Finishing up FASS install, stupid wiring question

[DownByTheRiver]

This may be a stupid question, but can I trigger the FASS relay to pick up by connecting the coil to the hot for the existing lift pump? I know the stock pump has weird cycles, but I can't really think of a reason I shouldn't. Maybe one of you can before I do something stupid! I'm already using the ignition fuse in the door panel to power my isspro gauges, and would prefer to stay inside the engine bay with this. Lift pump and filter housing are gone. In my searching, I could only find where people are being warned not to let the ECU take the brunt of running the FASS, and to use a relay.

Thanks.

 

[DavidC]

That is the normal hookup.

 

[DownByTheRiver]

That is the normal hookup.

Thank you sir.

 

[DownByTheRiver]

Got everything installed today and only seeing 12 psi when primed...surely this can't be right for a 16-18 psi spring. I've been reading where people are putting washers etc. in the spring to raise the pressure. That is ridiculous for an $800 unit.

I'm also losing prime after it reaches 12 psi...no leaks. I need to do the 5 gallon bucket test I guess, but I'm fairly tired of rolling around in diesel fuel. Furthermore, every picture I see of this system shows a different filter arrangement. Does the water separator go nearest the suction line from the tank on the back of the block, or on the front of the block with the long draw tube? That's not what their instructions or the filters themselves show. Their manual also incorrectly lists the filter you need to crack for priming as a part number not even in the kit (i believe this to be the fuel filter, which should probably be on the front to allow air to push through).

Last time I talked with the their customer service to verify what fittings etc I needed to change from a 12 valve system to a 24 valve system, I was talked to like I was an inconvenience, and was told I "need to look at the manuals". A little disappointed with this purchase so far.

 

[DavidC]

I can't help much as I still have the stock system. What I have read tho pertains to the plastic check ball with the return to the tank. At least after a while they develop a groove in them causing problems but should not be a problem on a brand new system. Is there a way to block off the return and see what happens ?. If that ball does not seat fuel will drain back to the tank causing hard starts.

 

[BigPapa]

What system did you buy?
Where did you get it?
What truck do you have?

 

[JR]

The system will not maintain 12 psi once the pump shuts off. Are you getting any hard start issues?

The primary filter should be inline with the pump. You would need to loosen the secondary fuel filter to prime the system.

 

[DownByTheRiver]

I can't help much as I still have the stock system. What I have read tho pertains to the plastic check ball with the return to the tank. At least after a while they develop a groove in them causing problems but should not be a problem on a brand new system. Is there a way to block off the return and see what happens ?. If that ball does not seat fuel will drain back to the tank causing hard starts.

This is my main concern. I've read about the check ball problems, and that's the only thing I messed with in order to change the spring to the 16-18 psi model. I need to pull the return fitting off tomorrow and see if the ball is still seated. Hopefully it's something that I've done.

What system did you buy?
Where did you get it?
What truck do you have?

The system is a TS-D10-125G for a 12 valve. I ordered it for my 2001 24 valve from XDP, expecting to convert to a p pump, but my lift pump has recently dropped to 10 psi idle. I decided it best to install the 12v system with the components necessary to run at 16-18 psi and connect to the VP44. When I called FASS, they said this was not an issue. Going from the 24v to the 12v system however, is, due to differences in the pump. I did install a bean's micro sump instead of using the draw straw. Also of note, I used a barbed t-fitting from Geno's in order to run my fuel pressure gauge (with 3279 autometer snubber bolt). I used hose clamps on these barbs, because I don't believe them to be push lock fitting. I was very careful not to ham fist the hose clamps on to the push lock hose.

The system will not maintain 12 psi once the pump shuts off. Are you getting any hard start issues?

The primary filter should be inline with the pump. You would need to loosen the secondary fuel filter to prime the system.

I installed the system, bled it and drove out of the driveway. It was sitting at 12 psi until about 200 feet later when I noticed the pressure dropping. I cut the engine off before it reached 6 psi. I got it back into the garage, gave all lines another tightening (didn't see any leaks). I would prime it again (took entire lift pump cycle until I heard the pump noise change), and if I turned the key off, I could watch the pressure drop off. Is this normal operation to lose prime like this? If for whatever reason it is, I don't like the idea of having to bump the starter to completely re-prime every time I turn the truck on. I was in a rush earlier, so I'll be able to take my time tomorrow and look things over, but that's what I got out of today.

