jacwjames Posted June 9, 2022 Share Posted June 9, 2022 14 minutes ago, Rocketman3 said: I am also going to install a FASS pump soon, I also want to add a fuel pressure gauge. Please help me understand if I am interpreting my rig correctly… The first picture is where I am planning on installing the FASS pump. It is welded on so I will need to cut the bracket and use the bolt holes to bolt the FASS bracket on The second picture is the other fuel filter, to attach the gauge/sender unit, I just need to unscrew the brass piece (correct?). The red plastic cap was covering the brass piece. What is that for? It doesn’t look like a plug to me. The third picture is of the passenger side of the fuel tank. I see an unused extra connection (probably for the aqua hot that I don’t have). Can I just unscrew it to put the FASS return fuel there? Thanks! Just thought of another question… on the fuel filters - how do I know which side is input and output? On the first picture, I removed this filter and just used a union to connect the fuel lines together. Second picture, Yup, this is where I put my fuel sensor. Third picture, Yup, you should be able use that port for the return fuel line from the FASS pump. There is a IN/OUT for the fuel filter base, not sure how to tell, maybe someone else can chime in. Link to comment Share on other sites More sharing options...
tmw188 Posted June 9, 2022 Share Posted June 9, 2022 (edited) In my research it seems the line on the right in your first pic should be coming from the tank. You might be able to physically trace it and see if it heads up front or over to the lift pump? Check the video Mike from zmotorsports has out on YouTube. His install is different than what you are planning but should cover some of your questions with good video. The red rubber cap is just there to keep that fitting from getting dirty. Looks like it did it’s job. That spare fitting on the tank should work as Jacwjames said but I would see if it’s large enough to meet FASS requirements. If it was for AH it may be too small? Edited June 9, 2022 by tmw188 Link to comment Share on other sites More sharing options...
Notn2bars Posted June 10, 2022 Author Share Posted June 10, 2022 That fitting on your fuel tank has a very small opening. I removed the one on my tank and replaced it with a fitting that had a larger opening to make certain it would meet the requirements of the FASS return. Good luck with your FASS install and God Bless, Ed & Sylvia Here is a pic of the FASS return line with the replacement fittings. Link to comment Share on other sites More sharing options...
vanwill52 Posted June 10, 2022 Share Posted June 10, 2022 I'm not attempting to be sarcastic, so please accept what I say in that way. The FASS pump bypasses WAY more fuel than your engine can EVER use, even at WOT. So, it needs an unrestricted return flow line to operate in the way it was designed (not overloading the pump, even though it is internally bypassed). You simply eliminate the OEM lift pump from the supply circuit, and supply a dedicated return line from the FASS unit to your main fuel tank. FASS advises against "sharing" the return line with the one originally installed on the OEM lift pump. When you install a FASS system, it simply supplies MODERATE (+15 PSI POSITIVE) pressure to the inlet of the CAPS pump, instead of the factory-approved NEGATIVE 5 PSI it says the CAPS pump can "tolerate", as the result of the CAPS pump's internal "supply pump" The CAPS pump ALWAYS had to return excess fuel to the tank. By OEM design, it did this through a manifold on the lift pump. You can remove the lift pump from the process COMPLETELY when installing a FASS system. There are several ways to do this, and no particular one is more "right" than another. The simple requirement is that you must A) supply positive pressure at the INLET to the CAPS pump (NOT the INLET to the final filter) and B) supply a low-resistance return line for the FASS pump to discharge its excess fuel. Meet that requirement, however you do it, and you have satisfied the requirements of both the CAPS pump and the FASS system. Bottom line--However you do it, you are attempting to supply POSITIVE pressure at the INLET of the CAPS pump (NOT the INLET to the final filter), and an adequate return line for the EXCESS fuel not used by the CAPS pump. Link to comment Share on other sites More sharing options...
timaz996 Posted June 10, 2022 Share Posted June 10, 2022 I do supply my positive pressure to the inlet side of the final filter from the FASS pump which in turn is supplying that same positive pressure to the caps pump. The fuel is already being filtered better than the final filter so it should never get clogged. I just did this for ease of plumbing and be able to monitor the pressure at that housing. 1 Link to comment Share on other sites More sharing options...
