96 K1500 Burb seems to not be getting fuel. Cranks but wont start. Need advice please

[Nad_Yvalhosert]

I've got power to the grey wire for ~2 seconds when the key is turned to run (for prime).

And I have constant power on purple when key is turned to run

So that means purple is for the fuel level sensor, and gray is pump power.
Do you get power on gray when cranking?

And just to rule out any other issues, does the engine run on starting fluid?

 

[Caman96]

So that means purple is for the fuel level sensor, and gray is pump power.
Do you get power on gray when cranking?

And just to rule out any other issues, does the engine run on starting fluid?

…and do you hear pump priming? I’d still cross reference test to see if old pump spins up on bench.

 

[8thNote]

…and do you hear pump priming? I’d still cross reference test to see if old pump spins up on bench.

So that means purple is for the fuel level sensor, and gray is pump power.
Do you get power on gray when cranking?

And just to rule out any other issues, does the engine run on starting fluid?

Yes, there is power on grey when cranking

I do not here pump priming. It will not come on at all. But I have verified that there is power on grey wire for 2 sec when key is turned to run, and there is power on grey wire when cranking

The only thing that I have not been able to verify is if black/white wire in the 3-pin connector is supposed to be a ground

There is a solid black wire that cones off of the fuel pump that bolts to the frame for ground.

 

[Caman96]

I thought:
Grey-power to pump
Black-ground to pump

Purple-power to gauge
BLK/Wht-ground to gauge

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Edit: The purple may actually be the gauge ground and blk/wht go to fuel gauge.

 

[8thNote]

I thought:
Grey-power to pump
Black-ground to pump

Purple-power to gauge
BLK/Wht-ground to gauge

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That's what I thought too, just have not been able to find a direct source to confirm

So that would mean that, if hypothetically the black/white wire was not grounded properly, it would not prevent the pump from working. It would just prevent the gauge from working.


So im at a loss. Maybe the new pump is defective. I do not have the knowledge to bench test it, as it's something I've never done. I guess I'll have to learn.

I'm 100% self taught when it comes to wrenching. Just common sense, YouTube, and this forum. I've never had any training, formal or otherwise.

 

[Caman96]

Run 12v and ground directly to fuel pump. It should kick on if it’s good. If it doesn’t, then no good. Your old one I’m talking about. Disconnect truck battery. Then use a couple of wire jumpers from battery to test.

 

[8thNote]

Run 12v and ground directly to fuel pump. It should kick on if it’s good. If it doesn’t, then no good.

Sounds easy enough. I'll try it one day this week and report back. Thanks !!

 

[8thNote]

Finally got the Suburban running. The new fuel pump/sending unit that I bought was defective. I ended up buying just a pump and swapped it into my old sending unit because I discovered that, for folks with Suburban and Tahoe, the sending units are differently shaped than pickup sending units. The gas tanks are different shapes (Suburban tanks are more square, pickup tanks are rectangular)

In a Suburban/Tahoe the fuel lines coming out of the sending unit are perfectly horizontal. On pickups, they curve downward at about 45°. Also, the overall height of the unit is shorter than a pickup unit. The two are not interchangeable without modifications and most places will sell you the pickup unit even if you specify that it's for a Suburban/Tahoe.

Suburban/Tahoe:

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Pickup:

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[HotWheelsBurban]

Finally got the Suburban running. The new fuel pump/sending unit that I bought was defective. I ended up buying just a pump and swapped it into my old sending unit because I discovered that, for folks with Suburban and Tahoe, the sending units are differently shaped than pickup sending units. The gas tanks are different shapes (Suburban tanks are more square, pickup tanks are rectangular)

In a Suburban/Tahoe the fuel lines coming out of the sending unit are perfectly horizontal. On pickups, they curve downward at about 45°. Also, the overall height of the unit is shorter than a pickup unit. The two are not interchangeable without modifications and most places will sell you the pickup unit even if you specify that it's for a Suburban/Tahoe.

Suburban/Tahoe:

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Pickup:

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Good to know, since I have one of each!