3 bad fuel pumps in a row, unbelievable!

[Korn]

The relay has a positive voltage output not ground. G404 is the grounding point for your tank pump and is located above the pump on the frame rail. It might just need some cleaning. The frame to battery ground could also cause a voltage drop when using the frame as your ground.

Well I didnt know about the ground wire to frame rail so I just got done running a jumper wire from the black wire on the connector to the chassis. It works I guess, the voltage stayed around the 12.32 area. Still cant figure out why the orginal ground have voltage to it and cause the test light to light up. Now all I have to do is get one of the new pumps back and give it a try. Wonder if this is why I keep getting the codes that says its lean on bank 1 and bank 2. Thanks for all the help guys, I really do appreciate it.

 

[retorq]

My 95 had the ground right there at the tank ... weird that you are getting voltage thru the ground in the harness ... glad you got it fixed. Electrical gremlins suck!!

 

[SunlitComet]

What were the test points you used when you found this .13volts? it is not uncommon to find volt readings such as this around the vehicle. .13volts should not be enough to cause problems.

 

[Korn]

What were the test points you used when you found this .13volts? it is not uncommon to find volt readings such as this around the vehicle. .13volts should not be enough to cause problems.

I used the chassis as the ground and the other wire (red) to the black ground wire going to the pump. Im sure its not enough to cause a problem but by cutting that wire and running it to the chassis it made the voltage to the pump go from 11 to 12 volts. Also by doing this Im not getting voltage and the test light doenst light up when I test between the black wire groud and the chassis ground.

 

[Jaycenk]

All you are doing is testing voltage. Voltage and amps are two different things. If you see a difference in voltage like that you can take it to the bank that you are not getting enough amps back to the pump to run it the way the system was designed. Amps are what the pump needs to operate under load so that small drop in voltage shows that you are loosing at least 1/8 to a 1/4 of the amps the pump needs to operate normaly. That loss of amps can cause pump failures and loss of pump speed under load. That means less fuel pressure and thus the lean condition as the lower pump speed will not keep the fuel pressure where it needs to be for the injecotrs to introduce the correct amount of fuel per cycle. Amps can only be tested with a load meter and they are not cheap. You did it right by re wireing it. More than likley the original pump when it was going bad would have needed more amps than the wires were originally designed to handle and may have caused the ground to have higher resistance due to high load from the original pump. Stock wires in the harnesses are made to get by. With the cost of copper in the modern era the harness wires and even you home wires are getting thinner to reduce weight and cost.