Choosing The Right Fuel Lift Pump For My Needs

[keithb7]

Hi folks. I am interested in settling on the right fuel transfer pump for my 1998.5 24V 2500. My engine is stock. I have no plans to increase horsepower or torque. I have 157,200 miles. 
I bought the truck last August. Right before I bought it,  the VP44 had failed and been replaced in June. However the lift pump was not replaced.  I decided to dig in a learn a bit about this known problem. I purchased a fuel pressure test gauge and checked the stock Carter pump. Readings were ok for the stock system, but a little down. I decided to change it out ASAP with another stock Carter pump at that time. I wanted to experiment and track some results. With the new Carter in I was getting 10 psi at idle. Dropping down about 6.5 to 7 psi pulling a steel hill. I proceeded to install a digital ISSPRO fuel pressure gauge and drove in that state it over the past winter.  

 

Over winter, I continued on to read about various high performance fuel lift pumps. I bumped into the Airtex or Herko fuel lift pump. Priced at about $70 so I decided to try the Herko. I put it in about a week ago. Fuel pressure at idle is 16-17 psi. Pulling hills drops to about 9-10 psi. A considerable improvement over the stock Carter. Hi-way speeds on flat ground the Herko makes about 14 psi. My understanding is the check valve inside the VP44 opens at 14 psi allow for proper full cooling of the pump electronic circuit board. Is this correct? It seems odd to me that the Bosch needs to see 14 psi to cool, yet Dodge engineers chose a max-10 psi at idle, fuel pump. 

 

I own a 23 ft travel trailer I plan to tow. If the VP44 does indeed need 14 psi for proper cooling, I suppose I should be looking at a pump that can maintain minimum 14 psi at all times. Am I on the right track here? Do I really need to be looking at these expensive AirDog or FASS pumps at $600 to $800? Seems pretty pricey for a stock HP truck. I understand that saving the VP44 is the idea here, as they are big bucks. Looking at the Gino's catalog here as I type this, they offer a mid-level upgrade. The FASS High Performance Adjustable Fuel Pump at $464. I assume if I go this route I'll also need to upgrade the fuel suction lines.

 

It's been interesting learning about the various pump options. I have already spent $200 screwing around with pumps and learning. I do my own work and do enjoy it. Thoughts and tips settling on the right right lift pump for me are appreciated. Thanks. Keith

 

Edited March 24, 2019 by keithb7

[JAG1]

Nice truck Keith. I like what you did to the front bumper and grill. very nice.

 

I have Raptor 150's on both my second gen trucks. They are okay, but the new style regulators were and still are a little erratic when new. I know regulators have a tougher time doing their job if fuel lines (suction and pressure side) aren't big enough and restricts the regulators ability to maintain the desired range.

 

I know from experience the factory lift pump, even when relocated on the frame and you change the fuel lines to 1/2 inch all the way is really not enough to do the job. You gain only about 1 p.s.i. when you finally change the draw straw to 1/2' in the tank', but you need to get in there anyway to remove the screens and allow more flow into the fuel basket.

 

There is a lot more than just what I've mentioned..... some very important items about power source for the lift pump being on a relay and using 2 stroke oil to bring lubricity levels up to what the injection pump needs. I will let others chime in on that.

 

 

Edited March 24, 2019 by JAG1

[IBMobile]

First off, nice looking clean truck.

 

I went through 3 Carter left pumps and read all the problems people were having with their electric lift pumps so I installed a mechanical Fuel Boss lift pump with the supplied 3/8 fuel lines and stock fuel tank pickup without a draw straw.  I plumbed in a cheap Airtex pump that I've used to purge air from the system but is unused the rest of the time.

 

The fuel pressure is 18-19 PSI going down the road with Rv275 injectors and an Edge EZ  towing an 8K fifth wheel with a boat behind that.  

[Mopar1973Man]

Biggest factor your up north in the cold country. I would suggest an AirDog and do some creative mounting. As for the FASS it's very very large and tends to hang in the damage path of the front tires. The pump needs to be strong enough to maintain 14 to 20 PSI at all times including WOT. With Canada cold you need a fuel system that can be tuck away from snow and ice and out of the blowing wind. 

