It's 10pm - where's your lift pump?

Scott Langohr · **Posted:** Thu May 22, 2008 8:22 am

It is hard to tell just how big this unit is from the picture but it makes me wonder where something like this would be mounted on the KJ. It looks to big to be put in the spot occupied by the current fuel management head. It already is a job to get a filter wrench on the fuel filter to replace it let alone servicing two filters. It is so tight under the hood that I believe you could spill your beer on top of the motor and it would not show up on the floor under the beast for a week. You could mount it on the frame rail back by the fuel tank I suppose but a skid plate would have to be fabicated to protect the filters from sticks and things while off roading. Skid plates do their job but make servicing a pain. It just seems a little to exposed there.

dieselenthusiast · **Posted:** Thu May 22, 2008 8:38 am

Scott Langohr wrote:

It is hard to tell just how big this unit is from the picture but it makes me wonder where something like this would be mounted on the KJ.

You’re right, it’s very BIG. Not so much the size of the pump as for the size of the filters. I’m putting mine on a JK Wrangler when I do the swap. Todd at DieselToyz has said he can make it work.

gmctd · **Posted:** Thu May 22, 2008 9:05 am

Fact: 15gph lift pump, 60mph, 20mpg = 3gph thru CP3 inj pump, 12gph is returned to 20gal tank, causing some fuel aeration, proven

(Fact: 15gph lift pump, 60mph, 15gph consumed = 4mpg)

Fact: 200gph lift pump, 60mph, 20mpg = 3gph thru CP3 inj pump, 197gph returned to 20gal tank, causing some fuel aeration (snicker!)

Fact: bypass regulation........................

dieselenthusiast · **Posted:** Thu May 22, 2008 6:20 pm

gmctd wrote:

Fact: 15gph lift pump, 60mph, 20mpg = 3gph thru CP3 inj pump, 12gph is returned to 20gal tank, causing some fuel aeration, proven

(Fact: 15gph lift pump, 60mph, 15gph consumed = 4mpg)

Fact: 200gph lift pump, 60mph, 20mpg = 3gph thru CP3 inj pump, 197gph returned to 20gal tank, causing some fuel aeration (snicker!)

Fact: bypass regulation........................

If flow is the problem, then you can have the flow rate turned down for your application. Aeration becomes less of an issue when you have a fuel/air separator.

warp2diesel · **Posted:** Thu May 22, 2008 7:04 pm

The only way you can pump less out of a fixed displacement pump is to divide the flow and in this case send the excess flow back to the tank. Tractor hydraulic systems like John Deere use variable displacement pumps so they can avoid the use of flow dividers and activate several circuits at the same time. Since the common rail is only one circuit the cost of a variable displacement pump is not too smart. Putting on a lift pump that pumps more fuel than what you need will result in aeration, waste of energy on the electrical system, and heat up the fuel even more than the fuel system already does.
1) The Cummins pump is closer to the size needed for our application, aeration, energy use, and fuel heating is minimal.
2) The Kennedy pump has magnetic coupling between the pump and motor, little energy waste, no additional fuel heating, quiet, aeration is not an issue.
3) Carter or Facet pumps pump on demand reducing energy loss, fuel heating; aeration is not an issue.

Buy the FASS, better buy a bigger fuel cooler as well.

Steve

dieselenthusiast · **Posted:** Thu May 22, 2008 7:48 pm

warp2diesel wrote:

The only way you can pump less out of a fixed displacement pump is to divide the flow and in this case send the excess flow back to the tank. Tractor hydraulic systems like John Deere use variable displacement pumps so they can avoid the use of flow dividers and activate several circuits at the same time. Since the common rail is only one circuit the cost of a variable displacement pump is not too smart. Putting on a lift pump that pumps more fuel than what you need will result in aeration, waste of energy on the electrical system, and heat up the fuel even more than the fuel system already does.
1) The Cummins pump is closer to the size needed for our application, aeration, energy use, and fuel heating is minimal.
2) The Kennedy pump has magnetic coupling between the pump and motor, little energy waste, no additional fuel heating, quiet, aeration is not an issue.
3) Carter or Facet pumps pump on demand reducing energy loss, fuel heating; aeration is not an issue.

Buy the FASS, better buy a bigger fuel cooler as well.

