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So, basically what the title says. I'm interested in mixing and matching bits from a later gen sending unit, in my 2nd gen's.  I'm not running any power mods, and lately my fass drp has had intermittent defueling at highway speed. Continued after changing fuel filters.

Truck has 370k+ miles on it, big stock, the most recent 150k have been mostly highway. 

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I have run the in tank pump like the 3rd gens. It was no better than the block mounted pump. The VP trucks just are not the same as the 3rd and 4th gens and require different things. The in tank might be good for a CP3 but not so for the VP. I dont know anything about the 4th gens. Others here would know much more than me on the subject.

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15 hours ago, Old Blue - 1998.5 said:

Fuel Boss or other mechanical lift pump. Only way to go.

That seems a bit overkill for a bone stock truck.

 

As to a vp44 and cp3 having differing specs, so far, what specs I can find for a 2011 lift pump is similar to a Fass drp 2.0 that is currently onboard.

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2 hours ago, jimmystikx said:

That seems a bit overkill for a bone stock truck.

 

 

No not really. I have a DTT Assassin mechanical pump, bone stock truck except for a quad, no other way to go, FP goes UP with RPM not down, pushes fuel through 2 micron Cat filters easily and removes an electrical item from an already electrically challenged truck

before this I had a Fass DRP,  truck had a intermittent cough/splutter, sock was clean, don't look at FP now, fuel temps towing 5th wheel no higher than 120f on 1/2 tank and 110f on full tank

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fuel boss or mechanical pump vote here.

5 hours ago, jimmystikx said:

That seems a bit overkill for a bone stock truck.

 

As to a vp44 and cp3 having differing specs, so far, what specs I can find for a 2011 lift pump is similar to a Fass drp 2.0 that is currently onboard.

bone stock trucks will get the vp44 killed by a weak lift pump. its basically a known fact that you MUST upgrade lift pumps on these trucks, stock or not. mine has rv275's, and a tuner (only for monitoring) and is otherwise "stock". im not in for power, i am in for reliability and longevity. Having a weak lift pump will cost you $1500 in a new vp eventually.

 

another advantage of a mechanical lift pump, you remove the electrical load on the ECM which has also been proven to be killed by having the oem lift pump. (my ECM lift pump circuit is dead) so there are many advantages to mechanical.

Edited by CUMMINSDIESELPWR
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I have the AD165 in mine. It runs off of a relay triggerred by oe pump connection. That gets power off of the ECM also. I did'nt know about the mechanical pumps way back when. A lot of folks here run them with very good succes. If mine were to fail again I would probably go with one. 

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Once you consider how expensive the replacement electrical pumps are, how it seems like they are prone to trouble after three or four years, how a long slow decline in fuel pressure can eventually take out your expensive VP44, and the increased electrical load on the vehicle's ECM (and system as a whole) and the fact that many of the electrical pump motors are not well-shielded against electrical noise and AC....Well.

The picture was clear to me.

Mechanical pumps are much more reliable, predictable, not prone to as many side issues related to the electrical system as a whole. I love the fact that the rig starts instantaneously and builds good fuel pressure and keeps it, even increasing slighty from idle to max rpm and load.

 

Care and proper feeding of your VP44 is the answer to a long and trouble-free experience....well...at least as that component in your fuel system is concerned.

 

No regrets; expensive, but worth it at the pay-off.

 

Cheers....

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14 hours ago, Old Blue - 1998.5 said:

Once you consider how expensive the replacement electrical pumps are, how it seems like they are prone to trouble after three or four years, how a long slow decline in fuel pressure can eventually take out your expensive VP44, and the increased electrical load on the vehicle's ECM (and system as a whole) and the fact that many of the electrical pump motors are not well-shielded against electrical noise and AC....Well.

The picture was clear to me.

Mechanical pumps are much more reliable, predictable, not prone to as many side issues related to the electrical system as a whole. I love the fact that the rig starts instantaneously and builds good fuel pressure and keeps it, even increasing slighty from idle to max rpm and load.

 

Care and proper feeding of your VP44 is the answer to a long and trouble-free experience....well...at least as that component in your fuel system is concerned.

 

No regrets; expensive, but worth it at the pay-off.

 

Cheers....

 

Any suggestions on the sending unit then, or are you using the stock intank pump to prime the system, and then drawing through it?

 

5 hours ago, Mopar1973Man said:

Rumor is that the 5th gen pumps are actually pretty good. Just need to modify the unit to fit into the fuel tank.

This is the tech I'm interested in, especially since a lot of the factory type pumps will have good emi suppression and a relatively decent lifespan.

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3 minutes ago, jimmystikx said:

Any suggestions on the sending unit then, or are you using the stock intank pump to prime the system, and then drawing through it?