 

This is a good layout. Protected by the transfer case and the skid plate. I've been to -40*C (-40*F) never gelled once. Since this picture I've moved my fuel lines inside the frame. Better protection from blowing cold. 

 

This is a bad layout and more prone to gelling up.

 

 

[dripley]

4 hours ago, keithb7 said:

It seems odd to me that the Bosch needs to see 14 psi to cool, yet Dodge engineers chose a max-10 psi at idle, fuel pump. 

 

The 14 psi is where the return valve is fully open. It has a bypass that always lets some by all the time. I cant remeber at what pressure the valve starts to open. Maintaining a 14 psi minimum just assures the VP is gettoing all the cooling available from the fuel. IIRC Bosch's pressure requirements were in the 5 to 10 psi range. Some one with better knowledge will correct me if wrong.

 This was all based on how the rolled off the showroom floor and before folks started strapping performance enhancements and the diesel we use has modified. This also brought on the use of fuel additives such as 2 stroke oil to help the lubricity of the fuel. A stock truck can get away with lesser add onsbut I am no expert on that.

[Mopar1973Man]

Just now, dripley said:

IIRC Bosch's pressure requirements were in the 5 to 10 psi range.

 

[Bullet]

If you never ever want to deal with a lift pump issue ever again during your ownership of the truck...the only way to guarantee that is to go belt driven mechanical.  Cost is about $500-600 and there are about 4 different brands to choose from.  It's also the only style of lift pump that will supply more pressure as throttle increases rather than less.  Mine supplies a constant 18psi at idle and 20psi at higher throttle levels and has never varied from that.  I carry an extra belt with me that can be changed anywhere anytime in 5 minutes and belts are recommended for 50k miles and I was given my extra belt as condition of the sale. 

 

There are some pretty good electric pumps out there but they all will eventually fail.  They have great warranties which cost you nothing to replace them but you still will eventually have to replace them and risk a VP44 or be down until you get a new one.  Their warranty will not cover a new VP if it dies because of a failed warrantied electric pump.

 

There's has been plenty of bad press about all brands of electric pumps but none to be found on mechanicals...that's what made my decision for me. 

[BBHD]

2 hours ago, Mopar1973Man said:

As for the FASS it's very very large and tends to hang in the damage path of the front tires. 

I have had my FASS titanium 150 on for many years now and never had an issue with it being tucked up under the front of the bed. I spend my winters above 9000' in Colorado and have never had it gell. I travel between New Mexico and Colorado all year long with several trips into Wyoming, Kansas, Nebraska and Texas. A mix between interstate, 2-lane, gravel and 1000's of miles off road. Knock on wood I have yet to ever have anything damage my set-up. Just my . If something does happen and it gets damaged or dies I'll be going the mechanical route as many here and elsewhere have had great success with them. 

[keithb7]

Thanks folk for the great feedback an insight. I like the ideal of a mechanical pump I will look into it.

[cumminsdog]

Move forward with a mechanical pump & don't look back !

[Marcus2000monster]

I have a Fass Titanium 150 but I would follow along with the mechanical pump. Seems like a fool proof design. 

[01cummins4ever]

https://www.glacierdieselpower.com/c-92-fuel-system-related-fuel-boss-pumps-accys-fuel-boss-mechanical-lift-pump-systems.html

Go with the fuel boss and you will only cry once 

You can plumb these in different configurations, add extra filtration,  keep you existing pump for primming, etc.. 

 

You can get a hold of Richard at GDP, tell him what you want and he can set you up

[JAG1]

I know that it is very important to be able to add extra filtration. I'm talking about the importance of a pre filter that is water separating so the lift pump does not get a chance to emulsify the water into the fuel. This allows the factory small filter to do it's job without ever getting overwhelmed with water or larger sediments.

[Rotax3006]

I'm probably the odd man out here but I have a stock pump (carter) on my truck.  My fuel pressure sets at 13-14 idle in the warmer months and 12-13 in the cold.  I will drop to about 9-10 at WOT.  My  last VP went 252000 miles without adding and 2T although I usually ran cenex road master fuel (supposed to have additional lube).  I would go to a mechanical pump if I was going to change it out.  I guess for me the most important thing is to keep an eye on the pressure and make sure it meets those stock parameters.  I think the VP got a bad rap early on when everybody was adding power with tuners and a marginal at best stock pump.

