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

[MFranz]

AirDog

Edge Eze,DTT transmission and AirDog = Rocketship.

Ive been real happy with the AirDog system so far. Pressure Im not sure it was 15PSI but that keeps changing. It always seems to go up even at WOT. I think I need a new gauge.

Take Care

Mike

 

[Kry226]

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???

Superduty's experience (before the CP3 bypass) was that the stock filter canister lid blew at +60 psi. A few suggestions to monitor pressure is to put a FP gauge PRE-FILTER. If pressure drops, that indicates FP problem. If pressure goes up, that indicates filter blockage. Establish a comfortable baseline for the CP3, then monitor fuel pressure to identify filter change interval.



It at least makes sense to me, but I am keeping an open mind to dertermine the best LP set-up. I don't think I'll be retrofitting with a in-tank pump if the stock Carter goes south. So let's keep debating and get this thing figured out since DC has yet to crack the reliable LP code.

 

[99Supercab]

Superduty's experience (before the CP3 bypass) was that the stock filter canister lid blew at +60 psi. A few suggestions to monitor pressure is to put a FP gauge PRE-FILTER. If pressure drops, that indicates FP problem. If pressure goes up, that indicates filter blockage.

Well, your kinda right. What we`re seeing on my dad`s 02 is that the pressure is also going up becuase of the return line restriction. So pressure going up is not only indicitive of filter blockage, but return line restriction too.

 

[99Supercab]

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

Gotcha now. If you`re all stock, you have no need to upgrade, right ? Also, yes, the Walbro does Flow alot of fuel, but thats the point of the bypass.

 

[rbattelle]

Gotcha now. If you`re all stock, you have no need to upgrade, right ?

"Need" is pretty subjective.



-Ryan

 

[RMalone]

"Need" is pretty subjective.



-Ryan

:-laf :-laf especially on the TDR.



But seriously, every man, woman and some kids I know, NEED and I mean NEED a 600hp/1100tq diesel pickup, no doubt. At least I do! Keep talkin' guys my low side fuel supply needs some help.

 

[Kry226]

Well, your kinda right. What we`re seeing on my dad`s 02 is that the pressure is also going up becuase of the return line restriction. So pressure going up is not only indicitive of filter blockage, but return line restriction too.

Understood that return line restriction causes pressure to increase, but it shouldn't vary, and should only be a few PSI in any case. That's why you establish a baseline with a clean filter and watch the pressure. Any increase should be indicative of filter clog, drop indicates LP problem.

 

[99Supercab]

I understand that the return line cause restriction, thus, an increase in pressure. I believe that the problem we are having is not only being caused by the increased flow through the return line, and its inherent restriction, but also by the fact that we haven`t quite figured out the correct size regulator. We are switching to a 1/2" Swagelok becuase we think the Walbro pump is over-pressuring the 1/4" Swagelok we have in there now.

 

[RMalone]

Does Walbro make a 30psi, 100gph pump? Seems like that would be ideal.

 

[lil red cummins]

using a pump that is only capable of putting out 30 psi puts you back to "being near the limit of the pump".



the reason for using a 100 psi CAPABLE pump, and not running it at that pressure, because you use a pressure regulator with it, is to create a level of security such that you are never anywhere NEAR the limits of the pump. this is definate over-kill and should equate to a much longer life at the lower pressure.



would you rather have a cummins pulling your truck or a v-6 gas engine? this is a relative comparison.



if you still desire a 30 psi max pump, there are plenty of pumps that are in that range. remember though that if you plan to run without a pressure relief, you WILL be running at the limit of the pump frequently.



jim

 

[cerberusiam]

using a pump that is only capable of putting out 30 psi puts you back to "being near the limit of the pump".

Thats the point of running a pump that is sized to your application or "limit". Flowing only enough fuel for injection needs plus enough for cooling is what engineering is about.



In this case bigger is not better, more is not better. If 30 psi is enough to provide adequate flow for the needs then 100 psi 3x overkill and all the fuel is going back to the tank with all the problems associated with that.

 

[Kry226]

Thats the point of running a pump that is sized to your application or "limit". Flowing only enough fuel for injection needs plus enough for cooling is what engineering is about.



In this case bigger is not better, more is not better. If 30 psi is enough to provide adequate flow for the needs then 100 psi 3x overkill and all the fuel is going back to the tank with all the problems associated with that.

The pump will not be running at 100 psi, probably closer to 20 psi with regulator and appropriate bypass. The point is to bypass near the IP, letting the IP take only the fuel it needs, while the rest is sent back to the tank.



By the way, what problems are associated with sending fuel back to the tank? You never explained that.