On the assassin you fit a drawstraw to the fuel basket, this is the "new" supply,  the tee at the rear of the head goes to the smaller connection on the fuel basket and the fuel pressure regulator which is in the kit goes to what was the old fuel supply, most of what is in the fuel basket is chopped out, looks to me like the Fuel Boss uses a 1 1/2" steel tube in the filler hose with a 1/2" stub welded into it for the returns

Mechanical pumps don't  need an electrical pump to prime the system, if the system is bone dry then you drop the pump down and prime with a drill, takes about 5 minutes, if there is fuel to start the truck it bleeds itself, I've had most of my lines off today fixing the steel return from the Tee which had cracked, didn't bleed it once

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@jimmystikx

 

Mine is a February 98.5, so it not have any of that stuff. It had the original Carter on the side of the engine drawing through the 1/4" hose. My VP44 died when the computer on the pump quit communicating with the ECM. So I sprung for the high dollar Blue Chip unit (with the extended warranty on the processor). and after reading, research, and thinking, decided the Fuel Boss was the way to go. Coupled with the big line kit and the good fittings that flow more and a fuel pressure gauge....I am much more confident that I will get a good lifespan out of the VP44.  For priming I have fitted an Airtex-Wells replacement tee-ed in at the original location. I can use it to prime at start to 5-6 psi, then after the engine fires the mechanical pump builds pressure quickly to 15-16 PSI.  Most of the time, though, it will start immediately as soon as the starter is engaged. After sitting for months through the winter, it fired and ran in like two seconds this spring. (after I re-installed and charged the batteries).

 

One advantage of this system is that the electric lift pump is still in place. If for some reason I need to prime, or of the mechanical should fail, I can throw a switch and turn on the electric pump for a back-up, or to prime for a longer time.

 

Running down the road I usually see 17-18 psi at speed. On a high rev downshift it'll bump up to 19-20 psi. Pressure and flow increase with RPM.

 

And that is a good thing to have....

 

Good Luck with Yours, whatever you choose to do.

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I haven’t heard anything different about the specs on a 19+ pump vs the 03-18 in tank pumps. 
 

They are reliable, cheap, and provide plenty of fuel for a common rail engine,  but as @dripleymentioned they don’t have the same requirements as a VP44 truck. A CP3 needs flow, not pressure. Bosch specs are -5 to +15 psi. A CP3 truck runs at about 10 idle, 7-8 cruise, and 4-7 under load. Too low for a VP based on what I’ve been told. 

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9 minutes ago, AH64ID said:

I haven’t heard anything different about the specs on a 19+ pump vs the 03-18 in tank pumps. 
 

They are reliable, cheap, and provide plenty of fuel for a common rail engine,  but as @dripleymentioned they don’t have the same requirements as a VP44 truck. A CP3 needs flow, not pressure. Bosch specs are -5 to +15 psi. A CP3 truck runs at about 10 idle, 7-8 cruise, and 4-7 under load. Too low for a VP based on what I’ve been told. 

To be honest I think a vp needs flow not pressure, problem is flow needs to be the same at idle and wot

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On 8/9/2020 at 12:06 PM, wil440 said:

To be honest I think a vp needs flow not pressure, problem is flow needs to be the same at idle and wot

flow yes to keep cool fuel flowing through,  pressure needs to stay above 15 to ensure flow happens, on a stock truck you wont see much pressure drop from fuel going to injectors but on built engines you can see the pressure drop from hammering down and you still need to be above the 15psi to keep the flow going.

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37 minutes ago, CUMMINSDIESELPWR said:

flow yes to keep cool fuel flowing through,  pressure needs to stay above 15 to ensure flow happens, on a stock truck you wont see much pressure drop from fuel going to injectors but on built engines you can see the pressure drop from hammering down and you still need to be above the 15psi to keep the flow going.

I've done a lot of checking and testing on this on my truck last week and my truck has a bleed orifice in the overflow valve at the vp and it flows a huge amount of fuel back to tank at 5 psi at idle, I have an assassin mechanical pump and use cat 2 micron filters, I've been running my assassin on high gearing to get higher idle pressures through the 2 micron filters but last week I changed the gearing back to low to test and have 5 psi at idle and 25 psi at 2k ish. I have tested the return from the Tee by replacing the steel line with 3/8th rubber and having the tank end in the filler neck to check return and it's a lot

I have a 5 micron fleetguard filter on it's way to see if that gets me higher than 5 psi on the low gearing... more to test than anything else.

I replaced the overflow valve with the correct part number from  Cummins 467-445-003, same as the old one and the same 5psi at idle, I will add my pressure increases really fast straight off of idle

So on my truck at least FP doesn't need to be 15 to get return flow, this 5psi I'm seeing must be attributed to my 2 micron fuel filters but I will keep testing until I'm sure, I don't know why because my fuel temps are 110f to 120f and it takes  ages to get to 120f and never on a full tank and  I can just use the higher gearing pulleys and be fine.... lets just say i'm curious

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Posted (edited)

Not to put another thought in there, but Cat doesn’t have a 2um filter. 2um hasn’t been a rating since 2004. Their commonly called 2um is 4um. 
 

