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Lift pump failure theory

11K views 17 replies 9 participants last post by  mray 
#1 ·
I've been hanging around the site for a couple of weeks taking it all in and have a couple of questions in regards to using lift pumps and supplemental filters.

I see where people are concern abt having a lift pump with flow-thru capability in case of lift pump failure, but I've yet to see any concern abt ability of the CP3 to draw thru extra filters and if the lift pump fails.

Has anyone tried measuring the fuel press (or actually the vacuum) the CP3 generates when pulling thru the factory filter plus an extra filter, plus the water separator, plus whatever mechanism separates the air from the fuel (assuming the lift pump has failed)?

What happens when you try sucking fuel thru the air separator without the positive press from a lift pump? Would it suck even more air into the sys?

I like all the positive benefits of the lift pump and extra filtration, but I'm concerned abt what would happen if the lift pump fails. Will it crater the CP3?

Also, some of the aftermarket filters have 2 to 4 times less pore size and higher efficiency. Wouldn't that make drawing fuel thru them even more difficult?

I know I'm probably over thinking this subject but it's causing me a bit of uncertainty with what set-up would be best over all. Maybe I should just move the fuel tank to the roof :thumb
 
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#2 ·
With a fresh BF1212 primary fws filter, a fresh BF7633 secondary filter aft of the JK pump,



and finishing with a fresh PFF50216 Racor tertiary filter in the stock location up front;
2"hg @ idle, no LP powered, baseline.
As it increases toward 5"hg (no LP), then it's time for a filter change.

I was surprised at how well the CP3 did on it's own pulling thru 3 filters, while towing too. Not a hiccup one.

As for the air worries, can't help ya there. Other than to say, "don't aerate the fuel with a fire hydrant spigot and you don't have to worry about removing the air afterwards". :cool:
 
#3 ·
Lift pumps fail, no question about that. BUT, most of us get a new one on the way right away and get it swapped out.

That being said, wouldn't the cp3 benefit from not having to work as hard and the engine benefit from having less water and better filtrated fuel the other 99.9% of the time that the pump is actually functioning?

I wouldn't want a pump that is not a flow through design for when the pump does fail because it would at least allow the truck to be driven.

Just my .02
 
#5 · (Edited)
Hey, another cen Tx Dmax brother!
I dig your set-up. Nice clean install.
The idle data is great. Can you monitor the press while driving?

Express, the FASS system is what I've been leaning towards, so it's good to hear some honest info.
What if you were to install a bypass hose around the FASS sys with a check-valve so that if the FASS fails, the CP3 could draw fuel directly from the tank via the bypass hose? Seems like it would work well, assuming you still have a factory filter.


In regards to air being introduced;
I saw a youtube vid by the prez of FASS showing the system mocked-up. He got into air removal and the damaging effects of air on the injectors. Seems plausible.
Looking at his mock-up, air was being removed at the highest point along with some fuel. It was then routed back to the tank.
If the lift pump shut-off, looks like this set-up would work backwards and suck in air. There may be a check valve built in to prevent that, but I didn't see one.


Blumer; Ur truck looks like it would be a blast to drive on or off road!
I'm not debating if the sys is beneficial, I'm totally sold on the benefits. It's just a matter of configuring the sys.
 
#8 ·
Just my Opinion....

Here's the vid I was referring to.
Carnie act. nono

Artificially stimulating foam, then removing it. Yeah, I guess it works. :rolleyes:

Fuel tank levels higher than an 1/8 tank (as shown) don't slosh like that. Neither does steady highway driving.
Returning unused fuel to the tank is not a free fall waterfall as in the illustration. And normal stock return rates of fuel are nowhere near the volume shown....as it falls to aerate the surface even more.

And while driving down the highway, even under the most extreme load conditions, towing into a 50mph headwind trying to reach 70mph, you still won't even get close to 10gph in consumption. So back to stated earlier,, cycle a huge amount of unused fuel volume, which can abnormally agitate the tank's fuel....and then save the day by removing the air.

Solving a problem created that wasn't there before. Good idea. But far from original. Woodrow Wilson was hoodwinked into signing away our Country's wealth....in an attempt to solve a banking problem created so as to have a solution to the impending crisis....that wasn't.
 
#7 ·
What part of Texas you in
 
#9 ·
I will say that my airdog is definitely a flow through design as I didn't notice that the fuel relay to the pump quit working and drove it for approx. 500 miles with no problems, if you are worried too much about it I would just set up a way to bypass it. I might also add in all the lift pump discussions that you have to take in to consideration peace of mind and a lifetime warranty on the pump.
 
#11 ·
Air Dog II 165, it's not the new Air Dog 4G.
 
#12 ·
I've been running my raptor since 2011, my 05' had 150k on it when I installed it, flooded that truck with 228k on it and have had it on my LMM for 47k miles now. It is noisy these days put still spits out 12 psi
 
#13 ·
Sorry, to revive this.

1) If the CP3 fails will the lift pump be able to push fuel through?

2) If so, is there a CP3 code that pops up?
 
#15 ·
Sorry, for the noob question. Doesn't the auxiliary lift pump pull fuel from tank as well as push fuel to the CP3?
 
#17 ·
So with that being said, wouldn't it be better to invest the money into a CP3 versus lift pump? I understand the lift pump is for preventative maintenance but I would hate to go out and spend $600 only for my CP3 to fail shortly after. Is the CP3 failure even something to consider at 120K miles?
 
#18 ·
Not likely to fail at 120k, the lift pump can add life to the cp3 pump as it supplies it with positive pressure rather than it sucking fuel clear from the tank and through the filter.
 
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