FASS quit, truck still runs?

[Axion]

My FASS 150 has started blowing fuses. Contacted FASS and the warranty ran out last year (of course). I will order a replacement, but they are back-ordered (again, of course). I have switched back to the factory in-tank pump so I should be okay until I can get the replacement in.

It was probably a day before I noticed that the sound of the pump running was absent, but the truck ran fine. I would have thought that I would have noticed a drop in performance? The CP3 must have been pulling what it needed through the FASS. Can I expect my CP3 to start showing problems any time soon?

Thanks in advance for any and all advice.

 

[cerberusiam]

Depends on how hard you were driving it. The CP-3 will pull fuel thru a failed vane type pump as long it doesn't loose prime, do NOT change the filter until the pump is fixed or you will never get it primed again.

A day or 2 or even a week or 2 normal driving without the LP is likely not going to hurt anything as long as you don't have symptoms of low fuel delivery.

 

[Axion]

Thanks cerberusiam. That definitely makes me feel better. My driving has been a pretty calm 12 mile commute from the RV to the rig for the last week. Glad it didn't quit while I was towing.

Once I created this post, the wonderful forum software listed some similar posts at the bottom of the page. After reading those posts it would appear that the pump has a bypass channel to allow fuel flow in case of a pump failure. And the CP3 is able to draw through that bypass on its own.

So now I order a replacement, once it gets here I can do a quick swap and then send the old one back for rebuild. Then I can carry the rebuilt one around for 7 years until the new one fails!

I figure I'll install the FASS heater kit and a fuel pressure gauge while I have everything torn apart.

 

[RCHAWES]

I had a FASS 150 on my 2003 and I always had blown fuses as well and truck ran fine and no drop in performance. Only had it on mild tune 60hp. Found that the fuse was mounted under the hood below my windshield wipers and rain water/washing was causing the fuse to get wet and then blow. Changed locations didn't have any issues after that.

 

[Tuesdak]

Fuses popping could be from a couple things.
High current draw from a bad or jammed/jamming motor. (Bering locking up, debris, pump elements scoring up, windings shorting out in the motor.)
Intermittent shorts popping fuses at random. Wiring up to and including inside the motor including brushes and brush insulators. A wiggle test on wiring for the pump is in order if it will run at all.

What is the current draw of your FASS pump when running? Does it still run till it pops a fuse?

Can you unplug the pump somewhere near the pump and use a test light to check for a dead short? Test light goes across the removed fuse to help find the short - the light goes out when you remove the short. Useful for wiggle testing wiring.

Have you tried the "Slightly loosen 3 of the 4 bolts of the base of the motor while holding the motor to the base" trick to allow debris to pass through?

Can you get just a new pump section or motor parts rather then entire thing?

 

[JCockerill]

how many years and miles did you get out of that sump pump? just want to low when i should expect mine to die. at least its loud enough to know when it not working!

 

[WoodChuck]

The FASS has check balls inside that allow fuel to free flow if the pump doesn't run for some reason and Chevy's DuraMax (same Bosch common rail fuel system) were originally designed without a lift pump (something they changed after a few years). My FASS motor died recently after 210k miles and I was able to rebuild it locally for $150 (but then I had to chase down a seal from NAPA) and I had a relay go out on me once. I try to be conservative when the pump isn't working but sometimes I forget and get into it a little harder than I probably should and it seems to run fine.

 

[Axion]

No obvious shorts while testing at the plug on the pump. A wiggle test would be a ton of work as the wiring was very well secured along the length of the truck. I will try to do more testing once I have the old pump out of the truck. I have very little experience rebuilding electric motors. I wouldn't mind experimenting on the old one but since I use the truck for work, I think I'll use a new replacement from FASS just to be sure.

I installed the FASS in August of 2007 with 64535 kms (40100 miles). Went back to the factory pump in May of 2014 with 348908 kms (216801 miles). So, 6 years 9 months and 284373 kms (176701 miles). I guess thats not too bad. Hopefully the new pump will last just as long.