99 Ranger fuel pump won’t kick on

[Briantheranger]

We’ve replaced the fuel pump twice and still aren’t getting it to kick on, we’ve tested the relay, inertia switch, and checked voltage at fuel pump connection and voltage seems to be good. Any other reason the fuel pump wouldn’t kick on even if it’s getting power??

 

[franklin2]

Make sure you check for power at the pump connector WITH THE PUMP STILL PLUGGED IN. This is a common problem when troubleshooting electrical, if you unplug the load, you will get 12v. Once you plug the load in, if there is a wiring problem upstream, the voltage will drop.

 

[RobbieD]

And, the pump also needs a good ground in order to run.

 

[Briantheranger]

Make sure you check for power at the pump connector WITH THE PUMP STILL PLUGGED IN. This is a common problem when troubleshooting electrical, if you unplug the load, you will get 12v. Once you plug the load in, if there is a wiring problem upstream, the voltage will drop.

where should I be holding the leads to do this?

 

[Briantheranger]

And, the pump also needs a good ground in order to run.

where is the ground located? We’ve looked and can’t find it

 

[RobbieD]

I'm sorry; I don't know on a '99. Maybe someone that knows the newer trucks will chime in.

 

[franklin2]

where should I be holding the leads to do this?

It's a pain, but if you can, stuff your DVOM leads into the back of the plug where the wires go in. They make slender probes with short wires attached for this purpose, if your leads won't fit maybe you can make something from a straightened paper clip or something like that.

The ground could be anywhere in the truck, they quit making grounds to the frame in the back and usually have them up front somewhere in the cab. I don't know where it is either on this truck. On the 1980-1986 trucks the main ground was behind the radio on the firewall.

 

[sgtsandman]

where should I be holding the leads to do this?

The best way is the back probe to connector. There are two ways you can tackle this. 1) Go to Harbor Freight and buy their back probing kit 2) Get some T-Pins. Walmart might have them in the section that has sewing stuff or find a craft store like Michael's. It's easier if you have multimeter wires with alligator clips to use these but you can make a regular wire work.

 

[sgtsandman]

where is the ground located? We’ve looked and can’t find it

Find some bare metal on the frame. That will provide you with a ground.

 

[pjtoledo]

hopefully a 1999 is similar to a 2000,,,
on a 2000 the fuel pump ground is G200 which is a screw near your left foot and the license lights use that same ground.

 

[franklin2]

Find some bare metal on the frame. That will provide you with a ground.

You can run into trouble doing that. If the ground the pump uses is no good, then you will end up with a head scratcher, power at the plug but the pump still won't run. I always try to use the same wires that the pump or device uses.

I see the next poster in the line-up says the ground is up front at the kickpanel. That makes sense, I have heard of some of the later full size trucks having a important ground down low at the kickpanels, and they have problems with corrosion there sometimes on those.