I know that some say you need them and some say you dont. How do you know if your fuel system isnt getting enough fuel? I think I want to add one. What does everyone have and what is working and what isnt? Thanks

The thing that I have noticed about this subject is some people are adding pumps that are rated to a lower HP than they are already making. The numbers I have seen show you need at LEAST 140gph (preferable 180+) to reach the HP numbers that people are making with NO lift pump. How many people add filters that can't flow at this rate, or pumps that might keep the filter working better at part throttle, but can't keep up for the full 1/4 mile. And with the load and duration being less on a dyno, the symptoms might never show up except at the track. Edited by: Amric

Time will tell if we REALLY need a lift pump, but if we do watch out 'cause Tomac is pretty darn quick without one...

Amric why do you say you need 140gph to make x (how much) hp. I have only seen pumps rated in hp for gas or alchohol applications but I may have missed the diesel ones. For any pump to be rated for X hp is really kind of ridiculous because you have to take a lot of other factors into consideration other that hp output.

CPMac


I am not here to get on your case(done with that). If you are looking to make the most horsepower, what other considerations do you suggest other than making more horsepower and how to get it?(this is not a flame). This is my thought; mayby some programs use fuel to get what they need, mayby others do it differently(cant imagine how with a diesel). What else is there besides, boost, fuel,timing, air(in and out)? ok, in mtomac's case weight because he has a race truck(not a flame mike)


mike

That's pretty much all there is to it Mike. A lot of fuel at the proper time with enough air to burn it. But there are a lot of different way's to achieve it.


I have done a little research on the fuel system and what I have gathered is nothing close to what Amric said and that is why I asked him. But on everything else I understand what he's stating. I haven't ever seen a hp improvement on any dyno whether it be a load dyno or a dynojet with a lift pump but driving and 1/4 mile I can show you a difference. Heck when I made 592 rear wheel the inlet screen of my pump was so plugged it wouldn't draw fuel 1 ft vertical by itself but I didn't hurt my hp that day either.

Speaking of dynos vs. 1/4 miles. Has any one done the formulas to see how much power it takes to motivate 7Klbs. at 12 seconds? Including a less than stellar drag coeficient. Seems to me like it would take about 1500 foot pounds? CPMac, what lift pump do you use for racing? Where is it at in the system?

I use a Holley red and it is on the framerail at the tranny. The bad thing about the formulas you find for power to e.t. calculation is they are setup for a different hp to tq relation so therefore aren't alway accurate.

The pump on the FASS filter is rated at 140GPH and 12 to 15 PSI. Would this be considered an adequate lift pump?

mike,

The minimum weigh for the DHRA Pro Street class is 6200# with one turbo and nitrous. I wish I could get my truck that light. BTW I drive my "race truck" every day and tow 20000-26000 combined regularly during tractor pulling season. I dragrace, truck pull and play in the sand dunes in between with my "race truck"

My fuel system is completely stock.

i dont know why these trucks are so inconsistent but from what i have seen and tested if you check out 3-4 trucks fuel system they all react differently,maybe tomac and bmdmax have those types,

Anyone running 450+ rwhp can benefit from a properly set up lift pump.

The pump on the FASS filter is rated at 140GPH and 12 to 15 PSI. Would this be considered an adequate lift pump?





Fuel pumps are like pressure washers, and most any other pump. They are rated for flow and rated for psi, but what is often overlooked is what the flow rate is AT a given psi. In the case of the FASS I'd say the 140gph is free flow or 0 psi.





Adding a lift pump is doing basically the same thing as the FASS and other such air elimination systems are claiming...

In order to "see" if you need a lift pump ... you need to measure the inlet fuel pressure. This is where the Bosch system takes over and tries to accomplish whatever your program is telling it too. If there is 0-1 psi or less, then the high pressure pump can not pressurize the fuel rails to the proper level which will throw off the amount of fuel trying to be delivered to the injectors.


Some trucks may need one sooner than others due to the plumbing differences ... Nicktane, Pre-OEM, Post-OEM, added water seperator, half plugged filter etc..... But the key is to provide the Bosch high pressure pump with clean, pressurized fuel.

In order to "see" if you need a lift pump ... you need to measure the inlet fuel pressure. This is where the Bosch system takes over and tries to accomplish whatever your program is telling it too. If there is 0-1 psi or less, then the high pressure pump can not pressurize the fuel rails to the proper level which will throw off the amount of fuel trying to be delivered to the injectors.





http://www.dieselplace.com/forum/smileys/Confused.gifBy your definition, ALL DMaxs will need a lift pump. The system from the injection pump back to the fuel tank is a vacuum system with 0 psig or less any time the engine is running. The Bosch system seems to properly pressurize the fuel rails and perform its function at 0 psig or less all the time!


