So I moved my whole aux tank setup from my 04 to the 15. RDS 60 gallon, RDS Diesel Install Kit, screw on filter/water separator, tank selector switch for cutoff, and electric fuel pump. The first pump was an el-cheap-o but lasted about 8 years. The newer one is a Mr. Gasket 12D Micro Electric Diesel Fuel Pump. It is supposed to run 35 GPH.

Running empty it will fill the truck over time. Last weekend I was hauling cows all over the place pulling a stock trailer. The pump could not keep up with the rate I was burning fuel. It is not always easy to get my rig into many stations so I need to be able to keep up with fuel consumption of the truck from the aux.

Anyone want to recommend a pump that keep up? At 35GPH that should have more than capable.

 

My transfer flow tank is published as a 1 gal/3 min pump.

That obviously is 20gph and it more than keeps up.

My experience tells me that your tank set up is probably caught in a vapor lock. The transfer flow tank I have is vented, allowing the air pressure built up in the factory tank from filling without the fuel cap off to vent.

Try this, run your pump with your factory fuel cap off, make sure your truck tank is below half full, and see if the flow returns. I'd suggest pump times at 20 minutes to allow the air pressure to equalize also. I usually run with my factory cap loose, on, but loose. Sometimes when I stop for a break I remove my fuel cap and there is still a pretty strong surge of air that puffs out.

I write this because it appears that your set up may be a closed non vented system but I could be wrong, something to eliminate at least.

 

Strange, on my dads truck he just uses the gravity feed and his works just fine that way so you must have some restriction somewhere.

 

Does the gravity feed work because there is no vent?

Likewise, would the factory tank overfill and come out the fill cap if it were vented?

Does he leave the aux fuel supply free to flow all the time or is there a valve to start/stop?

 

the stock tank has a vent.. it has to block the overfill as it is lower than the top of the filler neck.

I leave my electric valve (upfitter) on all the time, the stock fill pipe is full.
because it is not a vented cap, there is a small air pocket behind the cap.

the stock vent should block any overfill leak.

 

Is the truck tank non-vented? My aux tank is vented. I had thought about that but thought the factory truck tank was vented. I will certainly try your suggestions.

 

the stock tank is vented..

 

I have used RDS tanks, both gravity and with fuel pump since 2004, and I've never had a problem with replenishining faster than usage. I've seen the mileage goes as low as 7.5 mph when pulling the 5th wheel going against 25-30 mph winds. Still replaced fuel faster than needed.


With my current truck I use Airtex pump, Wix fuel filter/water separator, and 12 V. cutoff. AutoMeter fuel gauge for aux tank is on the dash.


I'm sure you've checked for partial fuel line blockage, or kinks. Could your fuel filter have an internal restriction? Is the fuel pump not working at full specs?


I'm sure you've thought of these possibilities, just thinking out loud. Under normal towing conditions(light to no wind) my system only needs a few minutes to raise the stock fuel reading by about a quarter of a tank.


Let us know what you find..............


Jim

 

This is the first time I used the 2015 to haul loads where I needed to pump more fuel. It could very well be the internal filter on the elec pump. Since I have the WIX, I will just removed the little tiny thing on the fuel pump. I have to believe it is either a restricted filter or just a poor performing pump. The WIX is new and the pump/filter is from my old truck. I will check them out.

 

I don't know how your system is set up, but a few ideas.


Of course my truck is a chassis cab, so it has a rear 40 gallon tank. My RDS aux tank sets just behind the headache rack on top the flatbed. All the aux components are close to the front and underneath the bed with a fuel line going all the way back to the stock tank.


I can just disconnect the fuel line at the rear and check the fuel flow. If sure your situation is different, but could you do the following:


Disconnect the fuel line from the fitting at the stock tank and place a coupler in the fuel line with some more fuel line on it and place the end in a clear jug and turn the pump on. This would give you a way to watch the fuel flow and time the delivery rate.


Did any of that make any sense???


Jim

 

I believe the stock tank vent is one way. It allows air to come into the tank but not allow air out. If it can't "ingest" air to replace the fuel used, a vacuum would be created and it would collapse the plastic fuel tank.

Also, I would think it it allowed air to escape, it would throw a code similar to the P0442 I have seen on cars with bad gas cap or gas cap left off.

 

Yeah, I can try that. I have to get under there an remove the little filter screwed into the pump anyway. Simple as how long does it take to fill a quart or a gallon and do the math from there. Thanks

 

I don't really know for sure and I trust Sam and all, but, when I pump fuel from my aux to the truck tank and then pull over and remove my fuel cap there is a pretty strong poof of air that comes when I break the cap open.

The rush of air tells me that the air displaced from filling the tank has no way out, a slow way out, or it just stays pressurized until I burn off more fuel.

Any one of those three things is possible. That's all I am really sure of so when I pump fuel from my aux tank I try to limit it to 1/4 tank at a time.

 

I can tell your pump is different than my Airtex. My pump has no filter on it, just a pump. But the outlet side of my pump goes in to my Wix fuel filter/water separator. This Wix unit is just about the same size of the Motorcraft oil filters our truck use. It has a petcock in the bottom for taking fuel samples. I drain it and the other filter under the driver's seat ever so often in to a glass jar. I've never had any dirt or water. I guess than means the filters are working and I've been lucky enough to not have any water.


I've cut the Wix filters open with a hacksaw to check the filter media, always looks like a new filter. I've really liked this setup.


Just thinking are you getting a restriction from too small a filter or a partially clogged filter?


I'm sure you will get to the problem soon.........


Jim

 

Thanks guys. I will take a look at it this weekend. My WIX filter only has maybe 100 gallons pumped through it since I put it on. I am thinking the little filter that came on the pump might be a restriction but it is a "diesel Pump". Would have thought they would put the right one on there. Don't need it with the WIX setup anyway. I will get a gallon jug and measure how long it takes to fill it up and go from there. I can see another diesel bath coming. lol