 

[lil red cummins]

Flowing only enough fuel for injection needs plus enough for cooling is what engineering is about.

i agree with the fact that good engineering is about making a product last just long enough to complete the intended life cycle and do it at the lowest possible cost.



the point however, that this search for a better, longer lasting pump is trying to make, is to provide a pump that is way better than anything ever provided by the factory.



if "just adequate" was the desire, then why is the FASS so popular. it is WAY beyond basic and provides a heavy duty, overbuilt product that is very capable of lasting forever. it has higher pressure and flow rate capability than is needed. (no i don't have one).



the people that are having transfer pump failures on the road are not looking for a so-so pump for a replacement. they are looking for something that will NEVER EVER fail again.



in this case over engineering is what some people want - not all, just some.



jim

 

[cerberusiam]

The pump will not be running at 100 psi, probably closer to 20 psi with regulator and appropriate bypass. The point is to bypass near the IP, letting the IP take only the fuel it needs, while the rest is sent back to the tank.

If the pump is capable of generating 100 psi in the system it will be generating the flow to match it. Putting a regulator and bypass reduces what is seen at the CP3 and the excess pressure translated to fuel flow is routed back to the tank. Bypassing the return fuel at the IP is the WORST place to do it for one very good reason, heat soak from the engine. To keep the heat soak to a minimum the bypass should be done away from heat sources.



The second issue is the aeration of the fuel. The more you pump it around the more air that is introduced. Hot fuel and air laden fuel rank number 2 and 3 behind dirty fuel for causing excessive parts wear and performance problems. Given most of our fuel is borderline crap in its best form, adding more problems to it just does not seem the best way to go about solving a problem.

if "just adequate" was the desire, then why is the FASS so popular

Let me clarify, "just adequate" in fuel flow not in respect to the LP. The perfect system would be a bullet proof variable flow LP based on fuel needs at the CP3.



As for over engineering, at what cost is that achieved? Can we ever find a pump that will NEVER fail? That seems to be a bit of "pie in the sky". Don't get me wrong, I am not knocking the Walbro or any attempts to find a better LP system. I am simply pointing out some fundamental issues that seemed to get glossed over and ignored. Consider this; if your LP goes out and kills the CP3 and other parts its under warranty and on DC's dime (if they don't decide bad fuel was the culprit), however, if the CP3 and other parts get trashed due to an unapproved aftermarket LP system you can bet you will be paying the price. Same thing with the FASS, but, the FASS/Airdog addresses some of the issues that could cause failure.



In the end its to each his own decision. For me the FASS/Air Dog seem to be the better choice, even at their price, as opposed to a system that solves one problem and aggravates 2 others even if it is quite a bit cheaper.

 

[99Supercab]

using a pump that is only capable of putting out 30 psi puts you back to "being near the limit of the pump".

In this case bigger is not better, more is not better. If 30 psi is enough to provide adequate flow for the needs then 100 psi 3x overkill and all the fuel is going back to the tank with all the problems associated with that.

I disagree with you on this to a point. The point, in our case is not only to fill our fuel pressure needs now, but to also to allow more even more fueling capablity later on. So while it may seem like overkill now, down the road it could very well be a neccesity.



As for all the fuel going back to the take, so what ?



1. The agruement about inducing more air bubbles into the system makes no sense to me. You can`t tell me that between the cavitating of the fuel in the fuel tank, and the operation of the VP itself doesn`t induce air bubbles into the system anyway. I may be wrong on that point, but my reasoning makes sense to me on this one.



2. Some ppl have stated you`d have to change the fuel filter more frequently, again, so what, its that cheap insurance anyway. Dad already changes his at every oil change anyway.



3. Heat. This one is interesting to me. I do understand everyones arguement on this point, but I think ppl are missing something here. In our particular install, we are not using the stock lift pump at all. We are using the Walbro pump only. Since the Walbro is only running at roughly 25-30% of its capacity, I don`t really see how it is adding that much more heat into the system than was already there.



JMHO here. I certainly can be wrong, and I`m not affraid to admit it. If I`m wrong on any of this, someone please correct me and explain why I am.

 

[99Supercab]

Just to clarify, I am working on my dads truck, which is an 02 with the VP. As soon as we get his figured out, I`m going to add the Walbro onto my truck.



I understand your point on the warranty, and yes it is an important issue for most ppl. My dad`s truck is out of warranty, so its not an issue for him. Mine is still under warranty, but I have a good relationship with my dealer (I do alot of work for them), so I`m not really worried there either.



I guess when it all comes down to it, it all depends on how far each individual is willing to go. Again, to each its own.

 

[cerberusiam]

The agruement about inducing more air bubbles into the system makes no sense to me. You can`t tell me that between the cavitating of the fuel in the fuel tank, and the operation of the VP itself doesn`t induce air bubbles into the system anyway. I may be wrong on that point, but my reasoning makes sense to me on this one

One of the main features of the FASS/AirDog is removing the entrained air from the fuel before sending it to the IP. Why wouldn't it make a diference if more air is introduced constantly pumping more fuel back to the tank? Read some of the posts about the FASS and the effect. Smoother idling, smoother running, quiter operation, better power, and in some cases better mpg. These things have been around for years in the OTR trucks and seem to make a difference. As far as introducing air in the VP, that is supposed to a closed system and if you are getting air in the high pressue side of the IP there are other problems. The extra filtering and fuel delivery are really bonuses in addition to what the FASS addresses.

