How much fuel pressure does the CP3 need? What are you guys using for lift pumps?

[Smokey 01]

I believe with a Fass you put in a new pickup in the tank and the stock pump stays in place.

 

[Froadin]

Does anyone know how much restriction the new filters have? The 2nd gen is about 5 psi of restriction for just the filter. Figured the new one would be similiar, but not sure.



Btw, doesn't the FASS create too much pressure then? If the injection pump only wants 10 psi and 45 gph, the FASS is way over doing it. Which would be creating too much extra fuel pressure / heat. Just thinking out loud, and still trying to figure out the 'perfect' transfer system.



Thanks for the help, it is really helping me narrow down my choices.

 

[steved]

Does anyone know how much restriction the new filters have? The 2nd gen is about 5 psi of restriction for just the filter. Figured the new one would be similiar, but not sure.



Btw, doesn't the FASS create too much pressure then? If the injection pump only wants 10 psi and 45 gph, the FASS is way over doing it. Which would be creating too much extra fuel pressure / heat. Just thinking out loud, and still trying to figure out the 'perfect' transfer system.



Thanks for the help, it is really helping me narrow down my choices.

The FASS is "adjustable" in a couple increments... 12, 15, 19, and 25 psi. It is determined from the pressure spring holding a check ball located under the return line fitting to the tank. FYI, if you by a FASS, make sure you order whatever spring pressure you want as they tend to be assembled with whatever one is handy (mine came with a 25psi spring and was only a FASS 95/150... not a true 150).



The FASS is flowing WAY more fuel than the IP needs, but what the IP doesn't need is returned by the FASS to the tank (more is better than not enough in this case, the excess fuel isn't just forced through the IP if that is what you are thinking). And being the FASS is "adjustable", you can more or less customize it to what you pressure need/desire.



steved

 

[Froadin]

Steved, thanks, I wasn't sure about that.

But if I ran a 12 psi spring, and I turn my box up to 5, I stand a high chance of dragging it too low on pressure/fuel?

Besides, it seems like they are getting a lot closer on the VP44 for determining that the extra heat of the fuel drastically shortens the life of the IP. I can't see how the CP3 would be any different in this case as it still uses the fuel for cooling, and the more you recirculate the fuel, the more heat you are putting into it.



How does the RASP compare on this point? I know it flows more with RPM, but it also seems like it is overkill in a bad way.



BTW, just so you know, I am working on a design to fix these transfer pump issues for the 2nd gen. It is a different approach then anything I have seen, and I believe it would work perfectly for the CP3 as well. But I have to know the perfect ideals for stock and modified.

But if just getting a FASS is more cost effective, I might not bother with the 3rd gen setups. Seeing as I have both, I do have an interest in taking care of both systems.



Thanks again.



Ed

 

[steved]

Steved, thanks, I wasn't sure about that.

But if I ran a 12 psi spring, and I turn my box up to 5, I stand a high chance of dragging it too low on pressure/fuel?

Besides, it seems like they are getting a lot closer on the VP44 for determining that the extra heat of the fuel drastically shortens the life of the IP. I can't see how the CP3 would be any different in this case as it still uses the fuel for cooling, and the more you recirculate the fuel, the more heat you are putting into it.



How does the RASP compare on this point? I know it flows more with RPM, but it also seems like it is overkill in a bad way.



BTW, just so you know, I am working on a design to fix these transfer pump issues for the 2nd gen. It is a different approach then anything I have seen, and I believe it would work perfectly for the CP3 as well. But I have to know the perfect ideals for stock and modified.

But if just getting a FASS is more cost effective, I might not bother with the 3rd gen setups. Seeing as I have both, I do have an interest in taking care of both systems.



Thanks again.



Ed

The difference between the FASS and a OEM system is the FASS has 3/8 line (no restrictions). It also has whatever pressure at 95gph (or 150gph for the 150)... it will draw down slightly at first then gain back fairly quickly.



