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I have a 1996 f150 bifuel 6 cyl, 4.9. Fuel pump rear tank does not work. New fuel pump. I show 12 volts on the wiring harness where the fuel pump on the rear tank plugs in, when i plug fuel pump to wiring harness, i show 0 volts
suggestions?
Hello;
You may have a break in the wire inside the tank to the fuel pump. I have seen the wires disconnect as the pump is installed.
Rich
RPM Northwest
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Hello. Your Chevy's fuel pump assembly color code wiring should be grey (power) black (ground) purple (fuel level) and orange (low fuel warning). To check, attain a 12 volt test light and probe the wires one by one as an assistant turns the switch on and off without engaging the starter. Good luck and keep me informed; if you want to.
see if your wires are getting 12 volts , do you have a tank switch on it , alot of trucks have a switch to change tanks from one to the other ,ck your manual
The plug you are referring to is probably the fuel tank pressure sender not the fuel pump. It would be plugged into a black sensor about 2 inches long pushed into a rubbergrommet on the fuel bung. The fuel pump connector would have more that 2 wires going to it. most likely a heavy purple wire would be the power to the pump. It has to have 12 volts to it to work. The sender may have 3 wires, 5 volts, ground, and sense. the pump connector would have 12 volts, ground and 5 volts for the fuel gauge sender down in the tank.
If the 12 volts is not there, check the fuel pump relay. it is usually up on the drivers side firewall.
With the key in the on position without starting the engine, you should have 12 volts to the pump for 3 seconds then it will click off. Without cranking the engine you should be able to locate the relay by the clicking sound.
There is also the obvious, like checking the fuel pump fuse.
I have a 1996 f150 and I had the same problem. I finally found out that the rear fuel pump is the main pump, and if it goes out then the front pump will not work either. There is a groud that both pump share on the rear cross member. If you are not getting good connection with the ground the fuel pumps will not work. Also if you replace the rear pump and it still does not work then your problem could be the fuel tank selector switch, it acts as a relay if it goes out then neither pump will work.
Do you have a fuel guage reading for the rear tank when selected? Unplug the rear tank fuel pump electrical connector and check for voltage on the terminal with the brown/ white wire and the orange wire should be twelve volts. If nothing then measure the orange wire for continuity to ground should close to 0 or .1 ohms. If no continuity between ground and the orange wire then you have an open on the orange wire this needs to be repaired so that when you test for continuity again it is within range. If you have twelve volts now between the connector terminals. Plug the connector back in and try the pump again. If you had 12 volts to begin with disregard the repair above. Unplug the front fuel pump electrical connector and test for continuity between the terminals on the tank that the red and orange wires go to. Record the readings. Now you a baseline of what the rear tank fuel pump should read. Now do the same test on the rear tank between the terminals on the fuel pump where the brown/white and orange wires go. Chances are you'll find out the rear pump it self is bad from not being used for a while.
there were some production changes in 1998 to the fuel pump wiring, so the connector can have 2 diff fuel pump power wire colors, the most common color is grey, but the the harness at the tank has just 4 wires, the larger wires at the four wire oval connector are the fuel pump 12 Volt and the other is the ground, it is black, the other 2 wires are the sending unit, also the connectors ( Chevy factory service bulletin) on this year had a problem with burning, so if you get a new fuel pump always replace the 4 wire fuel pump connector. I have attreached a picture of the connector
The wire should not be hot until the relay is triggered. The relay does not get triggered until the ignition key is turned on. It will run for 3-5 seconds or until the system pressure it at max.
your truck is a 4.9L, make sure you have power to the front tank fuel pump. is the power to the pump is ok and you can hear the pump run for a second or two when you key the vehicle on... replace the fuel tank selector valve
my idea, the pumps are working agianst each other. what is the line pressure supposed to be? I think the rear pump is burning the new pumps up. is the rear pump running when the front pump is running? Let me know [email protected]
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