2nd Gen Non-Engine/Transmission Fuel tank sending unit - rebuild / rework

[HoleshotHolset]

First of all - I don't claim to be a fuel system delivery expert. At most - I'm a 'parts changer' when it comes to anything before the lift pump...



Recently, I noticed that my truck was dripping fuel - on closer inspection I found a steel feed line along the frame that was badly rusted. So, I removed 4 of the bed bolts and loosened the back two so that I could lift the bed with my cherry picker to have a look at replacing the lines from the sending unit all the way to the lift pump. The sheer number and intensity of the cuss words that followed after I saw the sending unit would impress a drunken sailor.



So - I did what anyone would do... yanked the tank and pulled the sending unit out. There really isn't much to it. Other than a float valve at the sump that prevents you from drawing the fuel tank completely dry - it isn't complicated at all. There is an auxiliary port on top that I chose to reuse as the new return - that will dump fuel into the middle of the unit just like OEM. The OEM steel feed/return lines were removed and that hole plugged off with a PVC pipe plug.



I then fabricated the piece d' resistance from hardware store copper/brass fittings. The big piece is an air chamber with a 1/2" sweat fitting - interestingly this thing necks up to 1" copper pipe... which fits PERFECTLY into the OEM rubber grommet where some kind of vent hose was. (My fuel cap vents to atmosphere - so I don't need another vent. ) The other parts are self-explanatory... I sweat them together with common plumbing silver solder and Nokorode paste flux. I was hesitant to sweat the copper to the brass hose barb fitting, but it worked out just fine. (Excessively good preparation is the key to sweating fittings!) I then took socket heated up with a propane torch to make the hole for the sump tube in the plastic... The whole thing is able to slide up/down just like OEM - to allow for the poly tank to flex, etc.



Concerns - will this setup actually work? Will the lift pump be able to draw fuel through a 1" pipe as opposed to the OEM 3/8"?



I'm going to give it a whirl after I replace all of the steel lines and the horribly rusted out filler neck.



Comments, suggestions, etc...



Thanks,



Matt

 

[HoleshotHolset]

... more pics.



The filler neck is completely rotted out. I'm not going to try to replicate that piece, though.



Matt

 

[Fishin Guide]

The only concern I would have is with possibly losing prime. With such a large diameter, it's possible that it will have issues. I have seen it with low volume pumps and 1/2" lines at low fuel levels.



The fuel literally drins back into the tank and is replaced by air.



Dave

 

[fortunate1]

That's a cool fix, if those lines are rusted. I think it'll work fine. Even when the return line rots & leaks air, the trucks will still start - maybe needs an revolution.



What mine is doing relates to the two thin metal "slide guides" that allow the float to ride up and down with the fuel level in the tank. The slot in each of the slides is badly worn from the steel screw that keeps the float centered. Did you notice any wear in yours? I'm wondering if there is a fix for that, or if I'm going to have to buy it from *****.

 

[MMoroney]

What mine is doing relates to the two thin metal "slide guides" that allow the float to ride up and down with the fuel level in the tank. The slot in each of the slides is badly worn from the steel screw that keeps the float centered. Did you notice any wear in yours? I'm wondering if there is a fix for that, or if I'm going to have to buy it from *****.

I think I just "fixed" that on my '96 this weekend. I measured the depth of the tank, subtracted about 1/8", and adjusted the sliding pickup to that depth. I drilled the 3 mounting holes out and used screws with washers/locknuts to hold the sliding pickup in place. Hopefully this is a good fix, although I had 3/8 of a tank when I "fixed" it, and then filled it up to check my new fuel gauge sending unit. Not sure if there will be any problems when I'm closer to empty. If anyone knows why this won't work, please chime in before I run out of fuel. :{



Matt, I agree with you that the lift pump may have issues sucking fuel through that one inch pipe, unless you have a massive aftermarket pump. Please keep us updated. - Mike

 

[rbattelle]

Wow, that is a pretty cool fix. I like it. How's it working?



-Ryan

 

[WDixon27]

i put some washers on mine when i had it out fixing the level sender, i did the same thing when i did the sending unit on a buddys dakota which looked almost like the same unit

What mine is doing relates to the two thin metal "slide guides" that allow the float to ride up and down with the fuel level in the tank. The slot in each of the slides is badly worn from the steel screw that keeps the float centered. Did you notice any wear in yours? I'm wondering if there is a fix for that, or if I'm going to have to buy it from *****.

 

[HoleshotHolset]

I've got the new $140 filler neck in stock, so the whole mess is going to go back together soon.



I'll keep ya'all updated if it works or not.



On edit: My sending unit (or fuel tank module... to each his own) also had a lot of wear where the screws were rubbing. I filed down the high spots and am not going to worry about it.



Thanks,



Matt

 

[Matthug]

Ha, that filler neck is intact compared to the way mine was. Unless you had a almost solid stream of fuel coming out when you were filling... . boy did I get a surprise first time I filled up after buying the truck! I cut mine off with a sawzall right below the small tube air vent, found a radiator hose at autozone with the same contour (about a 75 degree angle) and inside diameter, hose clamped it in place of the rest of the metal (or lack thereof) pipe.

 

[HoleshotHolset]

Update: Redneck Engineering prevails!

Many hours and a few select cuss words later and she's on the road again.