3. Heat. This one is interesting to me. I do understand everyones arguement on this point, but I think ppl are missing something here. In our particular install, we are not using the stock lift pump at all. We are using the Walbro pump only. Since the Walbro is only running at roughly 25-30% of its capacity, I don`t really see how it is adding that much more heat into the system than was already there.

Where are you putting the bypass? At the IP? or ??? Where are you mounting the pump? I was stated previously the place for the bypass was at the IP, and superdutie's setup does the same. Where do the return lines run? Right alond side the engine soaking up heat as the fuel flows back to the tank. Now lets bypass twice the needed fuel, soak up heat as it returns, and dump it in addition to what the IP is already returning back into the tank. Do you begin to see the issue here.



Like I said before I am not knocking the design, just questioning the wisdom of solving one problem and introducing a couple more.

 

[Concrete Solutions]

The agruement about inducing more air bubbles into the system makes no sense to me. You can`t tell me that between the cavitating of the fuel in the fuel tank, and the operation of the VP itself doesn`t induce air bubbles into the system anyway. I may be wrong on that point, but my reasoning makes sense to me on this one

One of the main features of the FASS/AirDog is removing the entrained air from the fuel before sending it to the IP. Why wouldn't it make a diference if more air is introduced constantly pumping more fuel back to the tank? Read some of the posts about the FASS and the effect. Smoother idling, smoother running, quiter operation, better power, and in some cases better mpg. These things have been around for years in the OTR trucks and seem to make a difference. As far as introducing air in the VP, that is supposed to a closed system and if you are getting air in the high pressue side of the IP there are other problems. The extra filtering and fuel delivery are really bonuses in addition to what the FASS addresses.

3. Heat. This one is interesting to me. I do understand everyones arguement on this point, but I think ppl are missing something here. In our particular install, we are not using the stock lift pump at all. We are using the Walbro pump only. Since the Walbro is only running at roughly 25-30% of its capacity, I don`t really see how it is adding that much more heat into the system than was already there.

Where are you putting the bypass? At the IP? or ??? Where are you mounting the pump? I was stated previously the place for the bypass was at the IP, and superdutie's setup does the same. Where do the return lines run? Right alond side the engine soaking up heat as the fuel flows back to the tank. Now lets bypass twice the needed fuel, soak up heat as it returns, and dump it in addition to what the IP is already returning back into the tank. Do you begin to see the issue here.



Like I said before I am not knocking the design, just questioning the wisdom of solving one problem and introducing a couple more.

I think that this is merely a justifcation on your part as to why you spent

800. 00 on a 120. 00 fix. Just my opinion but from an ME position

I think Superdutys fix is Just Fine. Time will tell.

 

[cerberusiam]

I think that this is merely a justifcation on your part as to why you spent 800. 00 on a 120. 00 fix.

I guess that would fall under the heading of "you get what you pay for"?



BTW, its not one unit its 4, and its planning for 500 HP not stock. I didn't buy $40k trucks expecting to shop at the dollar store and the justification is in quite a few threads right here on the TDR.



Thats my story and I'm sssssstttickin' to it.

 

[99Supercab]

One of the main features of the FASS/AirDog is removing the entrained air from the fuel before sending it to the IP. Why wouldn't it make a diference if more air is introduced constantly pumping more fuel back to the tank? Read some of the posts about the FASS and the effect. Smoother idling, smoother running, quiter operation, better power, and in some cases better mpg. These things have been around for years in the OTR trucks and seem to make a difference.

Ok, I`m not say that the air removal part of the FASS/Airdog isn`t a good thing, I was only stating that I don`t believe its as important as those companies would like you to believe it is, thats all.

As far as introducing air in the VP, that is supposed to a closed system and if you are getting air in the high pressue side of the IP there are other problems. The extra filtering and fuel delivery are really bonuses in addition to what the FASS addresses.

The fact that it is a closed system isn`t relevant here. Yes, it is a closed system, after the lift pump, but not before it. My point was that there is air in the system from the fuel sloshing around in the tank.

Where are you putting the bypass? At the IP? or ??? Where are you mounting the pump? I was stated previously the place for the bypass was at the IP, and superdutie's setup does the same. Where do the return lines run? Right alond side the engine soaking up heat as the fuel flows back to the tank. Now lets bypass twice the needed fuel, soak up heat as it returns, and dump it in addition to what the IP is already returning back into the tank. Do you begin to see the issue here.



Like I said before I am not knocking the design, just questioning the wisdom of solving one problem and introducing a couple more.

Our bypass is at the VP inlet, just like SD suggested. You do make a very good point and I do see exactly what your saying. But we routed our bypass away from the engine, specifically because we didn`t want it near the engine. Yes, we will have more flowing through the VP`s return, but that 5/16th`s metal line isn`t gonna flow that much anyway (which may be part of our problem to begin with)



I don`t want to start an agruement, I`m very open to any and all opinions here. Any relevant info on this subject could yield a low cost alternative to the FASS/Airdog system.