Fass Fuel Systems and air in fuel issues.

[Marcus2000monster]

Afternoon guys. As some may know I’ve had some issues with how well my truck has been running lately. It has been idling a bit choppy and an occasional miss nothing crazy but noticeable. we work on a few 24 valves at work and if never figured out why they run better than my truck does. I have been blaming it on low pop pressures with my fairly new DAP 75hp injectors but I’m thinking otherwise since a discussion with felllow employees at the shop. They mentioned that 8 out of 10 Fass fuel systems they have seen are actually making more air in the fuel system than they are separating. They are pumping far more fuel than the truck ever uses and returning it to the tank at a high volume that is creating air in the fuel in the tank. In other words it is making more air than it can separate. The more I think the more I suspect my running issues are air in fuel and not injectors. After all I only have 10K miles on my injectors. What do you guys think? @dieselautopower Have you ever had a set of injectors come back with low pop pressure at this low mileage? 

[Mopar1973Man]

1 hour ago, Marcus2000monster said:

Have you ever had a set of injectors come back with low pop pressure at this low mileage?

 

Mine did. I sent my first set of SAC injectors back with a miss and stalling issues. Less than 10k miles. Test out and sure enough couple where around 290 bar already.

 

Then there was @pepsi71ocean 28k miles and around 280 bar with 28k miles. 

 

1 hour ago, Marcus2000monster said:

They mentioned that 8 out of 10 Fass fuel systems they have seen are actually making more air in the fuel system than they are separating.

 

This is why I will not use the fuel module for suction and return both. This returns all the iar to the same confined space as the suction line. As for me I've got my return to the filler neck and the suction as a stand alone draw straw. 

[dripley]

29 minutes ago, Mopar1973Man said:

This is why I will not use the fuel module for suction and return both. This returns all the iar to the same confined space as the suction line. As for me I've got my return to the filler neck and the suction as a stand alone draw straw.

 

Mine has been running with the both returns and the pickup in the basket for 8 years with out any problems with air. IIRC the returns are a couple inches above the bottom of the basket or right near the top of the basket. Seems if that was the problem I would have experienced it by now. 

 

I cant really disagree with what you are saying, I had a lot second thoughts well after install but it has worked just fine.

[Mopar1973Man]

Might have to do with the differences between the FASS and AirDog flow rates. Being we both have AirDog and @Marcus2000monster is talking FASS fuel system.

[BBHD]

19 minutes ago, dripley said:

 

Mine has been running with the both returns and the pickup in the basket for 8 years with out any problems with air. IIRC the returns are a couple inches above the bottom of the basket or right near the top of the basket. Seems if that was the problem I would have experienced it by now. 

 

I cant really disagree with what you are saying, I had a lot second thoughts well after install but it has worked just fine.

This is how my FASS150 is set up. I have over 100k of absolutely trouble free miles with it so far since I installed it. 

[Marcus2000monster]

I want to try a clear hose test to determine if they’re actually is air coming thru. My fass has always made a odd noise that could possibly sound like air moving through? 

[trreed]

I used to have issue with that pump getting junk air separator filters that caused a rock tumbler sound. Try changing the filters and see what happens. 

I never had performance issues when it made those sounds though. 

Edited January 27, 2019 by trreed

[Dieselfuture]

It's all on how you set it up. If fuel returns to lowest spot possible, then there should be no air, if you dump it from top then it will foam. Size of lines also matters. Mine is in basket and been fine for a while now.

[NIsaacs]

I just did a fuel gauge sending unit in my '01. The return line is attached to the external side of the module, about 2-3" above the bottom of the tank.

 

My opinion only: The screen is too fine for diesel in cold climates, it appears to be a gasser screen. I really think the module is a hybrid/modified gasser unit. It had a one way valve that hooks up to nothing. Like it is for an in-tank pump. The bottom half of the module holds fuel, again, like it is for an in-tank pump for cooling, when the tank is low. I removed the valve and top screen off the sump/basket and made two holes in the bottom screen.

 

My tank was spotless and only a slight amount of dirt in the bottom of the module. The screens were covered in a varnish like coating that appeared to be a restriction. I am not a fan of the big aftermarket fuel pumps, too hard to get parts on the road. I also think they cause more problems than they fix. I have a Raptor direct mount now after several oems, an Aritex and DDRP direct mount pumps. I carry a good used Carter just in case.

 

My float was totally worn out.

 

 

[pepsi71ocean]

My fass95 has made noises since day one, however for me running 1/2" line from the tank to the fass then using 3/8s everywhere else did quiet the pump down. 

 

The design as far as I've seen hasn't changed my idle at all since most of the fuel that goes to the VP tends to go right through the bypass check valve in the VP.

 

Filter size does play a role here, as the amount of air created by the fass is based on the restriction placed on the pump on the suction side. 

 

I did the test you speak of and the air bubbles were really small it almost looked like solid fuel to me.

 

However for me I have seen a difference in idle with my Injectors when they were popped higher. Also changing my smarty settings as well.

 

 

[Marcus2000monster]

9 hours ago, trreed said:

I used to have issue with that pump getting junk air separator filters that caused a rock tumbler sound. Try changing the filters and see what happens. 

I never had performance issues when it made those sounds though. 

I nearly forgot I bought this pump from you! Lol. I’ve definitely got my moneys worth thank you much! I’ve honestly gotten used to the noise but I just started thinking about it again after my discussion at work about the Fass pumps making air. The pump has done well it has held 20 psi at idle sine I bought it off you. 

 

8 hours ago, Dieselfuture said:

It's all on how you set it up. If fuel returns to lowest spot possible, then there should be no air, if you dump it from top then it will foam. Size of lines also matters. Mine is in basket and been fine for a while now.

