test good on the top test points but may have corroded tabs. Pull the fuel pump fuse and flip it 180° and try it again.

jtupper Enthusiast

jtupper

Posted
  • Author
Posted

Appreciate the responses so far. I dropped the tank today and learned a couple of things about this vehicle. I will explain these so anyone else searching for this might save themselves some time.

 

First of all, even though there is a relay clearly marked fuel pump in the distribution panel, it is not used on this vehicle. It has a fuel system control module mounted on a crossbar at the front of the tank. I spent an entire day chasing a problem that didn't exist.

 

The other thing...since the fuel system is controlled by the FSCM, the fuel pump does not fire up for 2 seconds at key on to pressurize the fuel rail. After dropping the tank I spent a couple of hours trying to figure out why I was not getting power to the fuel pump at key on. Finally, on a whim, I had my son try to crank it and the test light lit up. The real bitch of it all was the damn thing started. My assumption is that jostling the fuel tank around made the pump start working again. Either way, I'm putting a new pump in it tomorrow. I'll be damned if I'm going to put it all back together just to lay down on me again in a day or a week.

 

So there you have it. My gut initially said fuel pump. The DTC codes said fuel pump. My wanting to test some things first ended up costing me two days of frustration and wasted time. I should have her back on the road tomorrow. Could be worse I guess.

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Latest Articles

  • Posts

    • Chuck FB
      2 speed transfer case optional now?

      By Chuck FB · Posted

      Yes, and also pulling heavy trailers or a large camper up steep grades as well as descending grades such as the more rustic off road camping locations and using engine braking with that low gearing as well as soft ground can just suck the power . I realize pickups these days tend to have an over all lower first gear ratio compared to automatic transmission pickups from years back so that has helped a lot in its ability in high range but there comes a point if in four wheel drive the torque runs out at the wheels, certainly with a gas engine. They don't put two speed transfer cases on pickups for a cool factor, they have a function if one needs that massive torque to the wheels that high range can't deliver. 
    • Grumpy Bear
      Grumpy Bears 2015 Silverado 2WD

      By Grumpy Bear · Posted

      Notes 7/18/2026   3,400 miles on this batch of Mobil 1 Euro 5W40 since the GDI pump replacement. Alcohol runs very clean when ring seal is tight and the sump isn't getting hosed with fuel. Checked oil level at fill up today as is my practice and grabbed a white Kleenex to look at the color. What color?  I was going to change it but.....  
    • Another JR
      2 speed transfer case optional now?

      By Another JR · Posted

      4 low is really nice on steep boat ramps. 
    • Chuck FB
      Gas Prices

      By Chuck FB · Posted

      Interesting, I suspect I would have fueled up in Lee Vining as the day prior I would have filled up either in Laughlin or near there and maybe again before I entered Death Valley and once out the other side late that evening as I kept on driving into the night up near Lee Vining. Next morning I most likely fueled up in LV before heading over Tioga Pass into ( as I refer to it as "Yose .... Mite" 😁 ). And again that was 19 years ago but the price then must not have jumped out at me like the 5 bill a gallon theme of nutty cult hippy country Big Sir or head so far up their rear Aspen. I'd be curious to know where the highest prices are in the lower 48, I probably would not be far off to guess somewhere in Cali forn ie. Coldfoot and Prudhoe bay may have those prices beat but that is a whole other world up there and when prices are more normal elsewhere that is about what they can be up there I believe in no mans land. Anyway interesting that the 395 corridor is hosing people and the thing is, its tourist season and its not like there are a lot of competition options when driving up that highway from what I could see. Yup, big ole Boaterhomes and various other RV's ahead and behind me at the Yosemite entrance gate and they have to get their fuel somewhere.  
    • Atlas
      Gas Prices

      By Atlas · Posted

      Those can be high, as well as the big California cities. The ones that will pop your eyes out are the 395 corridor on the Eastern side of the Sierra Nevadas. Lee Vining, $7.19 for regular and $8.89 for diesel is what the Google said right now.

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...