2002 Yukon no power to fuel pump

[myoldmetal]

I have a 2002 Yukon which decided not so start after being parked for a few days. pump wasnt priming and relay was working, so I assumed pump. had it towed home, and decided to remove the relay for inspection. It looked ok, so I put it back in and the truck started. With 160k, I decided to change the pump anyway, so I bought a pump (with new harness), filter and relay. Changed all these items, and now the truck wont start. Relay clicks, all fuses are good and all wiring connections are good. No power to any wires at the pump. low fuel light is on, gas gauge not working, and pump has no power so it wont prime. Can anyone help??

[truckdude239]

sound like the wiring harness isn't right. i jsut put a fuel pump in my boss 88 s-10 blazer and the new harness was wrong. i would look at the harness where did you buy it at so far only the dealer pumps and harness have been the only ones i seen hold up. where an after market pump i've replaced 3 in one truck ina year before going tot he dealer and getting the dealer pump

[UltraBlue71]

Did you get this fixed? Wow what a weird problem... Stay away from the cheap pumps unless you really like changing them, I had a NAPA one that worked well..

[myoldmetal]

Originally Posted by UltraBlue71

Did you get this fixed? Wow what a weird problem... Stay away from the cheap pumps unless you really like changing them, I had a NAPA one that worked well..

no this isnt fixed. It is a NAPA pump ($268) and I did replace with the upgraded harness. I thought at first that the pump was no good, but the truck is not even sending power to any of the wires at the pump. Im not sure what else to do with it....I guess Im gonna have to send jumper wires to the pump and see if it comes on that way

[lyrikz]

Originally Posted by myoldmetal

no this isnt fixed. It is a NAPA pump ($268) and I did replace with the upgraded harness. I thought at first that the pump was no good, but the truck is not even sending power to any of the wires at the pump. Im not sure what else to do with it....I guess Im gonna have to send jumper wires to the pump and see if it comes on that way

At my shop, i never run napa anything. Especially something that is kinda a pain to replace like that fuel pump. GM AC delco is the only way to go. I have installed bad pumps out of the box from napa.

What i recommend doing is replacing the relay with a known good one. Then just do a shake test on the wiring. We had some rigs up here that had shorted harnesses from the fuel pump. You just have to find that short.

[clinebarger]

Heres some diagrams and a connector veiw



CIRCUIT DESCRIPTION
When you turn ON the ignition switch, the control module enables the fuel pump relay which powers the fuel pump ON. The fuel pump remains ON as long as the engine is cranking or running and the control module receives ignition reference pulses. If there are no ignition reference pulses, the control module shuts the fuel pump OFF within 2 seconds after the ignition was switched to the ON position or if the engine stops.

[myoldmetal]

The problem isnt the Napa pump. The problem is the the truck is not sending power to the pump. I have swapped the relay, and done the wire shake. in fact, I removed the under hood fuse box so I could inspect the plugs and ECU, and also traced the harness under the entire truck.....still no signal to the pump.
Thanks for the diagrams clinebarger. I was able to get a hold of these when I dropped the tank the second time, and I held the test light on the wiring while someone else turned the key on to make sure I csught it within the 2 seconds.......nothing. next I will be unplugging one of the injectors to see if I have a pulse at that loction, and see if I can narrow it down from the other direction.

[lyrikz]

Originally Posted by myoldmetal

The problem isnt the Napa pump. The problem is the the truck is not sending power to the pump. I have swapped the relay, and done the wire shake. in fact, I removed the under hood fuse box so I could inspect the plugs and ECU, and also traced the harness under the entire truck.....still no signal to the pump.
Thanks for the diagrams clinebarger. I was able to get a hold of these when I dropped the tank the second time, and I held the test light on the wiring while someone else turned the key on to make sure I csught it within the 2 seconds.......nothing. next I will be unplugging one of the injectors to see if I have a pulse at that loction, and see if I can narrow it down from the other direction.

Sounds like an interesting one. Can you test for signal on whatever device it is thats supposed to tell the pump to be on???

I know the napa pump isnt the problem now, but what im saying is it will be later. On average its about 15 months before we see the customer again with fueling issues. Thats why we stopped using them.

[lyrikz]

Originally Posted by clinebarger

Heres some diagrams and a connector veiw



CIRCUIT DESCRIPTION
When you turn ON the ignition switch, the control module enables the fuel pump relay which powers the fuel pump ON. The fuel pump remains ON as long as the engine is cranking or running and the control module receives ignition reference pulses. If there are no ignition reference pulses, the control module shuts the fuel pump OFF within 2 seconds after the ignition was switched to the ON position or if the engine stops.

Oh, and my guess is a bad ground somewhere. Unless you shorted something installing the new harness.

[myoldmetal]

Im trying to trace the entire harness from the pump up to the fuse block now to see what show ignition power and what doesnt so I can narrow it down.
No I didnt shrot anything when I wired in the harness.....the battery was disconnected during that time, and the harness is wired color to color, with splices taped and installed in conduit as they should be. im still pretty stumped with this one, so hopefully I can trace the problem to another plug or component

[bighaas79]

Unless I missed it I didn't see that you checked to see if you had power at the correct terminals in the fuse block for the fuel pump relay. It clicks is not a good enuf test. That means the control circuit might be working properly but doesn't mean the power circuit is live or the relay is making contact inside. Try jumping the relay terminal in the fuse block for the fuel pump power feed to the fuel pump with a jumper to the positive bat terrminal. Then check to see if you are getting power to the pump. If you are it is a problem in the power feed to the relay if you aren't then you have an open or short to ground in the harness between the relay and the pump. Check fuses too, don't make it harder than it needs to be.

[STOCKISH]

Originally Posted by clinebarger

Heres some diagrams and a connector veiw



CIRCUIT DESCRIPTION
When you turn ON the ignition switch, the control module enables the fuel pump relay which powers the fuel pump ON. The fuel pump remains ON as long as the engine is cranking or running and the control module receives ignition reference pulses. If there are no ignition reference pulses, the control module shuts the fuel pump OFF within 2 seconds after the ignition was switched to the ON position or if the engine stops.

If you supply power to pin B on this connector will the truck run? Have seen this grey wire broken near the fuel pimp on 3 tahoe's.

[myoldmetal]

Most recently, after not getting continuity on the circuit, I traced the entire harness from the fuse box all the way down to the pump, and found a tiny crack in a grey wire where the harness goes over the trans/transfer case. fixed that and finally got this thing to run!
thanks for the advice everyone

[67ChevyRedneck]

Wow, what a pain! Glad it's going for you again!

[STOCKISH]

Glad it's running for ya.