vanwill52 Posted June 11, 2022 Share Posted June 11, 2022 18 hours ago, Tim-AZ said: I do supply my positive pressure to the inlet side of the final filter from the FASS pump which in turn is supplying that same positive pressure to the caps pump. The fuel is already being filtered better than the final filter so it should never get clogged. I just did this for ease of plumbing and be able to monitor the pressure at that housing. Although supplying the outlet pressure of the FASS pump to the INLET of the final filter is the correct way to plumb the system, you only know the pressure at the INLET to CAPS pump if you are measuring the pressure AFTER the final filter and at the INLET of the CAPS pump. I agree it's unlikely that the final filter will become clogged before the two "primary" filters of the FASS system, but you DO NOT know the inlet pressure to the CAPS pump unless you are measuring the pressure AFTER the final filter and at the INLET to the CAPS pump. Imagine a final filter becoming clogged, but you are measuring the fuel pressure at the INLET to that filter...You are not measuring the pressure at the INLET to the CAPS pump, which is the most important reading. My remote pressure gage is reading the OUTPUT of the final filter, i.e. the inlet pressure to the CAPS pump. It has been well over 10K miles now since I replaced an inlet filter on the FASS pump, but when it began to clog, I could see the decrease in the WOT pressure AT THE CAPS PUMP, and that was my "early warning" system that a fuel filter change was in the immediate future. If I have misunderstood your post, please correct me, and do not take offense. Link to comment Share on other sites More sharing options...
timaz996 Posted June 11, 2022 Share Posted June 11, 2022 Van, here is a picture of the gauge mounted on top of the secondary filter housing. Is this measuring before or after the filter? Tim Link to comment Share on other sites More sharing options...
tmw188 Posted June 11, 2022 Share Posted June 11, 2022 Yah good question. I guess the only other way would be to T in after the filter manifold. Link to comment Share on other sites More sharing options...
jacwjames Posted June 11, 2022 Share Posted June 11, 2022 You can probably figure out which port (if it isn't marked) by removing both hoses and using compressed air up into the center hole of the filter base. The filtering is from the outside of the filter element to the inside. When I was trying to figure out which of my hoses on my fuel tank were supply and return I removed one from the tank and then from the filter base. I put the end on top of the tank in a large tube. I then "blew" through the hose knowing I'd either blow fuel out the hose or bubbles into the tank. Fuel came out the hose so I knew I had the supply line and moved this to the FASS pump and then put the suction line from the tank to the FASS pump. I did not have an extra port on my tank so I opted to just put the FASS return line into the top of the tank at the vent hole. I used a 3/4" T, put the return line at the top pushing the fuel down, then came off the side of the T with the vent line. The is an anti-spill fitting for the vent hose to prevent fuel from being pushed out and then I ran the vent hose to the top of the compartment before going down the side of the tank. I have not had a problem with fuel spilling. Here's a picture, the blue hose is the tank return from FASS. I had to have one hose made up, went to NAPA and had them make the hose from wire braided hydraulic/fuel hose both for durability and so it won't collapse. On the FAS pump I put labels at each port so I didn't make any mistakes on hookup Link to comment Share on other sites More sharing options...
vanwill52 Posted June 12, 2022 Share Posted June 12, 2022 23 hours ago, Tim-AZ said: Van, here is a picture of the gauge mounted on top of the secondary filter housing. Is this measuring before or after the filter? Tim I'm sorry, but I cannot tell from your pix. But as I remember, you can look at the underside of the filter mounting bracket and tell which port is connected to the CENTER of the fuel filter. I do remember that it was easy to mistakenly put the tapping in the wrong side of the filter mounting plate. To be sure, remove the filter and verify that your hole goes to the CENTER of the filter. Link to comment Share on other sites More sharing options...
Cubflyer Posted June 12, 2022 Share Posted June 12, 2022 On 6/10/2022 at 9:11 PM, vanwill52 said: Although supplying the outlet pressure of the FASS pump to the INLET of the final filter is the correct way to plumb the system, you only know the pressure at the INLET to CAPS pump if you are measuring the pressure AFTER the final filter and at the INLET of the CAPS pump. I agree it's unlikely that the final filter will become clogged before the two "primary" filters of the FASS system, but you DO NOT know the inlet pressure to the CAPS pump unless you are measuring the pressure AFTER the final filter and at the INLET to the CAPS pump. Imagine a final filter becoming clogged, but you are measuring the fuel pressure at the INLET to that filter...You are not measuring the pressure at the INLET to the CAPS pump, which is the most important reading. Van, While I totally agree with this statement, sometimes the effort is not worth the results. My FASS pump system is mounted where the water separator (primary) filter was located and my original lift pump is bypassed with a union with a " 1/8" NPT" port, I mounted my pressure transmitter there. Yes, it is before the (still installed on the side of the engine with it's water sensor still installed) final filter. I'm ok with that knowing that, at least now, I have an indication that my CAPS pump is at least not 'sucking' (fuel or air)... and if the final filter should (which it never should since it is being fed 'polished fuel') clog, the most likely result will not be a CAPS pump failure, but a simple engine shutdown (fuel starvation, not air or water contamination). My pressure gauge indication gives me two pieces of information I never had before..... knowledge that I have a positive pressure on the inlet side of the final filter...ie CAPS pump (vs a suction) and the FASS pump/filter system is possibly in need of service (filter change). If I was to do it over... I'm not sure the effort is worth the result, given the access to a port to install a gauge or gauge transmitter into. Ken Link to comment Share on other sites More sharing options...
