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Since reading the thread about the gentleman in Norway who was opening up his lift pump and filter for additional fuel flow - why not just cut to the chase and order a high performance pump and filter system?

I found this.. any thoughts on the spec for delivery and also the price! ( of course time is money too)

I can't imagine a serious amount of increase can be gained by opening the inlets my a few MM, and then you are limited by the GM filter system.

I initially thought why not just run into two filters in parallel.

But this has the pump, air and water separator and fuel heater all built in.

They talk alot about filtering out the air from the fuel, but logic tells me that that is probably way down on the list of things that could affect performance -- any air should be separated in the filter.

Just a thought
Wayne

heres the link: http://www.dieselspecialists.net/fass.systems.htm
 

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Here is my opinion.

The FASS seems overkill for the 6.5. Other 350?, 500 HP +... applications it is probably a real improvement. What most 6.5'ers want is a good reliable affordable LP with a bit more performance and flow through on failure design. 10 micron's is not quite filtered enough. IIRC the stock filter is 5 microns.

I don't think air is a major problem until you get to high flow turbulent conditions. Maybe big tanks slosh and aerate I don't know.
 

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Air in the fuel is more prevalent than you might think,. pittsburgh diesel sells a device that has shown a diffence on the dyno for large diesels,.by removing the air in the fuel they claim less smoke and better power and economy,.
As for opening up the 6.5 fuel system for more flow,. i,d need to see a dyno run comparison to see if that was a really useful option , seems there are plenty of 6.5's 'turned up' with chips intercoolers etc,..
i haven't heard or read yet of a 6.5 motor hitting the wall(figuratively speaking) for lack of fuel flow,.'course i haven't read much about any large horsepower 6.5's either yet, These blocks are delicate enough with factory settings let alone asking for a couple of hundred more horses,.
be interesting to see if this new international 6.5 clone block could be built for some serious power,.
nick
 

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This still doesn't deal with the issue of opening up the inlet on the Injection Pump. You can free flow all the fuel in the world "to" the injection pump, but if it can't get "in" then it's not much good.

At least that's the way I see it.

Dave
 

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Two methods for increasing flow - increase area of conduit or increase pressure, or both.

Negative benefit being, the DS4 cannot take much pressure increase without effecting internal operation and increasing fuel return volume.

This may be good for cooling the PMD, but who is still using a Pump Mounted Driver?

Show of hands, please?

The second negative benefit is increased fuel return aerates fuel in the tank, which is a major consideration in the on-going discussion, 'n est ci pa?

Main consideration is to maintain sufficient input pressure at idle and full throttle - if the LP can supply 7.5psi at full throttle and misfire occurs, then opening the conduit will cure that.

Second main consideration is, the DS4 can get you home when the oem LP fails, as the valves are pass-thru - put most aftermarket fuel pumps in LP service, and failure will strand you.

The oem LP's are self regulating, electronically - if full throttle supply pressure is dropping, the IP is flowing more fuel than the LP can supply.

If the reduction in pressure is internal to the IP, the conduit requires increasing - proof of that would be supply pressure would not drop when 'fishbiting' occurs.

If supply pressure drops, that would indicate LP cannot supply required volume, and solution would be greater volume, not greater pressure

IP guys like Diesel Pro can provide required input pressure limits
 

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gmctd;1590343; said:
...but who is still using a Pump Mounted Driver?

Show of hands, please?
:ro)
 

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gmctd;1590343; said:
...but who is still using a Pump Mounted Driver?

Show of hands, please?
:rockit:

Until that PMD does this: :nutkick: or :Wedgie:

then probably going mechanical...
 

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I'm planning to replace the stock lift pump on my Suburban with a Walbro 393 pump. I will install a regulator between the injector pump inlet and the return to bleed excess flow back to the tank. The big benefit to this type of setup is that unless the filter is plugged, you have normal fuel pressure at the injector pump under all conditions. With the stock setup (or a FASS, Holley Blue, whatever), the filter acts as a false load on the pump/regulator unit. You get full pressure up to the filter, but pressure after the filter will drop under load. Move the regulator so it's after the filter and the full pressure of the lift pump is available to push fuel through the filter, keeping pressure at the injection pump at the desired level.

