Lift Pump Swap

[Paveltolz]

Finally putting the AirDog back on.

I've been running an off the O'Reilly's shelf Lift Pump for a few years. My 'Diesel Site' had gone Tango Uniform while on the road coming back up to Utah from AZ. Cross the border, Zero fuel pressure. Fortunately, I was able to do a quick diesel bath swap with loaner tools. Which was ironic given the AirDog DF-165 I'd been running had done the same thing a few months before in Flagstaff. I love AZ, raised there, so these and other instances with the Touareg have really got me dreading the region.

PureFlow honored their warranty and sent me a new motor but with all the other issues the motor was suffering (suspect IP, Injectors, hobbs key, and valves), I just didn't want to put it in. Once the truck was sorted out, I was just enjoying it and doing simpler things though the LP swap was on the long list of 'Things' I had put off. The near zero fuel pressure under hard acceleration wasn't concerning given I was only driving it occasionally and rarely put the spurs to it.

However, having kicked the Touareg to the curb, the truck is now my daily driver. That and we just did a road trip with the numerous long pulls on the hills I-84 between UT and WA coast provides. Zero fuel pressure IS a big issue.

I got all the parts assembled from various boxes and shelves. Looked up the instructions from PureFlow (they have a 6.5 specific set up now whereas mine was 'adjusted' from a Duramax kit).

The old hoses were a no go. The ones from the kit are all 1/2" and since the fuel lines from the tank to the LP are 3/8" I couldn't understand what the point was for necking up to and back down from 1/2" other than, you know, Duramax.

Besides, I'd replaced the tank and along with the lines to the LP and LP to IP trying to sort out motor issues so, everything already on the truck was much newer than these.

I hated the 'push lock' hose connection system given the luck with GM oil lines. Here's the old install with provided lines and connections.


I removed the push lock fittings with the idea to use -6AN in the future...if ever.


With the motivation on simmer, it was time to go under the truck....

 

[Paveltolz]

On Edit (too late to edit above), here's a better look at the pump mocked up with the provided PureFlow hoses and push locks.



Going back to 2013, The main issue with my installation was making the stock mounting hardware work with the 2 ½” deep ‘C’ Frame on the truck. There was/is a need for an additional 1” – 1 ½” spacer to fill the gap between the mounting hardware and the pump’s bracket. By 2024, AirDog provides an upgraded kit for the 6.5L Diesel equipped GM series trucks which has simpler hose fittings ( -6AN?) AND they provided spacer for mounting the pump inside the rails.

But, in 2013, I had to come up with my own plan. On to the Drawing Board
Measurements were taken and findings translated to paper.

AirDog’s provided Mounting Plate ("Bracket to Frame in the drawing) measured to cut to fit inside the 7 ½” frame.

The original project only needed the short section on the right.

Spacer.
A suitable spacer material with the strength and durability to meet my requirements was found in a galvanized piece of square stock such as one would use for a sign post.

The real bit of serendipity was the holes in the square stock lined up perfectly with the holes in the plate for attaching the pump's bracket. Gotta love those little breaks in projects.

Cut to size and fitted to the mounting plate and leaving the top two holes for mounting the assembled pump on the frame. Two pieces of threaded stock were used with four each nuts to maintain the spacing between the square stock. The threaded stock was trimmed so the four mounting bolts holding the pump backet to the mounting bracket (three shown below) would pass through cleanly.



All parts assembled for fitment confirmation.


Initially, I figured the pump would fit in the same location as the OEM Lift Pump...yeah, not so much....

 

[Paveltolz]

Location Location...As I was saying, Initially, I’d planned to place this set up in the same location as the stock lift pump. In fact, that's the way I remembered it but, with the torsion bars blocking clearances for the filters, I obviously had to adjust things ‘a little more to the left’ and placed it behind the torsion bar frame cross member. The thought of adapting the PureFlow ½” lines to the OEM fuel lines from the tank was never an option at the stock LP location anyway and, had it been, it was no longer an option (for 2024, they ask you to cut the steel line making a retro-fit to OEM lift pump a new project). But, I made things work and it worked fine until it didn't. Fast forward to 2024.