I have not seen anything that indicates the FASS causes the fuel to heat up.



I do not know that much about the RASP, other than it looks fairly complicated to plumb up, relys on the OEM lift pump for startup, has a smallish belt, etc. It wasn't for me.



steved

 

[MFalkinham]

There has been some lengthy and intense discussion of lift pump solutions recently over on dieseltruckresource.com. Check out this series of threads... .

http://www.dieseltruckresource.com/dev/showthread.php?t=88136

I need to come up with a better lift pump setup before embarking on a road trip this summer. I'm tempted to try Superduty's Walbro setup rather than going with the FASS. I like the lower cost, the fact the Walbro is cooled by the fuel, and the CP3 bypass feature his design uses. I'm thinking of installing it in steps by first fabricating the CP3 bypass line and then actually installing the Walbro.

- Mike

 

[Froadin]

If the FASS, or ANY pump that uses a bypass, pumps too much fuel, then all the extra fuel is being heated by the pump. This is both wasted energy, and extra heat.

It also shortens the lifespan of the pump.

 

[steved]

And in the real world, how do you avoid this... even the above post indicates pumping more fuel than needed.



Although not ideal, it is almost needed to supply ample volume at all times to the IP.



steved

 

[cerberusiam]

And in the real world, how do you avoid this

First, by not putting the biggest baddest pump you can find in there pumping way more fuel than is going to be needed by even a 500 hp engine. Second, by sizing the pump by the pressure it will achieve. Pressure is still our best indication of the flow that is available so given the stock fuel lines 10 to 15 psi seems to be good but 60 psi would seem to be high.



The CP3 is going to return a certain amount of fuel all the time, but by passing the excess flow at the pump it is going to be dumping a lot more heated aerated fuel back into the tank. Thats 2 of the design problems with the Walbro setup that superduty has come up with. The FASS by design also returns a certain amount of fuel all the time plus the excess that is being pumped, but, it is doing it away from heat soak in the engine compartment and also under a lot less pressure. Less pressure and its design leads to cooler fuel with less air in it being returned to the tank.



Not to take away from superduty or anybody else that designs a working system, but there is a lot more engineering into the FASS and Airdog than just pushing as much fuel as possible and returning the excess. FASS and Airdog have been around for a bit and proven their usefulness, design, and results.

 

[Froadin]

Right, there isn't a need to push way too much fuel just to solve a problem.

The key is not only to have to proper pressure and volume, but to maintain that under all conditions. And for all different levels of HP.



Btw, even though the FASS isn't near the big heat source, the pump itself is wasting energy and putting heat back into the system. It may seem like a small deal, but we also have people out there putting fuel coolers on their trucks. And the best way to cool the fuel, is to not put the heat into it in the first place.



The IP will always want a certain amount of extra fuel for cooling purposes, but that is pretty easy to take into account.

I agree that pressure is a good gauge to use to monitor the system, but getting a properly matched system in the first place would keep from going overkill. Especially when overkill is a bad thing.

 

[rbattelle]

I think that "Superduty's" idea of running a bypass line between the inlet and return sides of the CP-3 itself is pretty clever. The only problem I have with it is there's not way to monitor whether the pump quits on you (since there'd basically be 0 pressure in the system).



I have a PWM (Pulse-Width Modulation) arrangement on mine that's not being used anymore since I switched to the Holley Blue. In my personal OPINION, the Holley Blue produces *almost* ideal flow to the CP-3 for stock or very mildly modified trucks. It's under 100 GPH, and under 15 psi.



PWM would be a great way to vary LP supply volume and pressure with RPM or as a function of fuel box setting. Such a circuit wouldn't be hard (or expensive) to arrange if you're decent with electronics.



-Ryan

 

[MFalkinham]

Superduty admits in his posts that the Walbro model he used was overkill, and that he had to use either the bypass line or a regulator to keep from blowing the cover off the filter bowl. Smaller Walbros or other brand pumps are readily available and perhaps make more sense.