Steve

Ah....................that makes sense Steve. So why did Dan at FASS say that he could reduce the flow rate if his pump is a fixed displacement?

warp2diesel · **Posted:** Thu May 22, 2008 8:42 pm

Business Owners all have one thing in common, they need to sell to survive. If he can sell you a fuel supply lift pump designed for a 600+ HP engine to power your under 200 HP engine by diverting the excess flow to the tank, he has your money. Since some of the Cummins pick up engines can be cranked up to 1000 HP the FASS pump has an application for these owners.
Engineering costs money and hardware is engineering intensive. To generate a new FASS type pump for a CRD would cost a chunk of change for FASS and take a lot of engineering time.
By turning a screw, presto he has reduced the flow coming out of the pump.

If you have plans to have the First 500HP CRD ever and swap out the 1/2 ton running gear for 3/4 ton, beef up the frame, make a new adapter for the rear of the engine to have the Cummins sized belhousing, and have Suncoast custom build up a bigger torque converter; then maybe the FASS pump is for you :idea:

Otherwise select a supply pump that has a better size and your CRD will be happy

A Kennedy pump with a water separator next to it near the tank and return line fuel cooler plumbed up front would be a better investment. Racor makes a fuel filter setup as does Cummins Fleetguard that blows away our stock stuff :idea:

For now, I will run my noisy Carter pump and stock filter head until I use up the Mopar filter I bought before I had the whole thing replaced under warranty.

Why, the next thing my CRD needs is a skid plate that can handle the PML pan I put on my trans.

Steve

gmctd · **Posted:** Thu May 22, 2008 9:26 pm

Bypass regulation - no fuel is blocked, excess of IP demand is returned to the tank via the bypass - that's why the mech cam-driven fuel pumps were so effective:

- low rpm = low demand = low rpm = low output

- high rpm = high demand = high rpm = high output

- only way to do similar with electric motor-driven lift pump is to vary the rpm of the motor according to demand of engine using pwm controller

- current technique is the variable bypass, set to some required pressure, rest is bypassed at full volume back to the tank - motor rpm and resultant pump output is unvariable - adjustable bypass makes the fit.

The pump KD sells is magnetically-coupled, which is another form of regulation: when head pressure is reached, determined by design dynes of force, rotor\impeller stops turning without affecting motor rpm - impeller picks up rpm as volume demand increases

Wobbly · **Posted:** Thu May 22, 2008 10:22 pm

Don't know why "lift pump" became such a popular term for automotive fuel pumps. There are sewage "lift stations", "air lift pumps", and the old-fashioned manual well pumps are referred to as "lift pumps". The in-tank pump is not a "lift pump" since it has zero suction lift. A firewall-mounted fuel pump might conceivably be referred to as a "lift pump", but why?

"Lift pump" does have a satisfying redundancy, though. Might be a weightlifting routine.

gmctd · **Posted:** Fri May 23, 2008 12:52 am

Lift pump is not generally used as terminology for automotive fuel pumps - that is a term for a Diesel fuel supply pump as compared to the Diesel fuel injection pump - lifts the fuel from down in the low tank up to the injection pump, higher in the chassis, or just to the inlet of the IP, wherever that may be

Gassers (patooie!) have a carb so you got a fuel pump

Gassers (ditto!) now have fuel injectors, so you have a high-pressure or injection pump

Even unit injectors on Diesels require the fuel be lifted from the tank to the rail.

Lift pumps for Diesels - fuel pumps for not-Diesels

More accurately, fuel lift pump ..................

Scott Langohr · **Posted:** Fri May 23, 2008 7:38 am

My Cummins lift pump install has been in now for a few weeks. It works as previously reported by others. I could not be happier. The 55-65 shudder has gone. There has not been the slightest air bubble out of the fuel management head. Acceleration is much smoother and the engine is noticeably quieter. It starts quickly and exactly the same every time. It is a stealthy modification that, just by pulling the fuse, can be undetectable without dropping the tank. The truck runs as it did previous to the mod. with the fuse pulled so, if the pump fails, it keeps on running until parts and time allow a repair. Fuel pressure, past the filter, is a solid and steady 9 psi although the guage is under the hood and I can't see it while driving to notice any change. The guage is there to tell me when to change the filter. The first tank of fuel yielded no change in fuel mileage. I am going to disconnect the battery to reset the ECM and see if that makes any changes in mileage.