Mine returns to the filler neck. I can only imagine how much froth that creates with the volume of fuel that gets returned. I’m not dead set on my issues being from air but it’s got to be that or injectors. Can’t decide what to blame it on because it’s so intermittent. Some times the. Truck will run perfect smooth idle and all. 

[dripley]

3 hours ago, NIsaacs said:

I just did a fuel gauge sending unit in my '01. The return line is attached to the external side of the module, about 2-3" above the bottom of the tank.

 

My opinion only: The screen is too fine for diesel in cold climates, it appears to be a gasser screen. I really think the module is a hybrid/modified gasser unit. It had a one way valve that hooks up to nothing. Like it is for an in-tank pump. The bottom half of the module holds fuel, again, like it is for an in-tank pump for cooling, when the tank is low. I removed the valve and top screen off the sump/basket and made two holes in the bottom screen.

 

My tank was spotless and only a slight amount of dirt in the bottom of the module. The screens were covered in a varnish like coating that appeared to be a restriction. I am not a fan of the big aftermarket fuel pumps, too hard to get parts on the road. I also think they cause more problems than they fix. I have a Raptor direct mount now after several oems, an Aritex and DDRP direct mount pumps. I carry a good used Carter just in case.

 

My float was totally worn out.

 

 

Is this the basket you were dealing with? This is the intank basket that Dodge installed for me when my oe lift pump died. I was also under the impression that this is what was in the early 3rd gens also. My return and supply are facing the camera and the black on the outside of the basket went to a capped fitting on top and as I remember did nothing. Both my returns now go to the old return and supply straight into the basket and I drilled out a new hole for the pick up. I had a couple after pictures but cant seem to find them. 

[NIsaacs]

2 hours ago, dripley said:

 

Is this the basket you were dealing with? This is the intank basket that Dodge installed for me when my oe lift pump died. I was also under the impression that this is what was in the early 3rd gens also. My return and supply are facing the camera and the black on the outside of the basket went to a capped fitting on top and as I remember did nothing. Both my returns now go to the old return and supply straight into the basket and I drilled out a new hole for the pick up. I had a couple after pictures but cant seem to find them. 

 

Thank you for the pictures, I wasn't smart enough to take some Mine looks like this one in the link. I might be wrong on the outside line, it might go to the capped fitting you mentioned, my eyes don't see all that well, lol.

 

https://www.genosgarage.com/product/mopar-fuel-tank-module-sending-unit-4897668/fuel-system-accessories-replacement-parts

[dripley]

4 minutes ago, NIsaacs said:

 

Thank you for the pictures, I wasn't smart enough to take some Mine looks like this one in the link. I might be wrong on the outside line, it might go to the capped fitting you mentioned, my eyes don't see all that well, lol.

 

https://www.genosgarage.com/product/mopar-fuel-tank-module-sending-unit-4897668/fuel-system-accessories-replacement-parts

Just wanted to be sure we were talking about the same thing. It gets easy to compare apples to oranges sometimes. It is easy for me sometimes not knowing the difference between years and such. 

[JAG1]

Marcus2000monster ,It seems that if it were an air problem, the symptoms would go away with a full tank. Or at the least be less noticeable.

 

How about checking for the infamous AC ripple levels?

 

Have you completed the W-Ts grounding mods? Both my trucks seemed to run a bit more like a cats purr afterward.

 

Check the condition of the PDC ground, an important one down on the fender in front of the drivers battery. It is often hidden by the wire harness running over that grounding bolt. 

 

Condition of the batteries and connection posts.

 

Unhook the VP connector and inspect all the pins for any minute distortion.

 

Just go over things in general on the electrical side is my lean anyway.

 

 

 

 

 

 

 

 

 

 

 

 

Edited January 27, 2019 by JAG1

[Mopar1973Man]

Some days I wish @Marcus2000monster just would come over the mountain to Idaho and let me look at it. 

 

[Marcus2000monster]

36 minutes ago, JAG1 said:

Marcus2000monster ,It seems that if it were an air problem, the symptoms would go away with a full tank. Or at the least be less noticeable.

 

How about checking for the infamous AC ripple levels?

 

Have you completed the W-Ts grounding mods? Both my trucks seemed to run a bit more like a cats purr afterward.

 

Check the condition of the PDC ground, an important one down on the fender in front of the drivers battery. It is often hidden by the wire harness running over that grounding bolt. 

 

Condition of the batteries and connection posts.

 

Unhook the VP connector and inspect all the pins for any minute distortion.

 

Just go over things in general on the electrical side is my lean anyway.

 

 

 

 

 

 

 

 

 

 

 

 

That I will do. To be honest I do think that it runs a bit better with a full tank. 

 

I have not checked for for ac noise since I replaced my alt. Will do so soon. 

 

I have bit bit done the mod I would like to when I get some spare Time. 

 

I will I’ll check out that pdc ground. Battery’s and terminals are in most excellent shape. 

[Mopar1973Man]

5 minutes ago, Marcus2000monster said:

To be honest I do think that it runs a bit better with a full tank. 

 

I've seen the pickup tube crack on stock baskets and cause the truck to run out of fuel at a 1/2 tank. Now did you install a draw straw?

[JAG1]

1 hour ago, Mopar1973Man said:

Some days I wish @Marcus2000monster just would come over the mountain to Idaho and let me look at it. 

 

Be careful though.... if you hear rattles from your intake tube, when you leave, there's probly bolts put in there. 

[Mopar1973Man]

Just now, JAG1 said:

Be careful though.... if you hear rattles from your intake tube, when you leave, there's probly bolts put in there. 

 

@JAG1 Stay in Oregon, then the rattles stay there too.