ON EDIT: I think you're talking about the pressure between the low and high pressure portions of the fuel pump? That's also controlled by the fuel pressure regulator - which may need to be replaced before opting for a lift pump.http://www.dieselplace.com/forum/smileys/Ermm.gifEdited by: Idle_Chatter

WHERE ARE YOU GUYS WITH THE LIFT PUMPS GETTING YOUR POWER SOURCE FOR THE PUMP?? ARE YOU PUTTING IT TO A POINT THAT GETS "HOT" WITH THE KEY ON?? OR ARE YOU WIRING IT UP WITH A TOGGLE SWITCH?

On my 93 6.5 the oil pressure switch that controls the lift pump went out every 10-15,000 miles and the first time I drove it all summer before getting it fixed.


The tech said some trucks could suck the fuel past the lift pump but others quit running.


Could be same difference here, some need the extra fuel/lift pump and others don't.


On one of the 01 I got some bad fuel and got a limp mode, had to restart and drove it to the dealer w/ the 15,000# trailer.


The put the whole rig in the shop and put the scope on it and revved the engine and it showed the fuel pressure the computer wanted and what the max pressure was.


This was how the figured the filter was plugged, ran fine afterward.


I would think that if u don't supply enough fuel for the motor it would go in limp mode and set a code too, unless the boxes are fooling the computer.





BTW my 525 cummins and our other big rigs don't have lift pumps at the tank and they do fine.

nut i got mine run into a hot fuse on a piggyback double plug that gets fire when the key is turned on

On my 93 6.5 the oil pressure switch that controls the lift pump went out every 10-15,000 miles and the first time I drove it all summer before getting it fixed.


The tech said some trucks could suck the fuel past the lift pump but others quit running.


Could be same difference here, some need the extra fuel/lift pump and others don't.


On one of the 01 I got some bad fuel and got a limp mode, had to restart and drove it to the dealer w/ the 15,000# trailer.


The put the whole rig in the shop and put the scope on it and revved the engine and it showed the fuel pressure the computer wanted and what the max pressure was.


This was how the figured the filter was plugged, ran fine afterward.


I would think that if u don't supply enough fuel for the motor it would go in limp mode and set a code too, unless the boxes are fooling the computer.





BTW my 525 cummins and our other big rigs don't have lift pumps at the tank and they do fine.








The key to the oil psi switch is to switch the control side of a relay, and NOT carry the pump current across the contacts. That, I believe is why the 6.5 OPS was such a problem.





In the case of the plugged filter, the dealer could check that much more easily with the gauge that plugs into the factory test port.

If your OEM filter gets plugged, there can be enough restriction that the IP cannot provide the commanded pressure and it will result in an SES light, code and limp mode.


It happened to me and it was very sudden, on a hill. I think it is a safety issue to cut power on a vehicle when you could potentially be towing up a hill. They should have a warning light come on at some point before you hit the limp mode, so you have a chance to replace the filter at your convenience, rather than at the side of the road when you're dead in the water.

Amric why do you say you need 140gph to make x (how much) hp. I have only seen pumps rated in hp for gas or alchohol applications but I may have missed the diesel ones. For any pump to be rated for X hp is really kind of ridiculous because you have to take a lot of other factors into consideration other that hp output.


I did base this post on my knowledge of gas motors, and do not claim to be a diesel expert by any stretch of the imagination. Afterwords, I wrote an e-mail to Holley asking them what GPH I would need to make 550rwhp 700fwhp. I was very suprised when I got there reply of only 160GPH.


I know that mtomac is making his power on the stock fuel system which is EXACTLY my point. Could it be that people that are putting on secondary filtration, are restricting the stock fuel system enough to need a lift pump to counteract the increased restriction. I'm not saying this is the wrong way to go, as everyone agrees secondary filtration is a good thing if power is not sacrificed. It just seems that before this thread, there was not enough discussion about the flow rate of these secondary filters, or lift pumps.


It makes me wonder what the flow rate of the factory low pressure pump is. If I was getting a lift pump, I would want it to meet or exceed the factory low pressure pump GPH so as not to cause a restriction.


JMO

I know what the factory low pressure pump flows and it is nowhere near 100 gph. It takes less diesel than gas to make the same hp. Any addition to the stock fuel system could be a restriction so it needs to be taken into account, but the stock fuel system will always move most of the fuel that is needed so depending on additional filters and such would determine what rate lift pump would put you back to the required fuel supply.