My 92 f150 5.0 SD started stalling the other day. Figured the pump went out so decided to take the bed off to replace both pumps at the same time. Got the front pump in now hooked up but doesn't make any prime noises. Rear tank will come on no problem . I pulled the pump out to double check my wiring looks like I did it right so we try wiring the other new pump for the rear to see if we received a bad pump. Doesn't prime up either. Tried replacing the fuel tank selector switch still no power to front fuel pump. Any help would be great

 

Inertia switch has been checked also

 

On the 1989 f150, there is a fuel pump relay located on the left side of the engine compartment. It is in line with the readout plug for checking engine codes. About $17.00 at Auto Zone.

 

Bought new fuel pump relay but problem is still happening. I tried the #2 & #6 jumper wire on the EEC test connector, rear tank will come on but not the front.

 

Remove the fuel line from the front of the frame mounted pump. switch to the rear tank and see if it is pumping fuel. Also there is a time switch that will cut off all pumps if you don't try to start the engine within one second. This means that it trying to determine if the fuel pumps are working you must turn the key to start.

 

Yeah the rear tank is working, will prime when ignition is on and will run but nothing from the front tank. No prime or power when selecting tanks.

 

Will it run on the rear tank?

 

Yeah it runs on rear

 

Bad pump or a bad plug that plugs onto the top of the tank.
You can buy a pigtail with plug at some auto part stores.

 

Having just changed the center in my truck, I know that the plug is hard to seat because it is a bit short and you can't see it and for me I had to put it in by feel. You might have to pull that tank and make sure it is seated properly. From what I read here earlier you did not replace the whole sending unit but simply the fuel pump. You might have wired it wrong. You can pull the tank switch and test for voltage to the center tank. Remember you only get voltage to the tank for one second unless you actually move the key to the start position.

 

We got the bed off hoping to do both tanks but stuck working on the front tank. Last night I checked the pigtail connection n tried fixing a section. I am very positive that I wired the pump up right. I bought a circuit tester that connects to the negative battery and another tester that connects to both the positive n negative terminals to check both power and ground. Also last night tried exchanging the pump and still no prime or coming on after starting the truck up and running it on the rear tank then switching to the front. How and where should I begin testing?

 

 

Cleaned the connections

 

Since you have the bed off the truck, I think the place to start is to remove the pump from the tank. This way you can feed it voltage and see if it runs. You may just have received a bad pump. It does happen from time to time.


This is from the shop manual for the 1989 F150.

 

This is a section of the wires I cut out and re did it thinking it was a ground problem. Was this done from factory or from someone at a shop at one point in time?