This pump was designed to supply fuel to a motor that is twice as big as mine and gets about half the mileage as mine. My friend has a '05 3500 with 270,000 + miles on it mostly pulling a 5th wheel with 2 temporary mobil FEMA units to New Orleans and loaded with cedar fence posts on the return trip. Never a problem with his pump (or much of anything else for that matter) His stock pump has pumped a lot of fuel. I have no concerns with it's ability to handle the needs of my CRD.

Thanks GMCTD for pioneering this modification and providing help to us novices and all the members with their pictures and suggestions to refine this install.

bugnout · **Posted:** Mon May 26, 2008 8:13 pm

I got a chance to install a small variable resistor in the fuel gauge line. I filled up and calibrated the gauge to read full, just off the needle stop. I'm going to run it to half a tank and fill up see how much is remaining in the tank. again at a 1/4. I think I have about 40 ohms added right now.

I put about 6 inches of wire on the ends of the resistor, shrink tubed the hole smash and ran it out one of the holes in the carpet under the seat by the front seat support. Haven't found a good spot to mount it permanently. May just tie rap it to the seat support. took me about an 1 1/2 hour to get the seat out again and splice the resistor in. I was going to drop the tank again, but everything is working so well, and I've got too many projects to spend another day on it right now.

For those that don't remember, after my install, the gauge read 1/4 tank when empty, 1/2 tank at 1/4, 3/4 tank when actual was 1/2 and when I filled up it took lots of miles to get it to drop off the needle stop.

MTB_TDI · **Posted:** Mon Jun 02, 2008 10:02 pm

question:

I want to know what I need to do to use my existing harnes and add the two wires to my 06 CRD. Which locations do I need to add the wires too? And do I need to switch any wires around or just add them? It might be pretty obvious when I get into it, but I just want to know beforehand.

bugnout · **Posted:** Mon Jun 02, 2008 10:46 pm

MTB_TDI wrote:

question:

I want to know what I need to do to use my existing harnes and add the two wires to my 06 CRD. Which locations do I need to add the wires too? And do I need to switch any wires around or just add them? It might be pretty obvious when I get into it, but I just want to know beforehand.

The two wires I sent are 6" too short because they came out of an 05 gasser harness. so the first thing you want to do is splice in an extension to make the long enough for your existing harness. I would suggest adding the splice to the end that will be under the rear seat. thats the end with the blade connector and the bare wire. The bare wire will be the ground for the pump. The other two connectors which are female and are identical get inserted into the connector that goes to the lift pump. You could use a sharpie to blacken the wire thats going to be the ground and solder on a ground terminal.

Review the pictures and wiring diagrams you'll find early in this thread to figure out which pins are which. Once your sure how to take the connectors apart and where the new wires are going to go, your next move is to do the install. You have to remove the back seat, and drop the fuel tank to get to the two ends of the harness.

I found that removing the back seat first so you can get to the connector, then dropping the fuel tank builds confidence as you go. Once the tank is out and the connector is disconnected from the fuel sender. just follow it back to where it goes through the floor, pop that weather seal out and disconnect it on the backseat floor. take it to your workbench and start taking the connectors apart so you can get the new pins in. There are great pictures and descriptions on how to disassemble the connectors in this thread so go back and read it all.

It took me the better part of a Saturday to do this project. Want to make sure the tank has as little fuel as possible and you might need some extra hands when you put it back together.

Not sure I've seen a required tools list but minimum would be:
Wire strippers
Soldering iron - I suggest soldering everything
heat shrink tube and/or electrical tape
crimper and butt connectors if you don't want to solder
Socket set
-- 3 different socket sizes to remove the rear seat - 18mm, can't remember the others.
-- 6 bolts to remove the fuel tank skid if you have it
-- 2 bolts to remove the fuel tank strips
-- breaker bar, might need it to remove the 6 bolts for the skid
BFH - Big Hammer and Crow bar to remove the retaining ring that holds the sending unit in

Did I miss anything?

Bill.Barg · **Posted:** Tue Jun 03, 2008 12:32 am

Adding to the list,

My tank top was caked in dirt. It needed a lot of cleaning to get it clean enough to remove the tank sender unit.

I needed some blocks to hold the tank up off the ground once released from the chassis. This prevented undue strain on the semi-rigid fuel lines.

My tow hitch bolts had locktite on them. I did not put any on during re-install, and I would have liked to.

