Another fuel tank plumbing option

[nkemp]

Let me preface that I dislike the design of the DeLorean fuel pump, boot, cover & plumbing. If we don't have gas on the pump we may have water. Every time you service the tank or pump it is a PITA. We are recommended to not fill the tank so that it does not leak. Owners complain about gas fumes. Parts shrink, deteriorate with gas exposure or tear easily when gas soaked. There are lots of opportunity for leaks and problems. Other than that it is a pretty good design. Yes I've heard that some installations work well... but plenty don't. So much for the rant...

Here is the idea (works with any current pump or sump implementation):

• A through the wall, double barbed fitting for the return line installed on the tank top
  
  • Inside run the return line from the fitting to the sump of your choice
  • Outside connect to the return fuel line
• Hang the pump in the existing bracket inside the tank
  
  • Cut off 1-2" of the exiting boot to pad pump to reduce vibration
  • Keep pump low in the tank for additional immersion in the fuel to promote cooling and long pump life
  • Run the hose from the pump inlet to the pickup screen per the sump implementation.
• A through the wall double barbed fitting for the pressurized line installed on the top of the tank
  
  • Inside run a fuel line from the fitting to the pump outlet
  • Outside connect to the pressurized line.
• Use through the wall electrical connections for the pump on the top of the tank.
  
  • This could be run under the boot (yet to be discussed) but could be a point of leakage
  • Could be installed through the boot but why not install on the tank top?
  • There may be other options...
• Use a cover (flat top or slightly domed) that covers completely the fuel pump hole. Not like the current boot with mounting hole for pump and return line but one that is a cover, no holes and is secured with a hose clamp
  
  • This is where I came to an end ... I can't find a cover for the hole. Anyone have any ideas? I don't think a plug would work
    
    
    • OD of tank opening at fuel pump opening = about 111mm/4.37"
  • A fiberglass one could be molded pretty easy but likely requires some form of rubber gasket or O-ring
  • The pump is now totally in the tank per today's fuel pump installations
    
    • If the pump leaks a bit it is in the tank
  • There is no "pond" to collect any water and no fighting with the pump cover

In this design, servicing the tank/pump is a lot easier since the lines use through tank fittings and are not disturbed. The return line should never have to be serviced. The supply line can be removed from the pump if the pump is removed. Water cannot collect on the pump. Gas leaks are not a concern.

As indicated above I have been unable to find a boot to cap off the pump opening. I know that one could be molded using the existing boot material. I was hoping to find an off the shelf solution for capping off the tank.

Any thoughts, ideas or sources?

Nick

[Farrar]

How about a plastic peanut butter or mayonnaise jar lid to cover the hole? That'd probably be big enough.

Farrar

[nkemp]

It needs to be flexible enough to tighten down with a hose clamp. And the threads would likely leak if gas was splashed or filled up to the top.

[Farrar]

It needs to be flexible enough to tighten down with a hose clamp.

Why?

And the threads would likely leak if gas was splashed or filled up to the top.

That's what big O-rings are for.

Farrar

[LEVY]

Do you really believe he is serious?

It needs to be flexible enough to tighten down with a hose clamp. And the threads would likely leak if gas was splashed or filled up to the top.

[Bitsyncmaster]

I like your ideas.

I put the boot clamp on the pump boot so it holds tight, never leaks, can fill the tank right to the cap. Then I just use tywraps to hold the outer cover around the clamp. Have to make a small cut in it to clear the clamp worm gear.

I've also thought about making a sump in the tank so you could run it empty without intermittent stalling. But you would need a sump extending below the cover plate so not to safe.

[LEVY]

Hope you are not talking about Farrar ideas!

I like your ideas. .

I put the boot clamp on the pump boot so it holds tight, never leaks, can fill the tank right to the cap. Then I just use tywraps to hold the outer cover around the clamp. Have to make a small cut in it to clear the clamp worm gear.

I've also thought about making a sump in the tank so you could run it empty without intermittent stalling. But you would need a sump extending below the cover plate so not to safe.

[nkemp]

I like the GM pump assembly/sumps. They use back-flow valves allowing the fuel in the sump to remain higher than the tank fuel level yet fuel can flow in from the tank or over the top depending on tank level. This helps keep the fuel pump cooler as well. It also has a built on fuel level sensor ... with the wrong configuration for the D

check out: http://www.gasgoo.com/auto-products/...3/1142527.html

That said, it does not get any lower than the flat bottom tanks we have.

I've heard that the original design would allow pumping the tank nearly dry. If one has a baffle then it is difficult to get all the gas out. If one has a sump arrangement, which the original was supposed to be, the return fuel keeps it full avoiding stalling on turns while pumping a long ways towards dry.

But the design is less than optimal. So I'm thinking the GM sump might be a nice addition.

[Farrar]

Do you really believe he is serious?

I will be the arbiter of my own seriousness, thanks very much whoever you happen to be.

If there's no need to remove the cover for the hole where the old fuel pump used to be, one could simply RTV a piece of plastic to it. I was under the impression that the original poster was seeking help. I offered some. But my ideas evidently suck since they're not high tech. Or I was mistaken in my assumption that the original poster was seeking help. Either way, AMF.

Farrar

[AdmiralSenn]

I think redesigning the pump and ports is a great idea. I'd be tempted to do this even though my (OEM style) fuel system is currently working great.

I think you're right in pinpointing the tank seal as the hardest part since it's likely to require a one-in-a-million crossover part or something custom.