timaz996 Posted June 12, 2022 Share Posted June 12, 2022 12 hours ago, vanwill52 said: I'm sorry, but I cannot tell from your pix. But as I remember, you can look at the underside of the filter mounting bracket and tell which port is connected to the CENTER of the fuel filter. I do remember that it was easy to mistakenly put the tapping in the wrong side of the filter mounting plate. To be sure, remove the filter and verify that your hole goes to the CENTER of the filter. My filter housing was already tapped. I just removed the plug and screwed in my gauge fitting. Link to comment Share on other sites More sharing options...
Notn2bars Posted June 12, 2022 Author Share Posted June 12, 2022 Tim, here are a couple of pic of the filter mount. If you take the filter off you can see which way the fuel flows. God Bless, Ed & Sylvia Link to comment Share on other sites More sharing options...
tmw188 Posted June 12, 2022 Share Posted June 12, 2022 (edited) 7 hours ago, Tim-AZ said: My filter housing was already tapped. I just removed the plug and screwed in my gauge fitting. That’s what I was thinking if it’s in the center it’s reading after the fuel has been filtered. That’s reason I believe most are using that particular filter mount that’s in front of the CAPS pump. If you watch Zmotorsports install video that is why he removed and relocated his Secondary filter in a more accessible location because it has the threaded port already on it. I guess without a gauge up front in the cockpit you loose out on reading it under a demand load. Good photos above from We2dynasty Edited June 12, 2022 by tmw188 Link to comment Share on other sites More sharing options...
timaz996 Posted June 13, 2022 Share Posted June 13, 2022 Thank You Ed. My gauge is in the center so the pressure I see on the gauge is going to the caps pump. Tim Link to comment Share on other sites More sharing options...
cbr046 Posted June 13, 2022 Share Posted June 13, 2022 On 6/11/2022 at 9:08 AM, jacwjames said: I did not have an extra port on my tank so I opted to just put the FASS return line into the top of the tank at the vent hole. . . . . I'm not going to say "don't do it this way" but when I did it I was getting intermittent drips coming out the tank vent, but in jacwjames defense my T still had to make a 90d turn into the tank (vent tube was the T part). I didn't shoot the FASS return straight down like he did. . My fear was that it would start coating the bottom / side of the RV. So I T'd into the fuel (CAPS) return line at the fuel tank (fitting to the left of the sending unit). 1.) It's a larger line so the FASS bypass shouldn't present much back pressure on the CAPS return line. 2.) It's at the tank, not near the CAPS, so not pushing fuel a long distance. I'd love to know how much volume the CAPS pump sends back to the tank? I can't imagine it being much. The CAPS is designed to return air also. Still, it make you wonder why they used such a large diameter hose . . . . Thanks vanwill52 for your comments. - bob Link to comment Share on other sites More sharing options...
Cubflyer Posted June 13, 2022 Share Posted June 13, 2022 12 minutes ago, cbr046 said: I'd love to know how much volume the CAPS pump sends back to the tank? Bob, That's EZ if you really want to know,,,,,, disconnect the CAPS return line (at the fuel tank), extend it into a bucket, start the engine.... rev it up, let it idle, see how much is really returned..... Ken Link to comment Share on other sites More sharing options...
