Patrick Campbell

For months I've been planning on doing this. Not really a huge deal but takes some time. I am also an idiot with a wrench but did this all by myself so that should say how relatively easy it is. Replacing the fuel tank to VP44 lines with 3/8" J30R9 (the expensive stuff), put a gravity feed fuel draw from the tank, fix the fuel level sender, mount the Carter pump back on the frame rail AFTER a huge Racor 120 GPH fuel filter/water seperator. Here's how it went:

Saturday morning woke up and it's POURING. No choice but to do it anyway, since this is my only weekend where I have plenty of time. 3 day weekend and my girlfriend is working all 3 days so nobody to ***** about me being greasy. If you weren't sure already, diesel + water = SLIPPERY. Made it pretty messy, not fun, and a bit of a pain in the butt but it was doable anyway.

I'd planned it out so I'd have just 1 gallon left when I got to my friends house (I live in an apt. complex) so of course, about half a mile away from his house, I ran out of fuel... so I pushed my 7000# truck down the block while getting a few funny faces, and got to work.

After making sure I had all the pieces, I took off the stock fuel filter assembly and pump and blew air in the lines to push the diesel in the lines back to the tank. First bad idea... the air had nowhere to go and I got a waterfall of diesel shooting back in my face. Woops!

Next step remove the tank. Knowing it was pretty darn empty, I just put a huge jack under the center of the tank and unbolted the tank straps (2 total, the other end of each strap is hooked into the frame). When it is lowered a little bit you can remove the fittings. They are "quick disconnect" which are not that quick and honestly they make me worry a little just because doesn't look like they'd seal well ... I'd much prefer a single single barb and a nice clamp but whatever. Of course I partially broke the fuel level sender connector because I do this with all Mopar "quick disconnect" fittings

Opened up the top of the tank with a Horror Freight strap wrench with no problems at all to find 2 gallons of cruddy looking fuel. I used my stock pump to bilge it out and put it into a container and then drilled a 7/8" hole into the bottom of the tank and threaded a $5 1" bulkhead fitting into it with a Viton o-ring on the inside of the tank and a huge washer/nut on the outside followed by a nice 90 degree smooth bend 3/8" NPT fitting.

When it came time to replacing the fuel level sender, the more I looked at the stupid fuel tank "module" the more ****** off I got, so I did the logical thing.... I took a hacksaw to it right below the screw-on top. The only thing its used for now is for the fuel return. As for my fuel level, I haven't had one since I got the truck so I'm not going to miss it... and plus now I'll show a permanent full tank of fuel I remembered to put a plug on the stock intake port so crud doesn't get in.

Mounted this huge Racor 6120 filter http://xj.cdevco.net/auto/fuelsystem...N-HIGHFLOW.JPG onto the frame rail and then *AFTER* the filter, the stock Carter pump. I used a Holley shut off valve before the filter to make it easier to change filters, and can also be used for security.

Finally ran 3/8" NPT hose to the VP44 where I used a 12mmx1.5mm to -6 AN aluminum fitting followed by a 90 degree fitting, followed by a -6 AN to 3/8" NPT with 1/8" NPT pressure port, followed by a 3/8" NPT single barb fitting. Ran the 1/8" NPT to my fuel pressure gauge with a hose so the electrical sender isn't right on the motor, also put a snubber in there.

1 thing I have to check is the voltage at the pump at idle. I just extended the electrical connection from the stock pump-- using a relay and some nice 14 or 12 ga wire might be beneficial but at the same time, there is a seperate relay in the fuse box for the stock pump, it might be overkill no pun intended.

The only problem I have is that the pump hangs dangerously low. This thing is 14" long. Today my friend is going to build a bracket for me to lift it up maybe 4" and then put some skids around it. Now for the results...

Previous with the stock setup and a brand new Carter pump measure *BEFORE* the filter... don't want to know what it was after the filter.
IDLE 12
CRUISE 10
WOT 8

Post-results are *AFTER* the filter... guess it's not very restrictive
IDLE 14
CRUISE 13
WOT 12

Plus, MUCH smoother idle, MUCH nicer start ups and shut downs.... This is on a bone stock truck still, I'm really happy with the results. I imagine I will be getting increased fuel mileage too. Thanks MLR1 and Haulin for the help,advice and inspiration!!! I'll get pictures later but it's the same idea as these guys have in their galleries...

Patrick Campbell

Guess I spoke too soon, I filled up the tank and now I am at 14.5 idle, 14 cruise and 13.5 WOT.

wannadiesel

So now your FP gauge also serves as the fuel level gauge.

Patrick Campbell

Pics here : http://xj.cdevco.net/photos/fuelsystem/

Relocated the pump up in the fender... lost that extra little bit of pressure because I am above tank level here, but still at 12+ PSI WOT. Kept the pump where it is, pretty far forward on the inner frame rail... might relocate it but for now, I think it's good.

Only problem now is I am dripping through the threads of my bulkhead fitting

Gunna try to figure out what I can do to fix it without dropping the tank again... maybe a Viton o-ring on the outside.

RTillery

When you run your tank down fairly low, are you worried about uncovering your bulkhead pickup fitting on accelleration or decelleration? With that long tank and no low spot for the fuel to pool and hold in, won't you likely be sucking air into your modified system? Not knockin, just asking.

joefarmer

I too gutted the stock system. In my case, it's a 3/8" fuel line thats held within 1/8" of the tank bottom. I recently put in 26.458 gallons in my shortbed tank, no problems with fuel starvation or sucking air through the FASS system.

njoverkill,
Excellent description and documentation! Looks great!

brandon.

cditrani

I assume the tanks are baffled to prevent, or at least minimize this.

Nice job! You get a real sense of ownership with the truck after you spend a day on your back soaked in diesel. I'd love to do the bottom feed once the weather gets warmer, but so far I have no indication that my stock fuel pickup is a problem.

Mcmopar

The tanks are NOT baffled.

Vulcan

I reloacted the stock LP to the frame near the tank, removed all the banjos up to the VP44 and used all straight M12X1.5 to 3/8 barb fittings (no adaptors and 3/8 30R7 hose and made nice smooth bends and my numbers are as follows;

Idle - 15-16
Cruise- 14
WOT- 12-13

Stock Carter pump with about 4K on it, stock engine with BHAF.
E

2500CTD

Where would you want the bottom pickup? towards the front of the tank, being the truck is higher in back, the middle, or the rear of the tank to make sure its covered under accelleration?

MLR1

You want the fitting in the middle. If you look close at the tank there is a low spot in the middle right under the stock fuel module. As for the pickup going dry I addressed this in the thread I posted yesterday. Here is the link https://www.dieseltruckresource.com/...threadid=61840
I have a pic in my gallery of the fitting installed in the tank. You can look at to give you an idea on placement.

HTH.
Max

Patrick Campbell

Preliminary fuel consumption tests are good. I did 300 miles on under 15 gallons. Thats about 20 MPG with aggressive city/highway driving, boosting 20 PSI and flooring it... often.

Imagine if I could keep my lead foot off the hammer ??