[Mopar1973Man]

Interesting... I've got to ask what is the stated HFRR score for that fuel.

 

[Tractorman]

On ‎3‎/‎24‎/‎2019 at 7:22 AM, keithb7 said:

My understanding is the check valve inside the VP44 opens at 14 psi allow for proper full cooling of the pump electronic circuit board. Is this correct?

 

Yes, this is correct.

 

On ‎3‎/‎24‎/‎2019 at 7:22 AM, keithb7 said:

It seems odd to me that the Bosch needs to see 14 psi to cool, yet Dodge engineers chose a max-10 psi at idle, fuel pump.

 

Actually, it is not odd.  There is a fixed displacement vane pump inside the VP44 injection pump.  This vane pump rotates at the same rpm as the VP44 and provides fuel flow for cooling of the VP44 as well as some other duties.  The internal vane pump provides much more fuel than is being consumed by the injectors.  Consequently, the fuel pressure rises internally and the excess fuel is forced over a relief valve that is set at over 100 psi (not sure of the exact pressure) and the fuel is returned to the suction side of the internal vane pump.  The inlet of the 14 psi relief valve is in common with the outlet of the internal vane pump (operating at more than 100 psi), so there is always fuel flowing over the 14 psi relief valve regardless of the lift pump pressure. 

 

The primary function of the lift pump is to supply more fuel to the VP44 than the VP44 can consume for cooling and powering the engine under all operating conditions.  Since lift pump is flowing more fuel to the internal vane pump than the internal vane pump can use, this flow restriction is what determines the lift pump pressure reading that you see on the lift pump pressure gauge.

 

My VP44 and lift pump were replaced under warranty at 87,000 miles.  An in-tank lift pump was installed (a factory decision).  The original lift pump was still good - 12psi at idle and 7 psi at wide open throttle at 2500 rpm in 5th gear. The in-tank lift pump tested at 6 psi at idle and 3 psi at wide open throttle in 5th gear.  I was not concerned.  I ran the configuration this way until 250,000 miles on the odometer and then I removed the in-tank pump and installed a frame mounted FASS 95 g/hr pump with a suction screen.  I did this modification to make a roadside repair possible.  At this time I also added a low fuel pressure warning switch with an indicator light on the dash. 

 

I am now at 309,000 miles.  The replaced VP44 has logged 222,000 miles with lift pump pressures that never see anywhere near 14 psi and most of the time considerably less.  Also, I have been using the Smarty S03 programmer for the last 50,000 miles and I just replaced the OEM injectors with RV275 injectors.  All of the fuel lines are stock and with the exception of a 150 micron suction screen for the lift pump, the fuel filtration system is stock.

 

Back in 2001, Mopar-Muscle posted the results of a test using a flow meter installed on the return line after the collection point of all returning fuel flow.  Below is part of a thread out of the Cummins Forum showing the results of two tests.

 

- John

 

Test # 1

1. well some of you guys ain't gonna like this , especially those led to believe (and those that believe it) ... the bigger is a MUST theory .
   
   spent a couple minutes running some tests with a DIGITAL/mechnical flow meter and a MECHNICAL fuel pressure gauge , items under test ... 2000 RAM , DD2's , DD TTPM on level 2 (??) and a HOT PE , ( all levels tested the same at WOT)factory pickup , factory lift pump , factory fuel filter housing unmodified , all banjo bolts intact and unmodified except the banjo to the input of the lift pump is replaced with a 90* swept areoquip type -6AN hose end , the bolt at the lift pump had the schrader cut off and drilled and tapped to a 1/8 npt ( for the gauge) and the banjo fittings between the lift pump and the fitler housing have been drilled to 9/32nd . again all banjo bolts are not drilled out as i have on my ram ( test conducted on the DTT RAM ) .
   
   we installed ( LaserBob is helping me and getting #2 fuel poured on his head ) a Sonnex digital flow meter ( inside ID is 5/16") in the return line back to the tank , cut in right at the trans crossmember . gph numbers are fuel returned to the tank .
   
