HID,
Thanks for clearing that up.
I'm gonna think about this design hybrid a little while before I do anything though.

Chris

 

Thought #2 (yeah, it's been one of those days):

What about the fuel return line. I hate shutting down to fill up. I was wondering/thinking that if someone was to modify the FASS return line, I wonder where would be the best place for the warm, frothy fuel to return to? Would it work best to have another low entering tube or does the fuel always return with enough force to negate the benefits of not spraying the return fuel?

Something like

might work to plumb both of the fittings in the top of the tank. One for pickup and one for return. Maybe locate the pickup in the side of the take where the stock filter/sender is located and put the return in the very rear of the tank, somewhere low too. This way it's not immediatly sucking up the warm fuel.

What hose would last inside a take of diesel? Would rubber eventually expand and fall apart? Can these adonized aluminum pieces work inside the tank without disintegrating over time?

brandon.

 

Air brake line, nylon with teflon inner liner, any size you want.

 

At least I know the 99 does. There is a 3/8 fitting with a return hose that clips to the side of the fuel module in your tank. Look at the top of your module and you will see a plastic plug with a rubber cap on it, That is the one! No need to cut your Fass into the Vent line. With that said Mine is cut into the vent line because I did not realize this until I took my module apart. I then used the hole the spare was in when I repaired my module. I now have the supply and return in seperate holes and the Fass still in the vent line. I may change this the next time. I think I will fabricate a new fuel module once I decide what features I want to include.

 

What about just returning the FASS through the factory pickup tube when you move to the better pickup at the bottom of the tank, or through the plug in the fuel module Raw Power mentioned?

Chris

 

Thanks Raw Power, I wasn't aware that I'd have an extra fitting on the top.

Chris,
Most likely I'll end up buying enough parts to do a pickup thru the side and enough to patch the filler neck hose back to stock. I thought about returning the fuel into the stock pickup, but I'm pretty sure there's a check-valve in that assembly.


brandon.

 

Brandon,

I tried the firewall style fitting you attached (AN8) and attached it through the top of the tank aft of the sender, and made up an aluminum tube with a crowsfoot on the bottom of it and it actually touches the bottom of the tank. I did this to see if there was any difference over using the stock supply tank fitting which there wasn't but thats not why I bring this up. One of the problems I noticed was cavitating the fuel pump in hard corners when I was under a 1/4 tank of fuel. It would also cavitate when launching right at a 1/4 tank. Also it gave a hard starting issue once after being parked on a steep up hill in downtown Seattle and the tank was 3/4 full. This was done while using two Carter fuel pumps that I don't really use anymore. Instead of just capping that fitting off I decided to used it for a return fitting for my fuel system. If I where in your shoes and I wanted to use this fitting for a return I would attach it from the top of the tank and not attach a hose inside the tank just a seal washer and a AN nut to it.

 

Thanks Opie! That's a really good snippet of info. I think MDW posted awhile back that the stock pickup has a small reservior that holds enough fuel in a low fuel situation to turn the corners and stuff like that. I wish these tanks had more of a sump, I think that would help the prime problems I have. Last night after the pull mine cranked two revolutions and ran. My buddy's jaw about hit the floor cuz he's used to cranking 30-45 seconds multiple times. I still haven't made up my mind. There's also a chance the intank filter/screen is dirty enough to affect the flow. Or the check valve isn't working right. Hmmm...

brandon.

 

I took my fuel module out to fix the sender and found holes in the rusty supply line. Anyway after staring at the thinking about the thing for awhile I decided that the module was actually pretty well designed. If it was made from better materials I think it would be great. The quick connects on top are probably a bad idea and I wish I had not fixed my module using new quick connects. I am going to make new parts to eliminate them this time around, possibly a whole new module if I can talk someone at work into helping me out again. Anyway, I am replacing all my lines and fittings this weekend using some special Goop we use on Diesel gensets at work I want to try and eliminate the lines as a source of air.

With all that said, the problem is I am losing prime because of a small air leak, A check valve after the Fass would probably keep the injector pump primed, sort of a band aid. I saw some nice billet aluminum ones on the net for $60.00. Anyone think this is a bad idea or have a reason I shouldn't do this?

Also thinking of Getting a custom made aluminum tank made to replace the plastic one. I could have a side or bottom pickup with a nice deep sump made but I worry about the welds breaking or some other problem related to hard miles on the bottom of the truck. Plastic should out last me but not so sure the aluminum tank would. Any input? Cost not an issue as I can have it made for cost of material at work.
Thanks

 

You may want to look at www.transferflow.com for ideas on 'midship replacement tanks' before building yours. I'd be cautious about making the sump lower than the framerail without a proper skidplate. I think I'm more confused now then ever.

brandon. -DD

 

ASTAR and joefarmer,

When you have a hardstart condition have either of you tried applying a little throttle. A couple years ago I tried running 30+ pounds of fuel pressure I ran into this problem and by adding some accelerator pedal while cranking the truck would then start.

 

It had crossed my mind, but I thought these trucks were completely electronicly controlled. I'm gonna try your method tomorrow.

My hard start goes like this... I jump in (fuel pressure 0#), wait for the 'wait to start' (fp 10#) and start cranking(fp 5#). 9 times out of 10, it doesn't start within 20 seconds. Wait 2 seconds and it fires right up like nothing ever happened.

brandon.

 

The sump on the stock tank is below the frame rail...

 

I installed my FASS last Saturday, and was considering moving the pickup hose to a side or bottom port. I discussed this thread with a friend who currently drives "the big trucks", and has been an ASE certified mechanic. His concern with having the port on the bottom of the tank is with the DOT -- they do not allow any ports coming out of the bottom of fuel tanks (problems with them leaking and/or breaking off). Has anyone checked with state/federal regulations regarding the port being located on the bottom of the fuel tank? Just wanting to be sure before "drilling that first hole"...

 

to be legal with DOT the bottom port has to be protected. On an alumimum tank it consists if a small u shaped piece welded to the tank. Look at the bottom of any big truck and you will see what I mean. Contrary to what he says, almost all big trucks feed from the bottom of the tank.