I have a 2002 LS 4 dr 2wd with 75000 miles, the original pump went out and we put in a new pump, everything was working great for about 2 months.... drove the truck and parked it, went to start it up and it ran for maybe 2 sec and shut off and would just crank and not start....got it towed home and was listening for the pump to come on when the key was turned, no noise... so we removed the pump and exchanged it for another one, thinking it went bad... hooked up the new pump, still will not work... Replaced the oil pressure switch, cap and rotor, have power going to the gray wire at the plug on the fuel pump,the relay is fine.... what could the problem be???????? also,the check engine light stays on.... PLEASE HELP ME.........

 

Are you getting both power & ground to the fuel pump? THIS POST should help you with identification of the appropriate wires.

What brand of pump are you installing?

 

Thanks for answering...... It is an Airtex pump......( I know, not the best) when we were checking for power with the test light, there was just power on the gray wire when the key was turned on....... This is probably a dumb question, but how do you check for ground on the plug? Also, will a bad ground cause the check engine light to stay on?

 

You can hook the ground strap of the test light up to a known good +12V source & then probe your grounds. It should light up just like it did with the clamp on a known good ground.

If you have both power & ground to the pump, then that just leaves the pump.

 

Thanks, I will try that........

I believe that is what the problem is going to be ( I hope so)..... I dont THINK the pump would be bad, because it is brand new, but then again.....

Now if the ground is good, and there is not anything wrong with the pump, what else do you think it could be, ignition control module? Ignition switch?

I really do appreciate the help that you are giving me with this issue...

 

If you have +12V to the gray wire & a good ground to both the black wires and the pump still doesn't run, then the pump is the faulty component.

 

Thanks again....

I will let you know what I find out....

Again, I really appreciate you helping me out with this....

 

Just a little advice. Dont start guess what is wrong, Follow Swartlkk's advice.....Guessing is expensive. Troubleshooting isnt. By the way - Ignition control module wont cause this. Ignition switch could but I highly doubt it. Very easy to check. Do you have a wiring diagram for your year of truck? I suggest getting one and learning how to read it. Its your road map to most electrical problems. Also, run to Walmart and get a $10 multimeter and learn how to use it. The more you use it the more reasons you will find to use it.

GOOD LUCK!

 

But a 12v test light is better for power circuits. Unless you get one of the old style needle type meters.
Problem being a bad connection can still show 12 volt -or grd- without current flowing.

 

Personally I wont use my simpson analog meter or a test light on a computer controlled vehicle. The high impedence in a digital meter makes it safe to probe the low voltage wires use in the computer. Hook a test light to the wrong wire in the wiring harness and you just injected 12 into a 5 volt circuit. That lets the magic smoke out.

Ive always had a problem telling if i have 12 volts or ten volts by the brightness of the bulb! LOL

Most of the time you might be lucky and it never happens to you. But I know how my luck goes.

Is $10 bucks really too much to pay for a tool that cost THOUSANDS 45 years ago?