So, I'm under the truck, tryin' to remember just where I'd actually had this thing located in 2017-ish. I had to go back to old pictures and looking for the two holes i'd drilled for the mounting plate to fit. Once that was done I tried fitting the pump and couldn't understand how I'd gotten it in there in the first place. The top of the pump was pushed up against the cab floor and the bolt holes in the frame and the bracket were off just enough. This pump is heavy w/o the full filters and the fun meter is pegged at zero.

I wrangled it in but, the wires on the new pump were pinched against cab floor.
Memory cells kicking in and I remembered the pump being very noticeable both audibly as well as it could be felt in the cab. Ah ha. I wonder if the old one failed because I failed to notice the wires were too close/in contact to the cab floor. Live and learn.

I pulled out the 'scrap' pieced of mounting plate (almost tossed that thing a month ago) and did some comparisons.

By using the one on the left (which also fit perfectly inside the 7" frame rail) and running just one Grade 10.9 through the lower hole in the plate, I could gain the clearance between pump and cab by 1/4 inch. Saves not having to drill two more M-10 sized holes or oval out the existing ones. An added bonus was my fuel line to the LP would now reach since I was removing the Diesel Sites filter (vs. the FFM) at the front of the engine. Yeah, I did have to trim back the feed line from the tank but, it was a rubber line vs. the braided steel bling looking crap I'm into running forward.

Lines.
For the tank to pump feed line, I trimmed off the now excess, inserted a -6AN 45* twist loc fitting and secured with a hose clamp and job done.

For the return to tank line, I utilized thisRussell Performance 180* -6AN twist loc w/ a larger arc.

I used a new rubber diesel rated hose and ran it back to the old 1/2" hose still attached to the fuel filler neck. I utilized a two-sided brass adaptor to make the conversion to 3/8". It's the top fitting in this mock up picture. The others were considered and discarded. Ignore the brass fitting on the right, this isn't the hose I used.

 

[Paveltolz]

So, by now some of you are thinking, 'Didn't he cover this crap years ago?' Yes, guilty but, it was buried in an very long thread. Since its a re-install with some lessons learned, you with better memory get to suffer.

Power to the Pump
The harness is straight forward. At least, it is now. Grounded in the engine bay, 12v power through a fused relay connected to one of the auxiliary power posts on the Under Hood Fuse box and triggered by Key On power through an adapt-a-fuse in the box but, not in place yet.


So, it is in and I'm done for the night.


Tomorrow (Yes, mother's day, got it. Spousal Unit is sick so I've been playing nurse and maintaining isolation so I can justify hiding in the garage for periods of time).

- I'll disconnect the IP feed line and extend it to a fuel jug, power it up and clear out the air, especially the empty line between the pump and the tank. Both of the filters were filled up with diesel prior to install on the pump. I did about a one second power on to ensure connectivity. Yeah, much quieter than I remember.
- Add zip ties to secure power and fuel lines as things should be.
- The power connector on the pump was damaged at some point over the years of misshandling so the lock tab is AWOL. I'll have to affect the necessary repairs for that too.
- Put away toys, er, tools.
Finally, the old LP Power connector will get weather sealed for preservation and 'just in case.

 

[ak diesel driver]

I used to original LP harness to trigger the relay so I had nothing to cap. Nice job though.

 

[Paveltolz]

Hope everyone remembered to celebrate their moms yesterday.
This morning I did the tidy up stuff, bled the lines of air at the IP and keyed it on.
No leaks at any of the connections, or from the pump itself, pressure at 12psi, could hear the fuel returning in the fuel filler pipe.
Start up was normal. Engine ran without hickups so the all the air was out of the system.
Fuel pressure at idle is 10psi so the pump is adjusted correctly.
Going for a drive....

 

[Paveltolz]

Test drive complete. Pressure at idle came up and bounces around between 12-14 psi. Never drops below 12 in normal traffic.
10psi min. under HARD acceleration.
Depending on who one asks. Stanadyne likes no more than 10 psi so I'll back it off.
Truck runs happier though. Doesn't matter if just bouncing around in traffic or clearing out a lot of space between everyone else.

