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Paul Coleman

Fuel tanks... again!

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Has anybody cut their fuel tanks open and had a look at the bowl in the bottom where the take off pipe is located? The reason I ask is that on mine one of the bowls had the take off pipe sticking up and the other tank (where the fuel pump connects) had the pipe flush with the bottom of the bowl. I can't decide if the bowl is there to act as a sediment trap (if the pipe sticks up) or just to be able to fully drain the tank (if the pipe is flush). Does anybody know the answer?

Thanks, Paul.


Lotus Esprit [meaning] a 1:1 scale Airfix kit with a propensity to catch fire

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Can't answer that but can say, the rhs tank (UK=Driver side) has the balance pipe a little way up the bowl, the bowl has a bafle in it, that I assume is to reduce flow between the 2 tanks when cornering.

I'd guess it's for draining purposes primarily, as most cars tanks could be removed without causing them to stop retaining fuel, but the balance pipe on ours means if you want to remove the tank you have no real option but to drain it, and draining via the balance pipe is not a good idea. You would end up with 2 jets of fuel coming from roughly the same place, btu going in opposite directions, needing 2 containers, which at some point need to go into one conatainer when the fuel level is so low that both jets join.

Andy

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Hi Andy

Unlike yours my S1 UK driver's side tank had the take off pipes almost flush with the bottom of the bowl and no baffle between the two pipes (crossover and fuel pump). However, my passenger side tank had the pipe sticking up the full depth of the bowl which seemed odd to me. I cut the pipe down to match the other side but on reflection maybe I should have left it and increased the other two? Having the pipes flush will mean that any crap in the tanks will make its way to either the fuel filter or possible clog the crossover pipe. Whereas with the pipes sticking up in the tank any sediment will collect in the bowl and stay there for good. I can't decide which is best but I'm leaning towards adding pipes on all three before I seal the tanks back up again. Decisions, decisions, decisions...

Cheers, Paul.


Lotus Esprit [meaning] a 1:1 scale Airfix kit with a propensity to catch fire

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Wouldn't changing the fuel filter be a lot easier and cheaper than having to empty the bowl of sediment when it inevitably fills up?

I know which job I'd rather do!


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I am sure that the standard for tanks has no stem riser into the tank - to prevent sediment build-up etc (yes, change that filter).

That said, there must be a specific reason for the stem in one tank only. I would say - that it could be due to differing heights of tank installation, therefore requiring a short stem to even out the heights. Maybe.

Iain

ps. Sorry Paul - this just made your refit more 'challenging' huh? heh heh heh :devil:

Edited by iainskea

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Wouldn't changing the fuel filter be a lot easier and cheaper than having to empty the bowl of sediment when it inevitably fills up?

I know which job I'd rather do!

Unless it's a rust trap? The inside of my tanks were pretty bad and any flakes of rust could clog the pipes if they were flush. I hopefully won't suffer from this once I've painted the inside of the tanks so having the pipes flush may be okay? As far as sediment and emptying tanks go I think the idea is that the bowls are big enough so that it never fills up during the life of the car.

Cheers, Paul.


Lotus Esprit [meaning] a 1:1 scale Airfix kit with a propensity to catch fire

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I think I have determined the answer to my own question... the nearside tank should have the pipe sticking up to prevent silt in the bottom of the tank clogging the crossover pipe (the flow in the crossover pipe is only one way when the pump is sucking fuel). The offside tank doesn't need a sediment trap becuase the fuel filter is fitted to this tank. This all means that I shouldn't have been so hasty in cutting the thing off in the first place.

This does lead me on to another fuel question though... when you fill the car up do you have to use both filler caps or is the crossover pipe big enough to balance out the fule into both tanks during filling?

Paul.


Lotus Esprit [meaning] a 1:1 scale Airfix kit with a propensity to catch fire

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The balance pipe is amazingly small. So the fuel balance process is not speedy. I usually end up filling on both sides then return to the original side I started with to top off. Tha last action is to address the inevitiable drop in fuel level as it races to the tank with less fuel while I move around the car.

Even with a bigger crossover pipe/hose the takeoffs are quite small. I know some folks have welded in new and larger takeoff taps while the tanks were out to facilitate the balance at fillup and while driving.

Dom G


Dom Giangrasso

1977 S1 Esprit - Lagoon Blue

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Hi Dom

Thanks for the reply. It confirmed what I though - that the pipe was too small to balance out that amount of fuel when filling from a pump.

I have left the original take off pipes in the tank but added small standoffs on all three to act as a silt trap.

Regards, Paul.


Lotus Esprit [meaning] a 1:1 scale Airfix kit with a propensity to catch fire

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