1999 Yukon, No Power To Fuel Pump

notyepcars · June 27, 2009

1999 Yukon, died while going down the road, towed in, replaced fuel pump, still does not

Hum or run when the key is turn on. I also do not have power to any of the 4 pins

in the plug that snaps on the pump. Fuel pump relay clicks when key is turn on. If I pull the

relay, I have power to 1 of the posts. Does the pump relay run thru the oil pressure

switch? Or what else can I check. My brother has a 96 GMC, swapped fuel pump relay

with no change. Any ideas? Thanks

bill190 · June 27, 2009

Look in your owner's manual for fuses. Then check the associated fuses. If that does not work, check all fuses.

How to check fuses...

http://www.dinosaurelectronics.com/Test_Fuse.htm

notyepcars · June 28, 2009

Hello,

I

Look in your owner's manual for fuses. Then check the associated fuses. If that does not work, check all fuses.

How to check fuses...

http://www.dinosaurelectronics.com/Test_Fuse.htm

I have checked all fuses in the panel under hood and the other inside the door,

Everything looks good.

bill190 · June 28, 2009

If the fuel pump relay in the engine compartment is clicking when the fuel pump should be coming on, but you have power to only one connection to that relay, and that connection is to the relay "coil", then you do not have power from the fuse block to the relay contacts.

Following is a relay diagram. This is probably not exactly like your relay. But on the left is an electromagnetic coil. When electricity flows through the two wires for the coil, it acts like a magnet and makes the little lever move over. This is the click sound you hear.

When the lever moves, it makes an electrical connection on the right side.

The electricity to power your relay coil would come from one fuse. And the power for the contact/switch (which would go to power the fuel pump) would come from another fuse. So if you do not have power to that contact, then there is a blown fuse or a wiring problem between the fuel pump fuse and that relay contact connection.

ss502gmc · June 28, 2009

I had this problem on another truck and found out after it being dead for a couple weeks that there was a small break in one of the ground wires on top of the fuel tank that was causing the pump to ground out and when i mean small break i mean like the size of a pencil lead. " found that after putting 2 different pumps in when the original was fine "

Good Luck