I will be adding a second fuel tank to my 2004 Dodge Ram 3500 pickup truck with a 325 hp Cummins 5.9L I6. What I know about the truck is that there is a 35 gallon tank and it has the fuel pump and sensor module all mounted on the top of the tank as a single unit. Costs around $340 from a dealer to buy that pump/sensor unit. But I really just need any-old fuel pump, as long as it supplies enough (a) pressure and (b) volumetric flow rate to do the job similar to the stock fuel pump. (and as I am finding out, not too much, either.)

I will install two manual 3-way valves (one for the inlet, 3/8 in, and one for the return, 5/16 I think) or it might be better to install a 6-port electric valve. Pollak makes the 42-300 electric kit for around $70. Tempo sells some brass 3-way valves. Anyway, the pump needs to be installed at or near my new aux tank, and I was going to hook into the two OEM fuel lines very near the fuel filter and injection pump. Any idea what pressure or delivery rate (in liters or gallons per hour) would be for this truck? Anyone use a fuel pressure guage on their stock fuel system?

If I knew the specs for the OEM fuel pump, I could match it!! What I see in the aftermarket is primarily the FASS fuel systems, which are hugely over the stock requirements, and some 255 Lph fuel pumps made by Walbro. Even the Walbro inline pumps are more than the stock pump puts out, because of the way they tell you to use a feedback loop back to the tank filler hose in order to not force more fuel than the engine wants. The output pressure would go way up for the Walbro 255 Lph pumps, so this is reduced by sending the excess fuel back to the tank. Duh. See http://www.glacierdieselpower.com/pr...?pf_id=3910345 for one of the Walbro examples. Notice the "bypass valve" is mandatory.

Well, so, I would like a low output fuel pump, similar to the stock pump, merely to suck fuel out of my new aux tank. How to go about finding that is still a mystery.

BTW, the two tanks will have different types of diesel in them and should not be mixed to a significant degree.

 

The problem with the OEM pumps seems to be that they are running maxxed out all the time. At WOT conditions, the pressure drops alarmingly low, if horsepower mods are made to the truck, the OEM pump can't keep up, and the lifespan of these pumps is (in my opinion) way too short.

The beauty of the Walbro pump is that:
1) it's made to pump far more fuel than our trucks require, so it isn't overworking itself all the time.

2) it's far quieter than most aftermarket-style pumps.

3) it is robust enough to support any horsepower upgrades you may make in the future.

4) you may think it's "wasteful" to be simply pumping 75% of the fuel through the system to return it back to the tank, but really, what is it costing you?

I am a 12 valve owner, so unfortunately I miss out on all the electric/booster pump dilemmas but I work on these trucks daily, and get to see what works and what doesn't. I follow these threads often, and believe the Walbro system to be my favorite.

 

Sure, I know that more fuel is better. I respect that, certainly. I don't doubt that I will use a Walbro or FASS someday. But I just need to maintain near-OEM specs for this application. It boils down to what will make the customer happy, and it just so happens that I need the lower stock pressure and pumping capabilities.

Buying the entire OEM pump assembly just doesn't seem to fit into the auxiliary tank I will be using. Too bad it's not an inline design, or I would have already gotten one. Any hard figures on what the OEM pump is rated for, or who makes it, etc.? Or is this info in a technical bulletin somewhere?

 

My 03 OEM stuff is inline, and is coming off after Christmas, as I am installing the Walbro from Glacier. Too many failures on the OEM stuff to even THINK about installing it, much less BUY an OEM replacement. If you look at the install on Glaicer's website, you will see that it is very simple, VERY effective, and will outlast any Dodge OEM LP.

Now, to answer your question about pressure. The stock LP runs around 10-12PSI, or at elast should, but normally does not. Mine runs at 2-3 PSI at idle, and 0 PSI under boost Yes, I have a gauge on it. The IP pulls fuel out of the filter cannister, and supllies fuel to the rail and injectors and something around 26,000 PSI. SO, when your stock LP starves fuel to the IP, the IP burns up, and you are out BIG bucks because of the less expensive and inadequate OEM LP. So, most people upgrade to an aftermarket LP (like the Walbro from Glacier) to keep from burning up the IP (also known as the CP3) Oh yeah, you ALWAYS here of the OEM Dodge LP going bad, but hardly if EVER hear of the Powerstroke LP going bad, which is basically identical to the Walbro.

 

I tested mine back in January. The way I tested it was to drain the filter housing, leaving the filter in, until it was just slowly dripping.

Then I would turn the key on and click the stopwatch to record the time
the pump run. I turn the key off in 13sec and recorded 940ml = .94liters.

This calculates to about 69 gal/hr. More than I would have guessed.

Of course this is against very little back pressure as it is just going thru some
lines and the filter.

A more meaningful test would be to check the flow at the return line but I
didn't bother to do that.

My pressure gauge was showing 7psi at the cp3, my pump being the in-tank
model.

I'm now using the Walbro 391 GDP setup and it shows to put out about
50 gal/hr at 17.5psi back pressure. So you can see that no matter what
pump you use the vast majority of the fuel is returning to tank. I am told
that this excess fuel flow is needed to keep the injector pump cool.

You can run your own tests and see what you come up with.

Larry

 

I have a 60 gal spare tank in the back of my old welding truck ( '91 Dodge 250 Diesel) I installed a 3/8" line from the bottom of it and plumbed it into the fill pipe of the regular tank. Have a electronic fuel swithch on that line. When my main gauge shows low, I hit the switch and it just gravity feeds into the trucks stock tank. I then when driving ,keep and eye on the gauge and when just about full I turn off the switch. Takes about 1/2 hour to 45 minutes to auto fill while I'm driving. No second gauge, no pump and works fine since '91.