Engine/Transmission (1998.5 - 2002) FASS not pumping after filter change

[Troubleshooter]

Not sure why it didn't work; and I dang sure don't know what got it working again.



Had something odd happen tonight after a filter change. I’ve got the FASS DDRP-02 on the truck, and tonight after changing the fuel filter and the pre-filter, I went to bump-start the pump and expel the air in the lines, and got ……. Nothing. Normally, the pump runs for about 25 or 30 seconds, putting good diesel in the lines. But not tonight! I’ve done this job a dozen times or more and have almost always been able to expel air in the lines by bump-starting. Only had to open the banjo bolt once to bleed the system. Never had anything like this happen.



So I tried again, still nothing. Checked the fuses, tickled the wiring, cussed at the FASS; zip, nada, zilch. I had just installed a new Vulcan line to the pressure sensor, and knew that there would be air in that line, so I popped the fitting and tried again. Still nothing. Checked for codes and all I got was the P1693. No big deal, that’s probably the Smarty. Re-checked the lines, cussed a spell, tried the key again; no joy. #@$%! Went under the truck and checked the pump and pre-filter, everything’s as it should be. Cussed some more. #@$%! Hmmm…. As long as I’m down here, I might as well check the block and see if this one has the “dreaded 53 block. ” Nope, got something that looks like “2C” or maybe it’s supposed to be “20” but no 53. Kinda hard to see beneath all the wiring and hoses.



Went outside and got some air. Contemplated going online and posting a “911” on it. Came back in and re-checked everything, and tried bump-starting one more time. This time, success! Bumped it a couple more times while checking for leaks; bled the new Vulcan line; torque everything down good and tight, and started ‘er up. Started first time. Got out, checked again for leaks, checked pressure and it’s right where it should be. Went out for a test drive and all is normal.



Except that I can’t for the life of me figure out why the FASS would not work initially. I have no idea what if anything, I might have done that “fixed” the situation, as nothing appeared to be wrong. Anybody else have this happen to them?



Thanks in advance for any insights.

 

[barryg41]

When I got my FASS, I installed it in the OEM location. No problems getting it to prime the lines. Then on the next filter change I decided to move it next to the fuel tank. Still no problems with the FASS. It has never missed a lick.



I do remember the fist time I ran the FASS pump that I had a hard time hearing it. The old pump was so noisy. I kept bumping the truck over to get the pump to run 20 secs or so. I didn't even realize that I had diesel going to the ground.



Everything runs good and I am getting 22lbs at idle.

 

[ArmandoCantu]

I have a FASS 95, bought 5 years ago. Runs great. But on filter changes I have to do the filter trick the instructions say to do if the system doesn't prime. Loosen the filter cartridge until you hear the pump change pitch. Works every time... . Only complaint is that i only see 13 - 14 pounds at idle and down to 11-12 pounds on acceleration. I'd like to see @ 15 pounds all the time. Any ideas?



P. S. My bad, I bought/installed the FASS 2 1/2 years ago.

 

[KKlingbeil]

My experience with this is to just fill the fuel/water separator with diesel, but not the actual filter. This way the pump primes right away, but still pumps the fuel through the filter. It will prime right away doing this. I had the same experience as Troubleshooter, as the FASS wouldn't prime, the first time I changed the filters. Adding fuel to the water separator has worked every time since.

 

[Troubleshooter]

But on filter changes I have to do the filter trick the instructions say to do if the system doesn't prime.

Instructions? These things come with instructions??? :-laf



But seriously, mine was installed by the shop where I bought it, so I've never seen the instructions. Thanks for the tip; I'll try that if it happens again.

I do remember the fist time I ran the FASS pump that I had a hard time hearing it. The old pump was so noisy.

Mine is loud enough that I can hear it when it runs. I should mention that in normal operation, my FASS sometimes will not prime the system when the key is turned to the "wait to start" position. Once the truck is actually running, it pumps just fine.

 

[BBeckmann]

If ur not getting the pressure ur supost to r had it change on u there may b blockage in the lines r the spring may b getting week, call up fass and they'll send u a new one no charge. I just had them send me one and it's fixed pushing around 44 to 45 again. Mine is a 12v tho...

 

[rkressg]

As far as pressure, if you want a quick fix to bump it up, pull the regulator off, and stretch the spring a little. This will increase the fuel pressure.

 

[Sticks]

As far as pressure, if you want a quick fix to bump it up, pull the regulator off, and stretch the spring a little. This will increase the fuel pressure.

Or shim it. IIRC they do sell a shim kit.



I have the same thing with mine (14 idle, 11-12 WOT). Still above 10 so I don't stress too much on it. One day I will address it.

 

[Troubleshooter]

Thanks for the tips, gents. Reckon that I need to check into that spring. Where is it located?

 

[BBeckmann]

The spring is on the front of the aluminum pump body where the fuel line comes out, above the water seperator... Where the fitting is screwed into the housing and the line is on that. Take line off and put it up high so fuel won't run onto u then unsrcrew the fitting, a lil black ball will roll out with some fuel so b ready to catch it or it'll disapear into the rocks! Ask me how i know, Haha then pull out the spring and strech it a lil unless u have a new kit... Reverse everything and ahould b good to go. . I replaced mine and it went from 25-30psi back to around 42psi at idle... So now i have a spare spring and check ball around... (I found it back) And good as new again.

 

[Troubleshooter]

There is no fuel separator on mine, but I'll take a look and see what I can find.

 

[Sticks]

OK, You have the DDRP - which if I am thinking correctly is just the pump, no filters attached, which means the filters you changed are the OEM one on the block and ... what pre filter?

Back to your original issue, I have often run into trucks (including mine) that for some reason don't cycle the pump when you bump the starter. Don't know why, but it happens, I just have to repeat several times. This is also why I have a pigtail made (tool) that plugs into the harness down by the OEM mount with clips to connect direct to the battery. I generally use it when I do VP replacements.

As far as where the pressure relief valve is on your FASS model, by looking at the pictures on the FASS website, there should be a line in, line out, and what ever extra fitting there is (cap) on the housing will be the valve if so equipped.