12.3, new battery just cranked on.

 

I assume you mean 12.3v with the ignition on.if so then you either have a bad pump or a wiring problem from the pump relay to the pump or the pump ground. Either way the tank has to be dropped to either fix the wiring and or to replace the pump. Once the tank is dropped we need to backprobe power and ground with the pump still connected and see what the net voltage is at the pump during the key on priming cycle.


George

 

On a side note the guy gauge sometimes reads full next second empty and vice versa. Are these 2 problems connected?

 

That just confirms that you have either a failing pump and or a wiring problem. I keep adding wiring because many an expensive replacement pump has been installed only to still have the problem and then find out that the solution is a $0.10 piece of wire. This is a strong possibility for you because of the physical trauma of the engine swap and its always a possibility in a 20 year old truck.

The gas gauge sending unit and fuel pump are part of the same assembly. We can check the sender wiring while you have the tank dropped.


George

 

Just now getting back to this, been raining and I am working on it outside.

My help is a little rough and broke a plastic nipple on the fuel pump so it has to be replaced.

How do I go about checking the wiring?


Looks like he got this piece too, what is it called?