 

[jrsavoie]

Location Location...As I was saying, Initially, I’d planned to place this set up in the same location as the stock lift pump. In fact, that's the way I remembered it but, with the torsion bars blocking clearances for the filters, I obviously had to adjust things ‘a little more to the left’ and placed it behind the torsion bar frame cross member. The thought of adapting the PureFlow ½” lines to the OEM fuel lines from the tank was never an option at the stock LP location anyway and, had it been, it was no longer an option (for 2024, they ask you to cut the steel line making a retro-fit to OEM lift pump a new project). But, I made things work and it worked fine until it didn't. Fast forward to 2024.

So, I'm under the truck, tryin' to remember just where I'd actually had this thing located in 2017-ish. I had to go back to old pictures and looking for the two holes i'd drilled for the mounting plate to fit. Once that was done I tried fitting the pump and couldn't understand how I'd gotten it in there in the first place. The top of the pump was pushed up against the cab floor and the bolt holes in the frame and the bracket were off just enough. This pump is heavy w/o the full filters and the fun meter is pegged at zero.

I wrangled it in but, the wires on the new pump were pinched against cab floor.
Memory cells kicking in and I remembered the pump being very noticeable both audibly as well as it could be felt in the cab. Ah ha. I wonder if the old one failed because I failed to notice the wires were too close/in contact to the cab floor. Live and learn.

I pulled out the 'scrap' pieced of mounting plate (almost tossed that thing a month ago) and did some comparisons.
View attachment 87624
By using the one on the left (which also fit perfectly inside the 7" frame rail) and running just one Grade 10.9 through the lower hole in the plate, I could gain the clearance between pump and cab by 1/4 inch. Saves not having to drill two more M-10 sized holes or oval out the existing ones. An added bonus was my fuel line to the LP would now reach since I was removing the Diesel Sites filter (vs. the FFM) at the front of the engine. Yeah, I did have to trim back the feed line from the tank but, it was a rubber line vs. the braided steel bling looking crap I'm into running forward.

Lines.
For the tank to pump feed line, I trimmed off the now excess, inserted a -6AN 45* twist loc fitting and secured with a hose clamp and job done.
View attachment 87627
For the return to tank line, I utilized thisRussell Performance 180* -6AN twist loc w/ a larger arc.
View attachment 87628
I used a new rubber diesel rated hose and ran it back to the old 1/2" hose still attached to the fuel filler neck. I utilized a two-sided brass adaptor to make the conversion to 3/8". It's the top fitting in this mock up picture. The others were considered and discarded. Ignore the brass fitting on the right, this isn't the hose I used.
View attachment 87625

I can't believe someone would throw out a usable pie e of metal LoL

I might be a hoarder

 

[Big T]

I fell asleep on the train reading this and nearly missed my stop in Fullerton.

 

[Big T]

My reward, this morning’s train ride was delayed some 40 minutes because some idiots decided to steal the copper out of the track switches, which meant they had to pull the switch manually.

 

[Will L.]

My reward, this morning’s train ride was delayed some 40 minutes because some idiots decided to steal the copper out of the track switches, which meant they had to pull the switch manually.View attachment 87679

Although maybe YOU didn’t choose this group,
Still falls under:
You get what you vote for

 

[Big T]

Although maybe YOU didn’t choose this group,
Still falls under:
You get what you vote for

After they legalized ballot harvesting in CA, I realized my vote no longer counted. In the 2018 mid-terms, they flipped my traditionally GOP voting district to Dem and elected a one-term wealthy lottery winner by backing up trucks filled with ballots late in the evening. While that has since been flipped back to GOP, I knew my vote no longer counted in CA and I am now registered to vote in Montana.

 

[Paveltolz]

Talk about derailing a thread…

 

[Big T]

Talk about derailing a thread…

That’s ^^^ for five word thread.

 

[Paveltolz]

Back to the train of thought.
I noticed that there might be a bit more smoke vs. occasional quick stab puffs.
Thinking it could be:
A. Lift pump pressure but, injectors deliver what the deliver and there’s been no lack of power the the truck feels happier.
B. SoB air filter is restricting air.
C. Happy Foot needs recalibration.

More likely C. I’ll drive it a while and see if things calm down in the “foot to fun” department.

Fuel mileage will tell too.

