Engine/Transmission (1998.5 - 2002) Noisy FASS

[pharlacher]

Sorry

Now all three seem to have showed up. Weird. I just looked a couple of minutes ago and they were not there.

 

[DWeiler]

noisier pump too

Well after 6 months of having the Fass i finally got to load it down with some towing weight ,went about 500 miles. After i got back i was unloading the travel trailer and notice i could hear the pump now. Pressure is about 17 at start up and after everything is warmed up it seems to drop to 14-15psi. I just changed the filters a month ago so i think i can rule that out. When i first got the Fass i reached under the truck and felt the motor running its seemed real smooth,quiet, now it feels like more vibration and noise and not as smooth. IT still works but i guess i am going to have to watch it now,maybe see if it get any louder,hopefully not another fuel pump failer . Maybe Brad from DPP will chime in and offer some ideas. I really don't want to take the unit out unless i have to.

 

[todt061458]

OPoole you have mail Oo.

 

[GKinney]

loud fass

I just completed a siphon tube upgrade on my 98. 5, went from the stock crap to a 1/2" drop pipe in the tank and -10an hose to the fass. Talk about a BIG difference. Before you could hear the pump surge, like it was starving for fuel. Now it just purrs with a dull even humm. I removed the fuel cap and listened in the filler hose and could hear the bypassed fuel dumping back in the tank. It is circulating some fuel now like it is designed to. But going from a less than 1/4" I. D. (. 210") quick disconnect fitting to a full 1/2" would reduce the work load on the pump. Hope this helps... . it did me!!

 

[Mad Bomber]

PU tube?

I just completed a siphon tube upgrade on my 98. 5, went from the stock crap to a 1/2" drop pipe in the tank and -10an hose to the fass. Talk about a BIG difference. Before you could hear the pump surge, like it was starving for fuel. Now it just purrs with a dull even humm. I removed the fuel cap and listened in the filler hose and could hear the bypassed fuel dumping back in the tank. It is circulating some fuel now like it is designed to. But going from a less than 1/4" I. D. (. 210") quick disconnect fitting to a full 1/2" would reduce the work load on the pump. Hope this helps... . it did me!!

Do you have any pics of the drop tube? What did you use? Parts list?TIA Eric

 

[GKinney]

parts

Mad Bomber,,, sorry I don't have any pics. of the pickup tube. I just used a piece of 1/2" black iron pipe connected to a bulkhead fitting that went through the hole I drilled in the top of the tank. I do have some pix of the bulkhead fitting and hose I used if you would like to see them. PM me and I can e-mail them to you. Sorry so late posting, just now found that you had replied. Hope this helps.

 

[Aaron_A]

I still need to modify my fuel pickup tube as well. My truck starts hard and FP jumps around when the tank is less than 3/4 full. Soo I supose my pickup tube is rusted or bent or whatever,Im going to smash it with a BFH when I get it out of there #@$%!

 

[GKinney]

fuel level

Aaron, sounds like you have the same case that I did. Mine when down to about 1/2 tank wouldn't pick up pressure when switching the key on. After starting the engine it would pick up the fuel and the pressure would jump up all at once. The only thing I really found wrong with the fuel module was the tin where the bucket slides had some notches wore in it not letting it drop down. I filed the burrs off and it worked better. Still a seperate suction tube is the ticket!!

 

[Briman]

Are these all 150 GPH units that you guys are having trouble with? I just bought a 95 GPH for my truck (not installed yet) and then stumbled onto this thread. Makes a guy nervous.



The manual that came with mine said the 150 gph pump could/would make noise with the stock pickup and the pick up may require mods or replacement. The manual also said that the 95 gph pump should work well with the stock pick up. So what size ya'll runing?



Sounds like gravity feed out the bottom may be the way to go. I guess water would not spend much time in your tank that way.