   
   DD2 , DD TTPM (True Torque Power Module)
   FP volume
   idle 11 psi 18gph
   
   cruise 8 psi 24gph
   
   WOT 2 psi 30gph
   
   
   DD2 , TTPM , HOT PE ANY LEVEL
   FP volume
   idle 11 psi 18gph
   
   cruise 8psi 24gph
   
   WOT 0 psi 30gph
   
   
   yes you read that correctly , fuel pressure went to 0 and the fuel volume back to the tank did not change from WOT with 2 psi . the truck did NOT stumble , buck , spit , fart , fall on it's face , nothing , ran like all heck at 0 psi , i will note , my truck ran the same at 0 psi with the DD3's , EZ and a HOT PE .
   
   tomorrow we will install -8 lines and an HP carter pump , take flow readings in exact same spot and see what the results are .

 

Mopar-muscle, Apr 24, 2001 Report

 

Test # 2

 

1. well , here we go again , todays test was interesting to say the least , and we believe we have it figured out .
   
   added the carter HP 15psi 110gph pump on the frame rail next to the tank , -8 bulkhead in the bottom center of the tank , -8 line to the pump , -6 line from this pump to the inlet of an unmodified factory 2000 fuel filter housing , the rest of the system is as delievered from the factory except for a banjo bolt that had the schrader cut off and tapped to 1/8 npt for the gauge , the digital flow meter in the exact same location reading flow back to tank after the tee on the engine .
   
   with DD2 , DDTM (True Torque Power Module)
   
   psi volume
   idle 11. 5psi 18gph
   
   cruise 9psi 24gph
   
   WOT 6 psi 30gph
   
   
   with the HOT PE on any level
   
   idle 11. 5psi 18gph
   
   cruise 9psi 24gph
   
   WOT 4psi 30gph
   
   with the addition of the new pump and larger gravity fed pickup point the flow to the tank did not change , though pressure was up , the carter having an internal bypass is living with the backpressure on its output .
   
   the concenus is the VP44 is the restriction . the return line from the pump is only returning the excess fuel from the VP44's own internal pump , the more you feed it the higher the backpressure on the line to the pump .
   
   the guys with the large pumps , bigger lines and regulator mounted as close to the VP44 as possible have a large amount of the excess flow returned directly to the tank , this is not a bad thing ,( except that at a low fuel level it is possible to foam the fuel in the tank with the large amount of fuel dumping back into it from 2 sources ) but is really overkill as the vp44 uses a set amount of fuel and this is proved by the higher pressure seen with no increase in flow back to the tank .
   
   again , the higher the pressure , the lower the flow , BillW explained it perfectly on the prime loc bashing thread and no one ( including myself) understood it or tryed to test it to see if it was true .
   
   someone asked if there was a pump that was between 60 and 100 gph , again carter to the rescue , there street pump , 15 psi , about 70 gph , this pump mounted as close to the tank as possible is the best scenerio .
   
   the factory designed the system to have the least amount of restriction with the most flow given the flow characteristics of the VP44 .
   
   i have not seen the info on HVAC's 34 hp increase with fuel system mod , i will be talking to him to find out the poop on that .
   
   we also felt what happens when you have no flow , we had a low fuel level in the tank and under the bulkhead at the botom of the tank , the engine cutout , if the 0psi had no flow , we would have experienced this same bucking .
   
   next we will move the factory lift pump back in place of the carter hp pump
   
   [This message has been edited by Mopar-muscle (edited 04-26-2001). ]

 

Mopar-muscle, Apr 25, 2001 Report

 

 

[AH64ID]

Personally I like the FASS 95 GPH pumps, as they don't outflow their filters like the AD or 150 GPH pumps. 95 GPH is plenty of fuel. 

 

FASS also has standard sized filter threads, and easily added fuel heaters. 

[Rotax3006]

20 hours ago, Mopar1973Man said:

Interesting... I've got to ask what is the stated HFRR score for that fuel.

 

So according to Cenex its 430. They say 10-15% better than traditional fuel.

[JAG1]

22 hours ago, Rotax3006 said:

  I think the VP got a bad rap early on when everybody was adding power with tuners and a marginal at best stock pump.

Is it true that the early VP's  also did not have a steel sleeve for the timing piston? Bosch may have made other improvements as well, if you've heard anything.......

[Mopar1973Man]

Brass timing sleeve to steel timing sleeve.

 

Rubber diaphragm to steel plate.