Joe Romas · **Posted:** Tue Jun 03, 2008 6:33 am

Bill.Barg wrote:

My tow hitch bolts had locktite on them. I did not put any on during re-install, and I would have liked to.

I have a hitch also and found that by gently bending the two straps down it was not necessary to remove the two rear bolts :lol:

gmctd · **Posted:** Tue Jun 03, 2008 10:14 am

If you lay up under the rear of the KJ you can see the problem: the tank is molded to create a 'cup' that the tank module fits within - the large ridges are oriented such that the indexed Jeep module is positioned to allow the fuel sender arm max travel within the gap, allowing the arm to reach the bottom wall of the tank - the indexed Dodge module fits such that the arm contacts one of the ridges, limiting travel to 1/4 tank level

Solution: bend the Dodge arm to fit the Jeep tank, or re-index the Dodge module to match Jeep orientation

05infernoCRDL · **Posted:** Tue Jun 03, 2008 11:57 am

bugnout wrote:

MTB_TDI wrote:

question:

I want to know what I need to do to use my existing harnes and add the two wires to my 06 CRD. Which locations do I need to add the wires too? And do I need to switch any wires around or just add them? It might be pretty obvious when I get into it, but I just want to know beforehand.

The two wires I sent are 6" too short because they came out of an 05 gasser harness. so the first thing you want to do is splice in an extension to make the long enough for your existing harness. I would suggest adding the splice to the end that will be under the rear seat. thats the end with the blade connector and the bare wire. The bare wire will be the ground for the pump. The other two connectors which are female and are identical get inserted into the connector that goes to the lift pump. You could use a sharpie to blacken the wire thats going to be the ground and solder on a ground terminal.

Review the pictures and wiring diagrams you'll find early in this thread to figure out which pins are which. Once your sure how to take the connectors apart and where the new wires are going to go, your next move is to do the install. You have to remove the back seat, and drop the fuel tank to get to the two ends of the harness.

I found that removing the back seat first so you can get to the connector, then dropping the fuel tank builds confidence as you go. Once the tank is out and the connector is disconnected from the fuel sender. just follow it back to where it goes through the floor, pop that weather seal out and disconnect it on the backseat floor. take it to your workbench and start taking the connectors apart so you can get the new pins in. There are great pictures and descriptions on how to disassemble the connectors in this thread so go back and read it all.

It took me the better part of a Saturday to do this project. Want to make sure the tank has as little fuel as possible and you might need some extra hands when you put it back together.

Not sure I've seen a required tools list but minimum would be:
Wire strippers
Soldering iron - I suggest soldering everything
heat shrink tube and/or electrical tape
crimper and butt connectors if you don't want to solder
Socket set
-- 3 different socket sizes to remove the rear seat - 18mm, can't remember the others.
-- 6 bolts to remove the fuel tank skid if you have it
-- 2 bolts to remove the fuel tank strips
-- breaker bar, might need it to remove the 6 bolts for the skid
BFH - Big Hammer and Crow bar to remove the retaining ring that holds the sending unit in

Did I miss anything?

Some have said that the wire size of the leftover wires in the Gasser harness is too small to handle the constant current required by the liftpump.

dgeist · **Posted:** Tue Jun 03, 2008 1:06 pm

Joe Romas wrote:

Bill.Barg wrote:

My tow hitch bolts had locktite on them. I did not put any on during re-install, and I would have liked to.

I have a hitch also and found that by gently bending the two straps down it was not necessary to remove the two rear bolts :lol:

Joe/Bill (anyone), do you have any photos of what needs to be removed to drop the tank? I'm fine getting under there and figuring it out but don't have very much time with myself and the jeep in the same place. I did the interior wiring section in about 2 hours last weekend and only need to re-pin the pump connector and add the pump to be done and was hoping to save time in planning.

Dan

Ripster · **Posted:** Tue Jun 03, 2008 1:25 pm

dgeist I did the wiring harness one weekend and the tank when I had another weekend.
Taking my time, removing carpeting on a 2005, removing tank, cleaning tank outside before
removing ring adapter or dirt will fall in tank, etc. Took 3-4 hours, and I took my time, dropped
the straps down, left the bumper area bolts on the straps on. That was taking a bit of time
to figure out the connectors also.

It's 10pm - where's your lift pump?

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