 

[tractorface]

Not sure what size mine is

Bottom feed would work but most like me feel the danger of some type of leak draining your tank outweighs the benefit. It can be done though. The real problem is the overly restrictive OEM tank module. DC installed some type of cheesey valve that really restricts the flow of fuel. Most fuel systems I work with on Diesel gensets, are very particular about the amount of restriction allowed in the fuel supply line. Remove as much restriction as possible in your system and I believe the fuel related problems will go away. Your FASS is a good unit, I would not worry about it, I would at the very least remove the valve/screen assembly from your OEM fuel module. There is no reason to run that mess when you have a nicely filtered system. The FASS takes care of the water and any crud and the best part is you can change/clean those filters without removing the fuel tank.

Bottom line is DC mass produces trucks and saving a few dollars here and there is how they make big $$$. This time they scrimped in an area that they should not have. I am certain some of the OEM fuel modules are better than others, that is why you see some guys on the OEM lift pump for so long. It is not the pumps, it is the TANK MODULE.

Off my soapbox now

 

[GKinney]

tractorface,,,, I really didn't see much wrong with my module,,,although I didn't completely dismantle it either. I do know that yes it is one BIG restriction even with the stock lp I'm sure. Then you try sucking 144gph through it, doesn't work well. I measured the quick disconnect fittings' smallest I. D. that came with the FASS and it was nothing like the 1/2" that I have now!! I also thought about the AN tank fitting on the bottom or side near the bottom of the tank, but my fears were like yours..... LEAKS??? I am glad that I went with the top line instead... . I am very pleased and urge anyone to do so with a high volume pump like the FASS. My $. 02.

 

[tractorface]

Hmm

Have heard of vast differences in the OEM module. Another member told me his fuel "pulsed" due to the module. I checked my old module and sure enough it pulsed wildly, looked like it would suck the valve at the bottom closed and then release over and over again. I had the module in an Aquarium full of diesel when I did this so it was real visible, and this was with my weak OEM lift pump. Should have made a video. After seeing this I was sold on the fact that the module is the source of the fuel problems in our trucks!

 

[TMills]

Is there any aftermarket replacements that would be better? Can someone post a picture of this module?

 

[GKinney]

:Tractorface,,,,, did you have fish in that tank when you were testing it???? . I wish I would have tore my module down and studied it to see what was going on but I was anxious to try my new suction pipe out... . you know how we kids are with a new toy!!! Oh do you have hot water running to your fass??? I don't yet..... trying to make up my mind.

:Tmills,,,,,, if you do a search on here under 'fuel modules' someone has some good pix posted of the module. Then there is another member that modified his with an fittings too... ... great pix. Hope this will help you out... I know I will never mess with my module again!!!

 

[tractorface]

Yeap The rare Diesel fish!

Actually many years ago someone at work built a clear tank for calibrating simple float type fuel gauges and it just sits and collects dust now. Looks like a fish tank on top of a steel tank. I used that and a monster CAT battery for power. I think the member selling the fittings to retrofit the stock module has the easiest/best solution. Can not remember his name but the search feature should turn him up. Look at what he did, should be cost effective and work well. My part requires welding etc. The sender I used can be used in any tank as it is available with the automobile standard mounting plate. Just install it close to the OEM module so you can thru bolt it. Mine works great.

 

[GKinney]

module pic

Tmills,,, here is a link to one of the members stock module pic. It shows most of it in the pic except the tubes on top. Hope this helps. https://www.turbodieselregister.com/user_gallery/displayimage.php?&photoid=14870&width=0

 

[TMills]

It looks like to me that the module would be the most restrictive part of the fuel system. I'm not sure about the size of those lines, but they look smaller than the lines used in the rest of the system. So why is everyone putting on fancier pumps and bigger banjo bolts when this is the most restrictive? Maybe the lift pumps are suited to do the job you just have to let them "breath" better.

 

[tractorface]

I agree

I have worked with Cummins fuel system engineers on several large diesel genset packages and they are always very concerned about the amount of restriction in the fuel supply line. We often install meters, valves, etc in the supply line and have to be very careful to keep the restriction very low. They usually publish a spec. say 2 or 3 in. hg. restriction max and still want it below that. I don't understand how oor why our trucks were set up like they are. I would love to get the Fuel module designer and the Cummins, Carter, and Bosch engineers in the same room and see where the fingers point.