I installed all new 3/8" and 5/16" steel feed/return lines and USCG rated rubber fuel hose. (There are double flares and brass unions at the joints in the hard lines. I couldn't find nor wanted to deal with lengths of hard line longer than 60"... )



I've put about 100 miles on it Sunday night and yesterday and all is well. I did notice that when I went to pass someone on the highway yesterday AM, the truck stumbled a bit with a little less than 1/4 tank of fuel. So - the tube isn't down as far as it could/should be... or it is loosing suction for some reason. I romped on it numerous times with a full tank and she's back to her old self - if not with more power now that I'm not sucking air. No drainback issues so far - knock on wood. It sat overnight and fired right off the next AM.



So far, so good.



I cut out a portion of the bed support in case I want to get back in there to swap out the sending unit. I cut the support vertically with a Sawzall and then swore at the spot welds with a prybar and a hacksaw. I don't want to drop the tank again - it's not a big deal to do, but this truck gets used so little as an actual truck - I'll deal with a modified bed if push comes to shove.



On edit: That big clamp on the 1" pice of copper pipe is there to keep the whole mess from falling into the tank. The fit between the pipe and the grommet is snug, but I didn't want to tempt fate.



Matt

 

[Fishin Guide]

Looks really interesting. And on the cheap for the module parts. I know you paid through the nose on that marine hose though!!



I am currently working on a modified module. i hope to have it done in the next few weeks.



I have removed the factory plastic connection and grommet and I am going o get a piece of round stock machined to fit the hole. NPT threads top and bottom and some air brake hose in the tank. A bulkhead fitting in the bottom of the module and -8 lines to the lift pump. 12V pump engine mounted.



Thanks for sharing the pics! I look forward to doing the same for others!



Dave

 

[HoleshotHolset]

Hey, Dave:



Marine hose was $20 for 28" of both 3/8" and 5/16" and 4 all-stainless clamps... http://fostertruck.com/dodge/default.htm



I like your idea better, but I don't have access or the time to have custom stuff milled up. I hope your setup works out and that mine will hold me over until yours is available. I'll be a beta tester if you'd like.



Are you going to run the now infamous Walbro electric pump?



Matt

 

[Fishin Guide]

Hey, Dave:



Marine hose was $20 for 28" of both 3/8" and 5/16" and 4 all-stainless clamps... http://fostertruck.com/dodge/default.htm



I like your idea better, but I don't have access or the time to have custom stuff milled up. I hope your setup works out and that mine will hold me over until yours is available. I'll be a beta tester if you'd like.



Are you going to run the now infamous Walbro electric pump?



Matt

I am actually just trying to steal whatever info works best from others. I don't have access to a lathe either, so I am trying to get friends to make this little thing up. There was a guy selling module fittings at one time ion the TDR, but I cannot get into contact with him. So, on to make my own.



The rest, others have suggested and or it just looks right.



I am running a 12Valve lift pump off the cam. -8 line is way bigger than what I need as it cranks out 5xx hp on the stock lines and never drops below 22psi no matter how hard I try to mat it. So, -6 would be a better bet, but the restrioction is in the fittings anyway.



And that's how I came to modify the module. On my truck, the stock mnodule fitting is about . 24" inside diameter. This is followed by 2 more connections in the module of roughly the same inside diameter. So, to open it up, I have to scrap the stock parts and make something else work.



In all honesty, it's probably not a big issue in my application. But, it keeps me busy!



I'll post some pics in another thread so I don't stomp on yours!



Dave

 

[rweis]

CStewart is the guy with the module fittings. I got some from him about 01/2006. He does a lot of hunting way back in the back country so is gone for long periods of time.



I have not gotten to the fuel module fix yet, but the fittings are very nice.



Bob Weis

 

[Fishin Guide]

CStewart is the guy with the module fittings. I got some from him about 01/2006. He does a lot of hunting way back in the back country so is gone for long periods of time.



I have not gotten to the fuel module fix yet, but the fittings are very nice.



Bob Weis

Thanks Bob! I'll send him a PM.



I came across a guy that has a AN elbow with a pickup tube attached. It's just shy of 1/2" and will be an easy mod for my use. I'll try to post some info as I get it.



Now I just have to figure out how to attache my filter and I'm set! I think I am going to bury the filter in the tank. For the number of times that the prefilter needs attention, I will just drop the tank. It's easy enough to do.



Dave

 

[rweis]

The fittings are CNC aluminum made to fit the top grommet. Then they are 1/4 NPT and you can do what ever you want. He did a thing about using 3/8 brake line. He has a pretty decent thread about how he did what he did.



I have my return lines back to the tank vent tube (to use the entire tank for heat dissipation and mixing) so I am going to do both tank fittings as fuel feed. One to go to the RASP and one to go to the backup lp on the Hobbs switch. That way each fuel feeder will have its own lines and no check valves except where they come together.



I mount my RACOR fuel filter on one side of a 1/4 steel plate in the drivers side bed pocket. The RACOR 802 oil bypass filter is mounted on the other side.



Bob Weis

 

[Loghead]

Holeshot,

Did you have any trouble with your reworked setup hitting the underside of the bed?

It doesn't look that way from the picture of the installed unit, but I'm wondering if you had to do any adjusting when you reinstalled the fuel tank (turn the sending unit a few degrees) to allow enough room.

I repaired my sending unit using one of those expanding rubber plugs from the hardware store. It looks like it'll work, but the return line (or the hose clamp on the return line) is hitting the crossmember on the bed. The new setup is alot more flexible than the old one, so I just twisted the line a little bit and continued re-installing the tank. I'm crossing my fingers, hoping it works for a few years.



If the thing actually works out for at least a few months, I'll sketch it out with AutoCad and post it here. Proof's in the puddin' though.