His point was that the pump he uses is liquid cooled, which he feels is desirable. I find it hard to believe that such a small lift pump would put more heat into the fuel than it already picks up by traveling into the engine compartment and through the CP3. Engine coolant gets up to 200 degrees and can still cool an engine, so why is fuel any different (especially with up to 35 gallons of it available)?

 

[Froadin]

Engine coolant at 200 degrees is fine for the engine, but I know the VP44 wants a MAXIMUM fuel temp of 165 degrees. I haven't found these numbers for the CP3 yet, but I can't imagine they changed it all that much.

Also, the heat gets into the electronics, which is what really suffers from the extra heat.



Btw, I am not saying the remote pump will put that much heat into the fuel. I am just saying that when you are taking steps to remove heat from the fuel, the first step should be to stop putting the heat in there in the first place. The FASS makes a huge improvement over the stock setup, without a doubt at all. But if the FASS didn't have to bypass as much, wouldn't that be even better?

 

[MFalkinham]

Fair enough, Froadin. I have no idea if heat will be an issue, but it's good we are all thinking this through. By the way, Superduty is reading these threads and is responding to specific points over on DTR.

We need some beta testers on this, so I'm going to try the Walbro pump and see how it works out. I'm going to save all of my stock hardware so I can go back to OEM if I don't like the results.

 

[rbattelle]

His point was that the pump he uses is liquid cooled, which he feels is desirable.

I thought the point was to keep the fuel cool? If you're using the fuel to cool your pump, then you're heating up the fuel! I suppose a fuel cooler could be plumbed easily.



I would prefer to run an inline style pump for reliability's sake (no need for a seal between the drive motor and the pump body), but no one makes one in a range of flow rates and pressure that I'm willing to try.



-Ryan

 

[GOT-Torque]

Quick question for those with a FASS setup, does this replace the lift pump mounted on the fuel filter housing as well as the hard line from the fuel filter housing to the injection pump? Or does it just pump thru the stock lift pump and hard line?



This question doesn't apply to those with the factory intank lift pump.

 

[steved]

Yes, replaces everything from the tank to the CP3/VP44.



steved

 

[99Supercab]

I thought the point was to keep the fuel cool? If you're using the fuel to cool your pump, then you're heating up the fuel! I suppose a fuel cooler could be plumbed easily.



I would prefer to run an inline style pump for reliability's sake (no need for a seal between the drive motor and the pump body), but no one makes one in a range of flow rates and pressure that I'm willing to try.



-Ryan

The Walbro will operate comfortably at 60-80 PSI, how much more flow do you want, lol. Also, the Walbro is an inline pump. Here`s a link that has a flow chart for the Walbro pump :



http://cgi.ebay.com/ebaymotors/ws/e...&item=8027630831&rd=1&sspagename=STRK:MEWA:IT

 

[JStieger]

I think Superduty's other point is that when you're running the Holley or whatever you're running it at the top end of its pressure rating. By using the Walbro, for example, you're running it so that it is barely breaking a sweat.



I was thinking "a bit" about doing this mod too. I have enough spare banjo bolts and then just need to buy the pump and regulator w/ return to make this happen.



Just set the regulator just ahead of the CP3 to 10-15 psi and you'll have more than enough volume to feed the CP3 with the remaining fuel going back to the tank on the return. The only thing that still confuses me is that if the pump is rated to 60 psi, when will it actually output this pressure and blow fuel everywhere???



How much fuel does one need for 500 HP + cooling/lubricating the CP3? What is the BSFC our the ISBe?

 

[rbattelle]

The Walbro will operate comfortably at 60-80 PSI, how much more flow do you want, lol. Also, the Walbro is an inline pump. Here`s a link that has a flow chart for the Walbro pump

You got me backwards. I meant inline pumps flow WAY TOO MUCH! My engine is stock, it sure as heck doesn't need 60 psi or 200 GPH!



I'm happy with 11-12 psi and <100 GPH.



-Ryan