 

[Big T]

Back to the train of thought.
I noticed that there might be a bit more smoke vs. occasional quick stab puffs.
Thinking it could be:
A. Lift pump pressure but, injectors deliver what the deliver and there’s been no lack of power the the truck feels happier.
B. SoB air filter is restricting air.
C. Happy Foot needs recalibration.

More likely C. I’ll drive it a while and see if things calm down in the “foot to fun” department.

Fuel mileage will tell too.

I’ve had air filter issues, as you know.

 

[Paveltolz]

For Reference Sake as there was some discussion on the ‘What did you do….’ thread.

Raptor and AirDog pumps are manufactured by PureFlow Technologies.

"Since 1990...PureFlow ® Technologies, Jefferson City, MO, and PureFlow® AirDog®, Shelbyville Indiana, have developed Fuel Preporator ® and AirDog ® models for virtually every diesel engine application...."

The Raptors have what appears to be a vertically mounted pump, do NOT have a filter and does not return any excess fuel to the tank directly so, you’re on your own for either a pre-filter or one downstream. Excess fuel is returned to the tank via the IP and Injector return lines.


FWIW, I removed my FFM years ago when I first installed the AirDog. When I put a stock LP back in I installed 2 Micron filter set up similar to what I had on the Walbro before all that.

The AirDog systems have a water separator and fuel filter incorporated in the set up and utilize a horizontal mounted “Gerotor” pump. Excess fuel, void of water and air, is returned from the pump to the tank.


The latest 5G models have a diaphragm regulator mounted on the pump motor vs. the filter body and an integral 1/8" NPT port for fitting a fuel pressure gauge. Upgraded harness (12 vs. 14 gauge) and connector too.


Member Cumminalong did a side by side back in 2009 between FASS and AirDog. You can read it here. But, the cliff note version was that they are both good pumps (then) and the differences weren't worth falling on a sword for.

Over the last 17 years, in this order, I've run:
2007 OEM LP on the truck when purchased. Upgraded.
2011 Walbro FRB-5. Upgraded.
2012 AirDog II DF-165. Failed Motor, replaced. AirDog sorta honored the warranty with a low cost replacement pump.
2017 (?) "Heath" OEM 1994 LP. Locked up / failed less than in one year and replaced. Later, tapped with hammer and it ran again. Sitting on a shelf somewhere in the shed.
2018 O'Reilly OEM LP. Upgraded.
2024 AirDog II DF-165

 

[Will L.]

The spin on filter & water separators from either of those two are far superior to the factory FFM. I really prefer the water separator from Fass because it is a zero flow once full of water. People with a pressure gauge would notice the fuel supply drop both in feeling and the gauge before the engine shuts off.

@Paveltolz
At 2 microns the reports are gelling begins to be an issue. Have you had any issues? The recommended thing is a fuel heater in the system pre filters or in the filter/pump assembly itself rather than emulsifiers.

 

[jrsavoie]

The spin on filter & water separators from either of those two are far superior to the factory FFM. I really prefer the water separator from Fass because it is a zero flow once full of water. People with a pressure gauge would notice the fuel supply drop both in feeling and the gauge before the engine shuts off.

@Paveltolz
At 2 microns the reports are gelling begins to be an issue. Have you had any issues? The recommended thing is a fuel heater in the system pre filters or in the filter/pump assembly itself rather than emulsifiers.

I used to run a 2 micron filter in the ffm. Never had a gelling issue.

I was running B11 or B9. I suddenly can't remember.

I ran White Power Service or Schafer's additive and double dosed

 

[Paveltolz]

@Paveltolz
At 2 microns the reports are gelling begins to be an issue. Have you had any issues? The recommended thing is a fuel heater in the system pre filters or in the filter/pump assembly itself rather than emulsifiers.

No issues with gelling/reduced pressure during the years I ran it previously. I drained the water filter approximately every 6 months. In the winter, w/o a heater, I never had any issues.
I saw a video from PureFlow about proposals for a fuel heater in development. That was 8 years ago and still nothing. They did say they have customers in colder climes that request part numbers for a 10 micron alternative. Apparently, they don't mind giving out the compatible filter part numbers for other manufacturers.