vanwill52 Posted June 14, 2022 Share Posted June 14, 2022 4 hours ago, cbr046 said: I'm not going to say "don't do it this way" but when I did it I was getting intermittent drips coming out the tank vent, but in jacwjames defense my T still had to make a 90d turn into the tank (vent tube was the T part). I didn't shoot the FASS return straight down like he did. . My fear was that it would start coating the bottom / side of the RV. So I T'd into the fuel (CAPS) return line at the fuel tank (fitting to the left of the sending unit). 1.) It's a larger line so the FASS bypass shouldn't present much back pressure on the CAPS return line. 2.) It's at the tank, not near the CAPS, so not pushing fuel a long distance. I'd love to know how much volume the CAPS pump sends back to the tank? I can't imagine it being much. The CAPS is designed to return air also. Still, it make you wonder why they used such a large diameter hose . . . . Thanks vanwill52 for your comments. - bob Bob, the FASS pump has a HUGE capacity, compared to what your engine is capable of burning. As long as you provide a large enough return line capacity, it will definitely "polish" your fuel over a period of time. I think mine returns about 85 GPH to the tank. Early on after the installation, I replaced two primary filters (on the FASS unit). The first one was nearly immediately. The second was months later, and I've not replaced one since. I just watch for the CAPS pump inlet pressure to decline under WOT. At light load, the pressure is about 15 PSI. At WOT, it now drops to about 13 PSI. When it gets below 10 PSI at WOT, I'll replace a filter. Even though I now have a 2 Micron final filter (why not?), I expect it will be a very long time before I replace it. Link to comment Share on other sites More sharing options...
tmw188 Posted June 14, 2022 Share Posted June 14, 2022 (edited) I’ve been wondering with the flow of return coming back to the tank from the FASS pump when it’s entering at the top of a T and the vent is coming off the side of the T how good is the tanks venting process really going to be when that flow of fuel is flowing at a pretty good rate down into the top of the T. If anything it seems like it would be pulling air in to the tank by Ventura affect with that vent and not letting the tank itself vent out? Sharing the inlet flow with the CAPS seems like the better choice to me. Edited June 14, 2022 by tmw188 Missing word Link to comment Share on other sites More sharing options...
jacwjames Posted June 14, 2022 Share Posted June 14, 2022 49 minutes ago, tmw188 said: I’ve been wondering with the flow of return coming back to the tank from the FASS pump when it’s entering at the top of a T and the vent is coming off the side of the T how good is the venting process really going to be when that flow of fuel is flowing at a pretty good rate down into the top of the T. If anything it seems like it would be pulling air in to the tank by Ventura affect with that vent and not letting the tank itself vent out? Sharing the inlet flow with the CAPS seems like the better choice to me. When I installed my FASS system I checked the vent, it was OK. I then put the system on and didn't see any problems. But on a trip to the Midwest while I was filling up I noticed that the tank was under a vacuum when I removed the fuel cap, a definite sucking sound. First chance I got I crawled under with a drill and long piece of coat hanger and found my vent hose was plugged by a mud dauber. Clean it out and haven't had a problem since. But this basically tells me that the vent is still functional even with the FASS return coming down from the top. Since there is an anti-spill fitting on the vent hose it only allows air in anyway. So as you are driving it will pull air in as the fuel tank is depleted. Link to comment Share on other sites More sharing options...
tmw188 Posted June 14, 2022 Share Posted June 14, 2022 I see your point Jim, maybe my concern wasn’t really thought thru enough. Where is that anti syphon valve I didn’t really notice one? Link to comment Share on other sites More sharing options...
jacwjames Posted June 14, 2022 Share Posted June 14, 2022 2 hours ago, tmw188 said: I see your point Jim, maybe my concern wasn’t really thought thru enough. Where is that anti syphon valve I didn’t really notice one? The anit siphon is built into the 90 degree fitting going into the tank that the vent hose attached to. If you take it off and look there is a ball bearing that acts as a check valve if the rig turns over. Link to comment Share on other sites More sharing options...
tmw188 Posted June 14, 2022 Share Posted June 14, 2022 Ok I was wonder if it could be in the fitting but didn’t think it was as simple as a SS ball or something. Good to know regardless. Thanks Jim Link to comment Share on other sites More sharing options...
tmw188 Posted June 24, 2022 Share Posted June 24, 2022 (edited) On 6/14/2022 at 12:49 PM, jacwjames said: The anit siphon is built into the 90 degree fitting going into the tank that the vent hose attached to. If you take it off and look there is a ball bearing that acts as a check valve if the rig turns over. Edited June 24, 2022 by tmw188 Wrong interpretation initially. I miss seeing something in your photo Jim so I came back and deleted the post Link to comment Share on other sites More sharing options...
Notn2bars Posted June 25, 2022 Author Share Posted June 25, 2022 Todd, that's the reason I installed the FASS return line on the opposite side of the tank. (Driver side) I removed the original fitting that had a tube that went to the bottom of the tank. Had to unscrew the fitting and bend the copper tube as it was removed. Then installed a larger fitting and the FASS return line, therefore it does not interfere with the tank venting system. God Bless, Ed & Sylvia Link to comment Share on other sites More sharing options...
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