The FF5814 is the most modern and best filter in that sizing. It’s 3um and has the NanoNet media. 
 

If the filter is clean is shouldn’t have a noticeable impact on pressure. I pushed thru 3 filters with my stock in-tank and saw the same pressure as guys with 1 filter. 
 

What Fleetguard did you order? 

Edited by AH64ID
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5 hours ago, AH64ID said:

Not to put another thought in there, but Cat doesn’t have a 2um filter. 2um hasn’t been a rating since 2004. Their commonly called 2um is 4um. 
 

The FF5814 is the most modern and best filter in that sizing. It’s 3um and has the NanoNet media. 
 

If the filter is clean is shouldn’t have a noticeable impact on pressure. I pushed thru 3 filters with my stock in-tank and saw the same pressure as guys with 1 filter. 
 

What Fleetguard did you order? 

Interesting... my Cat  SIS web Lists it as a high efficiency 2 micron filter 1R-0750 i'll check it when I get to work as sis is on my work laptop, easy to test as I can put pressure gauge into filter inlet  and measure the difference

FF 5320 is what's coming

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12 hours ago, wil440 said:

I've done a lot of checking and testing on this on my truck last week and my truck has a bleed orifice in the overflow valve at the vp and it flows a huge amount of fuel back to tank at 5 psi at idle, I have an assassin mechanical pump and use cat 2 micron filters, I've been running my assassin on high gearing to get higher idle pressures through the 2 micron filters but last week I changed the gearing back to low to test and have 5 psi at idle and 25 psi at 2k ish. I have tested the return from the Tee by replacing the steel line with 3/8th rubber and having the tank end in the filler neck to check return and it's a lot

I have a 5 micron fleetguard filter on it's way to see if that gets me higher than 5 psi on the low gearing... more to test than anything else.

I replaced the overflow valve with the correct part number from  Cummins 467-445-003, same as the old one and the same 5psi at idle, I will add my pressure increases really fast straight off of idle

So on my truck at least FP doesn't need to be 15 to get return flow, this 5psi I'm seeing must be attributed to my 2 micron fuel filters but I will keep testing until I'm sure, I don't know why because my fuel temps are 110f to 120f and it takes  ages to get to 120f and never on a full tank and  I can just use the higher gearing pulleys and be fine.... lets just say i'm curious

in the overflow banjo bolt, there is a tiny bypass hole that will flow fuel out of before the pressure builds up enough to crack the sprung ballvalve inside the banjo bolt at 14psi, then flow is even greater. so yes technically you will get flow from the overflow banjo bolt but not anywhere near what the flow iwll be when the ballvalve is open (unless its broken and stuck open)

 

 

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I'm getting good flow at 5 psi at idle with a brand new cummins overflow valve... same flow and psi as the old one I just removed. I need to check further me thinks.. 

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2 hours ago, wil440 said:

I'm getting good flow at 5 psi at idle with a brand new cummins overflow valve... same flow and psi as the old one I just removed. I need to check further me thinks.. 

 

I don't think that there is any mystery here.  To my knowledge the lift pump feeds directly into the inlet of the fixed displacement vane pump inside the VP44.  The discharge flow of the vane pump is regulated at over 100 psi.  The 14 psi overflow valve is one of many components is in the path of the internal vane pump discharge, consequently there is always return flow through the 14 psi overflow valve - even when there is only 5 psi lift pump pressure.

 

- John

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On 8/11/2020 at 8:01 AM, wil440 said:

I'm getting good flow at 5 psi at idle with a brand new cummins overflow valve... same flow and psi as the old one I just removed. I need to check further me thinks.. 

what is good flow? for me good flow would be more fuel through the vp back to tank than what is used by the engine. some would say a steady small stream is good flow...   not enough fuel through the vp back to the tank is not sufficient to cool the vp.

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Posted (edited)

Typically it was only the 12V with overflow problems because the bolt was soft steel and the ball would beat the seat out. 24V overflow valves typically don't fail. 

 

I know you have the belt driven lift pump.

 

Heck I just did a 16 hour day, ran my truck over 414 miles doing a injection pump job in Anatone, WA. The entire day was cool out and truck was kept running most of the day with driving. I had temps ranging from about 65*F to a high of 80*F in Lewiston. Climbing 3 different grades and a few good twisting roads. I even had to go back to Lewiston for a special tool to pull injectors and back to Anatone, WA in the back country. Fuel temp never over 120*F the entire day, 414 miles, 5am to 9pm... Long day...

 

Screenshot from 2020-08-13 12-54-28.png

Edited by Mopar1973Man
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