Here are two different pictures showing filters in different places. Which one is correct?

https://lgoxkbw0vu-flywheel.netdna-ssl.com/wp-content/uploads/2018/01/FASS_250x250.png
https://fassride.com/wp-content/uploads/2019/02/Signature_Series_95-165_V1.png

Thanks for the help, folks!

 

[DavidC]

The pressure will drop off immediately at shutdown. When the key is turned on the pump will cycle for 1-3 seconds, if you briefly crank without starting the pump runs for 30 seconds, after startup the pump runs constantly. There should be enough fuel in the system to start the truck and the pump plays catch up for a few seconds. If you have difficulty starting then you have a problem with fuel siphoning back to the tank.

 

[DownByTheRiver]

The pressure will drop off immediately at shutdown. When the key is turned on the pump will cycle for 1-3 seconds, if you briefly crank without starting the pump runs for 30 seconds, after startup the pump runs constantly. There should be enough fuel in the system to start the truck and the pump plays catch up for a few seconds. If you have difficulty starting then you have a problem with fuel siphoning back to the tank.

This makes perfect sense...I wasn't sure if it held prime after it was off.

I think you're right, and hopefully it's something I did with the check ball and spring! I'll check it out tomorrow. It started up with a little effort the first time and ran for a few minutes until the pressure started dropping. I never tried to turn it back on after that. It would take a whole (once even two) 30 second bump cycle to re-prime. I chalked the first start up to air in the lines etc.

 

[JR]

Those two pictures appear to be of different pumps? I see one is a Titanium but can't tell the other. The first picture looks correct to me but the block configuration on that Titanium could very well be different and also be correct. I've only had experiences with Air Dogs so can't say for sure.

Can you even install the filters in the wrong place? Air Dog always used to have different threads for the primary and secondary filter so it was impossible to get them wrong. Your manual should tell you the orientation.

If you are 100% sure the wiring is correct and the pump is running as it is dropping pressure I agree, take a look at your ball and spring.

 

[DownByTheRiver]

Finally got back around to messing with the truck. I looked inside the return fitting at the pressure spring, and wouldn't you know it, there's no ball. There is a machined thimble that the spring sits in, so maybe they've changed the design? I also replaced the overflow valve on the VP44 for piece of mind. I doubt it was flowing enough to overcome the pressure from the FASS though.

Going in the morning to get two filters, as I've had these off too many times and it's not worth getting garbage in the engine or pump. I'll start it up and see what it does.

 

[DownByTheRiver]

For anyone wondering, there is a difference in the titanium pump and the titanium signature pump in that the filter locations are reversed when using fass filters on the signature series, but for any aftermarket filters, they'll go on the original locations. When you buy their new filters on an old pump, the new fass filters will go on like the diagram on the filters says. You can imagine my confusion when their filter cross reference lists water separators as fuel filters and vice versa. There is a lot of information that I had to find out through 3rd party videos, etc. I know they want you to keep using these filters, but I also stumbled across a thread where they were passing a rebadged fleetguard filter off as a water separator when it wasn't rated for that. I'll stick with the filters I can look at specs of. I think if I were to do this again, I'd go with a plane jane Walbro, etc.

I did speak with someone with FASS about the low pressure (12psi) from the spring, and he was very helpful and informative. However, one of his troubleshooting ideas was to take out that machined thimble that replaces the ball and sand it to get rid of burrs, etc. That's sloppy machining, which is unacceptable for a unit of this price.

I'm also having trouble running off of my lift pump wiring, but that's not on FASS. My lift pump doesn't run enough with key on only to see any meaningful fuel pressure, so it has to be bumped every time. Otherwise, it takes about 10 seconds to build 10 psi if I key on and start with zero pressure. Wiring to ignition source will fix that.

I think everything is working now, or at a minimum I understand what it will take to work. Thank you guys!