1996 chevy fuel pump without power

[bigT5]

i have a 1996 chevy 1500 that the fuel pump seemed to have went out. i drove it to town about 3 miles away came home was home for like 10 minutes then had to go back to town and my truck wouldnt start the i replaced the filter which was was pretty clogged and when i turned the key on no gas came out still so i replaced the fuel pump put it together and still nothing. then i discovered the sound i thought to be the pump was actually coming from under the hood somewhere and i have a tester that lights up when you touch it to power and i have power on one of the 4 prongs on the plug that goes to the fuel pump shouldnt there be 2 of 4?? also i checked the relay and it has power going into it and then after messing with that i ended up with no power to the plug is this becaus of the relay or where do i go from here????

thanks

[MT-2500]

Originally Posted by bigT5

i have a 1996 chevy 1500 that the fuel pump seemed to have went out. i drove it to town about 3 miles away came home was home for like 10 minutes then had to go back to town and my truck wouldnt start the i replaced the filter which was was pretty clogged and when i turned the key on no gas came out still so i replaced the fuel pump put it together and still nothing. then i discovered the sound i thought to be the pump was actually coming from under the hood somewhere and i have a tester that lights up when you touch it to power and i have power on one of the 4 prongs on the plug that goes to the fuel pump shouldnt there be 2 of 4?? also i checked the relay and it has power going into it and then after messing with that i ended up with no power to the plug is this becaus of the relay or where do i go from here????

thanks

Only one wire the gray one should have 12 volt power for pump run.
For fuel pump to run you need power on gray wire from relay to fuel pump.
Just key on only gives pump power for 2 second prime .
Does the gray wire have power key on 2 second prime up or with engine cranking.
Make sure relay has 12 volt power to it.
Power feed to relay is fused.
Always check all fuses on both sides for 12 volt power key on.

[j cAT]

Originally Posted by bigT5

i have a 1996 chevy 1500 that the fuel pump seemed to have went out. i drove it to town about 3 miles away came home was home for like 10 minutes then had to go back to town and my truck wouldnt start the i replaced the filter which was was pretty clogged and when i turned the key on no gas came out still so i replaced the fuel pump put it together and still nothing. then i discovered the sound i thought to be the pump was actually coming from under the hood somewhere and i have a tester that lights up when you touch it to power and i have power on one of the 4 prongs on the plug that goes to the fuel pump shouldnt there be 2 of 4?? also i checked the relay and it has power going into it and then after messing with that i ended up with no power to the plug is this becaus of the relay or where do i go from here????

thanks

using a test light for this type of troubleshooting is not recommended.. get a volt-ohmmeter then find out whats up.. this will save you much money from miss leading test lights..

[Blue Bowtie]

That series of truck has a serious problem with the grounding for the pump. Voltage to the pump is critical since even a few ohms resistance can drop the pump supply voltage enough to prevent adequate fuel pressure to the injectors.

The ground is provided through the pump power connector on top of the tank, then routes through another power connector above and just ahead of the tank, then is grounded at the frame just in front of the LR wheel opening. This ground connection is subject to corrosion from road spray. Around here we started seeing those about four years after the trucks were built due to accelerated corrosion from road salt, lime chips (being used for traction), 30" of rainfall, then freezing and salt again. I would suspect a similar occurrence in Wyoming, and it's worth investigating.

I had one truck whose owner had a shop replace the pump 3 times ('97 Sierra) and asked me to check it out before the fifth pump (fourth replacement) was installed. Yup, connections and grounds.

[bigT5]

ok that does make sense i saw that ground and wondered about it but i didnt do anything with it. and i dont have one of those testers just the light one and i had power to one of the prongs would it still light up with that ground not grounding very good???? and just a note on the one prong that did have power my dad i was running the key my dad was testing he said the light wasnt very bright like the fuses were

[MT-2500]

Gray wire is fuel pump power wire.
Should show 12 volts on volt meter.

Do not confuse it with lower voltage fuel gauge sending unit wire.

Black or black/white is fuel pump ground.
If it has any voltage on it ground is bad.

[bigT5]

ok we had power to a white wire

[bigT5]

also when i turn the key on there is a sound coming from under the hood somewhere not real sure where but what could that be its like a turning or not really a whining sound i dont know how to describe it

[bigT5]

ok this is what i got i checked the little ground on the frame cleaned it tightened it and every thing i have power to two wires a black wire with lots of power and the white one that barely has any power to light the bulb i know i i need one of those testers when i get more time ill see if i can borrow one unless i fix it before then but shouldnt the red and white one have power not a white and black one????

[bigT5]

nevermind i fixed it it was that ground on the frame thanks guys i owe you one

[MT-2500]

Originally Posted by bigT5

ok this is what i got i checked the little ground on the frame cleaned it tightened it and every thing i have power to two wires a black wire with lots of power and the white one that barely has any power to light the bulb i know i i need one of those testers when i get more time ill see if i can borrow one unless i fix it before then but shouldnt the red and white one have power not a white and black one????

White/black is ground wire.
If it has any voltage or lights test light it is not grounded good .
As you found out you have a bad ground.

The gray wire is fuel pump power wire.
It feeds full 12 volts to fuel pump to run fuel pump.
The gray wire is only one that should have 12 volts or light a test light bright.

The other two wires are for fuel gauge sending unit in tank.
And one of them is a ground for it.
The other on has a very low voltage from dash fuel gauge.
But do not even worry about them if fuel gauge is working.


Thank for posting back what you found and the fix on ground.
Good Luck