Chevy and GMC Duramax Diesel Forum banner

Status
Not open for further replies.
1 - 20 of 131 Posts

·
Premium Member
Joined
·
163 Posts
Discussion Starter #1
I am guessing it adds more fuel when running hard?
 

·
Confidence Antler
Joined
·
1,997 Posts
There is no fuel pump on our trucks until our injection pump (the cp3), which is on the engine. Thus, the cp3 has to suck the fuel all the way from the tank. When running heavier tunes, the cp3 strains and can't suck all the fuel it needs from the tank. So a lift pump "lifts" the fuel from the tank to the cp3, providing the cp3 all the fuel it needs to supply the desired rail pressure.
 

·
Registered
Joined
·
346 Posts
A lift pump picks up the fuel and feeds it to the cp3, this takes the strain off of the cp3 trying to suck the fuel. It will also keep your rail pressure up when you get into high hp tunes and are asking for a lot of fuel. If you buy something like an airdog, you also have the advantage of having another fuel filter along with a seperate fuel water seperator.
 

·
Registered
Joined
·
346 Posts
damn it, too late :)
 

·
Registered
Joined
·
12,050 Posts
you can have an extra filter, some dont have a filter on them, but yes what they all said. it relieves strain on the CP3 it actually is good for even a stock truck
 

·
Premium Member
Joined
·
163 Posts
Discussion Starter #6
So I was on the right track, Thanks for the answer! :drink
 

·
Registered
Joined
·
4,016 Posts
Not exactly.

The only thing a lift pump does, is provide pressure above atmospheric to give fuel a higher boiling point. This decreases the vapor cavitation that the CP3 otherwise experiences from boiling.

Chilling the fuel would have a similar benefit.
 

·
Its just a worktruck
Joined
·
13,908 Posts
Huh? So you're saying if I have a tune with a 3100 µs pulse, then cooling the fuel will make it not trip a low FRP code and make the CP3 magically pump more fuel? Seriously?

A lift pump will help you maintain FRP when running tunes that demand more fuel. It also takes stress off of the CP3, so they can be beneficial even on stock trucks. An LBZ needs to operate around 24k psi to make max power for example. With no lift pump and a hot tune, you may drain the rail down to 18-19000 psi or less. This will make the EGTs sky rocket because the ecm sees there is not enough fuel and opens the pulse accordingly to try and compensate. Not enough fuel=heat. More than likely the truck will not be able to make shifts as well. A lift pump will cure that ailment. It also helps greatly with throttle response. I know of a few people that picked up .2 or more just by adding a lift pump.
 

·
Confidence Antler
Joined
·
1,997 Posts
Michael, I highly doubt one could chill the fuel enough to effectively eliminate sub-atmospheric boiling. The specific heat of diesel is too high to have a cooler as small and light as a lift pump be effective. It would take something much larger and/or complicated. There's a reason it's been negated via pressure instead of temperature for all these years.
 

·
Received a Hummer
Joined
·
9,628 Posts
Don't know if this matters or not, but it also removes any air bubbles in the fuel, thus delivering more pure fuel......and the fact that I'd rather crawl under the truck to replace a fuel filter than rip a wheel well out :)
 

·
Registered
Joined
·
4,016 Posts
Michael, I highly doubt one could chill the fuel enough to effectively eliminate sub-atmospheric boiling. The specific heat of diesel is too high to have a cooler as small and light as a lift pump be effective. It would take something much larger and/or complicated. There's a reason it's been negated via pressure instead of temperature for all these years.
I agree with 50% of that. :)

The other 50% leans on a visual of the fuel heat exchanger (GM hates spending money), and says remove the cooler and see what happens to pressure on the lift-pump equipped truck.

Diesel, as an aromatic, is very volatile with even small temp changes.
 

·
Confidence Antler
Joined
·
1,997 Posts
I agree, but I'm still saying that cooling the fuel, right now, is not nearly as efficent as a lift pump when it comes to preventing sub-atmospheric boiling.
 

·
Premium Member
Joined
·
163 Posts
Discussion Starter #14
So it seems to me that the Airdog would be the one to get, because of the filters. But, I am guessing I wouldnt need it yet untill I get a trans?
 

·
Registered
Joined
·
347 Posts
Not exactly.

The only thing a lift pump does, is provide pressure above atmospheric to give fuel a higher boiling point. This decreases the vapor cavitation that the CP3 otherwise experiences from boiling.

Chilling the fuel would have a similar benefit.
Huh? I could not disagree more with this statement.
 
1 - 20 of 131 Posts
Status
Not open for further replies.
Top