I've got a similar system with a bigger Walbro on my Dodge and the fuel pressure gauge is now boring. It works amazingly well.

I'll be really amazed if it keeps the PMD alive, though. More fuel flow won't do a thing for the PMD when the engine isn't running.
 

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Believe it or not I actually dreamt about this stuff last night.

Can you run 2 lift pumps in a row or will one just defeat the other?

This is what I was dreaming about, or thinking about when I couldn't sleep.

Dave
 

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The H/O pump I'm running thus far has sufficient delivery to meet all demands, except the hardest acceleration demands, I haven't towed big with it yet, but from watching the gauge installed to monitor IP supply (lift pump output), even though lift pressure under max acceleration load drops to .5 psi, recovery is almost instantanious once engine settles in at desired cruise speed pressure recovers to maintain 2-3 psi.

The OEM pump would hover 0-.5 psi for a very long time 10 sec or so, and only maxed to 5 psi even at idle; cruising with just a empty truck load 2-4 psi was avg pressure, towing light or heavy 70-75 mph 1-3 psi once eventually setting in from acceleration demand.

The numbers I see from the Heath H/O lift pump at idle 8-10 psi, 4-6 psi at cruise unloaded, 2-3 psi running hard/moderate tow (4000# 6x12 enclosed trailer & 75mph) after acceleration settles back up from .5 psi low point.

I'll be moving my backhoe to camp 150 miles away next month (18K loaded trailer); if I find from that run I need more fuel than what the single pump will provide I have decided to install a 2nd Heath H/O pump and have it manually switch controlled to be powered when/if I need the extra fuel.

The reason for going with these, they are internally pressure regulated, flow thru on fail, and internal design incorporates a check valve style outlet diaphragm so I will not have to provide a valve to prevent backflow, as I would have had to do with my original thought using a GM & Cummins dual pump set up. Plus 2 pumps of same design will operate at pressures/delivery comaptable with each other, you will want to run with a real time gauge to monitor lift pump pressure between monitoring EGT (work), and lift pump pressure to know when to engergize the 2nd lift pump.

I'm calling EGT work in this instance as if you are at max throttle request (APP to floor), and you have lift pump providing sufficient delivery to the IP one would expect EGT to also increase. What I was seeing on earlier heavy tows with GM pump , I was 2500 rpm, 60 mph or so on hill climb, fuel demand 80mm as seen on scanner, EGT post turbo 750F, but no more increase in speed/EGT/boost, but key was also only .5 psi lift pump pressure.

This led me to the feeding the beast mods, which haven't been fully tested with a heavy load yet, seat of pants, moderate towing, and gauge/scanner comparisons I'm seeing the desired result of more fuel, now I just need to confirm my theory 2 pumps may be needed in SOME cases. This will be next step before looking at propane augment, I just think some of the 6.5s/DS4 limits are just from running out of fuel volume supplied to the IP, not that the IP is incapable of delivering enough, the 80mm+ reflashed PCM request seen on a scan tool, is just that a request for that much fuel not what is actually flowing through it under loaded conditions.

The Cummins pump my 1st consideration for more lift fuel, is not a flow on fail design, and makes pressure/delivery above what GM style pump delivers; for 90% of 6.5 owners a single H/O pump like Heath or Kennedy sell will be sufficient, I think Westers and maybe some others sell H/O pumps, just remember any pump you choose needs to be flow thru on fail, and be Diesel fuel compatable .

The Heath pump I have 1st hand knowledge that it works, the Kennedy pump should work well as well as it was originally sized to feed the DMAX, it is plug and play and powers it's pump via a relay vs the OPS power circuit the stock setup uses; so in that area if you don't do trons well enough to make your own relay setup, the Kennedy kit is the way I'd go for single H/O pump setup
 
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