On my brothers truck its my old truck so its the one in my sig. We are having problems getting the Fass to prime. Pump will come on and run but it is not moving any fuel. He did drain his water seperator so I loosened it and pressurised the tank and got it filled with fuel. That also tells me that everthing is ok in the tank. Took the supply line off the injection pump and can get fuel out of it when the tank is pressurised but nothing with the fass on and running. I have never opened up the pump so I am not sure how it works. Can it be rebuilt?

My bro is waiting to be approved so he will be a member soon.

Thanks

 

I guess we need a little more info. Is this a new fass? Is it the true fass or just the lift pump? Are all the lines clear? Have you tested the lift pump for volumn and to make sure it will actually pump?

 

If he has a H2O Separator... it's a FASS, not an HPFP.

To prime the FASS...need to loosen the FILTER side and bump the starter, until you hear the pump catch. I wait till it starts leaking diesel, to get all air out, before I retighten... but be down there and ready (with your hand on the filter). It happens fast when it takes off and the FASS flows a lot of fuel. Recommend a short sleeve shirt.

Trying to prime with the Water Separator won't work!

Good Luck

 

Ok loosened filter turned pump on no fuel. Took filter off no fuel when pump is running. We blew air in the tank and got fuel but the pump would start pumping. My brother is checking the lines for holes where it might be sucking air.

Can the pump be rebuilt?

 

i have had issues with 150's and stock pickups. do you have a pickup tube or is it stock?

 

Yes, all FASS & HPFP Pumps can be rebuilt, once you know they need it.

 

Got it fixed. He didn't tell me that he had messed with the wiring. Got it wired right and works great. We think that it was pumping backwards.

Thanks for the help!

 

Something is still wrong. It worked when he took it out of the truck and had it on the bench. Didn't run fuel trough it, it just sprayed what was in it all over the shop. But now with it back in the truck it wont prime. Loosened the water seperator made sure it was full of fuel. Loosened fuel filter wont prime pressured tank and got fuel to come out around the filter but it still wont prime.

Where can I get some info on a rebuild kit?

 

Take a 5 gallon bucket, put a couple of gallons of fuel in it, put your supply and return lines in there and see if the pump will pump it that way. That will tell you if it actually is the pump. As redline said it may be your pickup tube or something along those lines. It's fairly easy to isolate the pump to make positive thats the issue before you start talking about rebuilding it.

By the way, From how I read the orig post I'm assuming this pump has been running on the truck prior to the problems starting and it's not a new install right? I only ask because my first guess when I started reading the post was that the lines are hooked up wrong on the pump. The directions for the FASS are actually wrong and have you running your supply line back to the tank. That won't apply if I'm assuming correctly in that it's been working fine on the truck.

First thing though, 5 gallon bucket, isolate the pump to verify thats the real problem.

 

I dont think that it is something in the tank because you can blow with your mouth through a garden hose and get fuel to come out the pump.

 

That is not a good assumption......because what you can move with your mouth...the FASS moves 100+ times more....so what you think it not a restriction, could be to the FASS. You have to understand...if you have a 95 GPH or 150 GPH....its moving full pump volume all the time through that sending unit.....truck running, moving, idle or WOT. ALSO…what if your sending unit had a crack in the tube? You would have a very hard time sucking fuel and it would not seem like a restriction. I would still do the bucket test as suggested.

What you need to do is make sure the gear has oil in it. You can do this by removing the water separator and spraying WD-40 or something similar down the orifice that the water separator attaches to. It might be easier to do with the pump upside down. Run the pump if you can and listen for a gurgle. Then flip back upright and check for suction at this port (Make sure the fuel filter is disconnected if the lines are still hooked up). If you have suction, you should be good to pull fuel from the tank. If you still can’t get the unit to prime, im betting on something in the tank that is causing your issue.

How new is the install? I know the pump isn’t new….but is this a fresh install on this truck? Do we know if this truck has the in-tank pump or not? The symptoms that you are having sound like you do. Also, how much fuel is in the tank? I dealt with a guy yesterday that said he had a half a tank….but when he removed the fuel to drop it for inspection…..he only had 1.5 gallons…….finding his issue.

 

We are on are way out of town. I was planing on doing the bucket test when we get home. Pump has been in the truck for about 1.5 yrs. It doesn't have a pump in the tank. It has 3/4 of a tank. I am think about pulling the bed and check the inside of the tank.

If I had a problem in the tank with a cracked pick up tube I would be getting air out of the fass not fuel. Right?

I will be back Monday to get this thing running again.

Thanks for the help!!

 

Took the pump out oiled it and did the bucket test. Took some time to get it to prime but once it primed it worked fine. Put it back in the truck and nothing. Pump came on and ran but no fuel. Left everything hooked up unbolted the bracket layed the fass on its side and it started to pump stood it upright and nothing. Did this 4 times and got the same results.

What is going on?

 

Its starting to sound like a major restriciton in the tank.....

Does this truck have an in-tank lift pump?????? Its sure starting to sound like it.....

 

I had to tip the pump on its side to get it to prime in the bucket.

The truck is a 98.5 it doesn't have a lift pump in the tank.

When we first put the pump in the truck it took a few minutes to prime held 17 psi. Shut it off turned it back on and nothing. Unbolted the pump layed it on its side and pressure went right up to 17psi. Put it up straight and pressure dropped to 0psi back on its side and the pressure came back at 17psi.