OK....dont put the pump on its side....its not designed to do this and the only reason you are getting it to move fuel is you are splashing it with fuel from the water separator.

OK...so the truck is a 98.5......was it ever taken to the dealer to get lift pump work done? They will convert to the in tank pump if this happened in the last 2 or so years. If you have an in-tank pump, our system will not be happy and some times they WILL NOT prime at all. Too much restriction.

I think you have proven your issue is in the tank as you were able to pull fuel from a bucket and not the tank itself. I would try this test again. Just pull the tank line and the FASS return line and place in a bucket of fuel. Run the pump with the FUEL filter cracked loose only until the pump starts to prime. Then tighten up the filter. Run the pump. Note if you have return fuel or not through the FASS return line. If you have return fuel you more than likely are making pressure. Still like to see a gauge reading.

Let it run for a while. Shut it down and see if it will reprime or not. If it does….let it run again for a while.

THEN hook everything back up and see if it will pull fuel from the tank or not. If it doesn’t, you will need to drop the tank and address the issue.

I’m still leaning towards an in-tank pump conversion. (forgive my repetitiveness but I see this on a daily basis) Do you know the history of this truck or is new to yall?

 

I installed the FASS about 1.5-2 yrs ago. I have had the fuel sending unit and pick up tube assemble removed from the truck. There is no in tank lift pump.

When I had the pump out of the truck with the pickup tube in the bucket and the water seperator full of fuel and the filter cracked. It would not prime until I tipped the pump on its side. As soon as I did that it started pumping right away. It worked fine after that. When I put it in the truck it ran for about 1 minute and primed. We had it on and working for about 10 minutes trying to get the truck to start. Pump was shut of for about 10 sec. and lost prime and wouldn't prime again. Then I took it out tipped it on its side and it prime instantly 17psi placed back upright and no pressure.

 

Ok

Removed suction line and put it in a bucket cracked filter loose. Pump will not prime. Has no suction.

 

When i put mine on i had to put fuel in the filters before it would prime

 

It has fuel in both of them.