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'Deleting' multiple fuel filler pipes KZJ78

graysworld

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One job in the pipeline (excuse the pun) involves removing the fuel tank. I have never seen a set up like it. Multiple pipes going to and fro the tank from the filler neck. I am used to the main filler and a single breather pipe. My question therefore is can I 'delete' the other pipes and have a simple filler and breather combination. Why are there so many pipes?

Graeme
 

Iwan

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I think a proportion of the smaller pipes are involved in the prevention of the fuel being drawn back from the engine. A lot of the problems when this happens is that the vacume left from the fuel being removed from the tank draws back from the engine.

My kzj 71 in the avatar does this only when there's less than a 1/4 of a tank of fuel.. if it doesn't start on 1/2 a turn, time to bleed the fuel through..
 

graysworld

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But if there is a breather then there can be no vacuum? And diesel fuel systems send unused fuel back to the tank via a return pipe. If you car won't start when down to a 1/4 tank it would suggest the breater is blocked.
 

Iwan

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Yes indeed it is lol.. the filler cap is sealed so no air can enter the tank from there. One of the small pipes runs above the fuel tank and goes into the box section that sits under the floor of the body.

So it's there that the air can enter the tank and all the small pipes make sure that the fuel doesn't run into the box section mentioned above.

I guess to fit a filler cap that has a breather hole in it, but the filler top is close to the height of the top of the tank so you would probably have fuel coming out of it hence the reason for all the small pipe work.. :thumbup:
 

graysworld

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Ah thanks Iwan, If the pipes are salvagable I will leave alone. But I will probably just vent the fuel cap and block up the small pipes at the tank end. What an over engineered system!

Graeme
 

Iwan

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I think I will also vent the fuel cap too, sometimes after I do a long run I release the fuel cap and relieve the vacume! It's quicker than bleeding it in the morning! LOL :thumbup:
 
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qbartx

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Where to start... from factory there is no pipe going into the body or whatever Ivan means. Air into the tank is actually drawn through the filler cap, it's got a little spring in it to keep vacuum at certain level. You can delete the pipes, nothing bad happens, i do it all the time.
I think I will also vent the fuel cap too, sometimes after I do a long run I release the fuel cap and relieve the vacume! It's quicker than bleeding it in the morning! LOL :thumbup:
There should always be vacuum when you undo the cap, it's not a reason for your problems, fit one way valve on the supply line and see if it helps.
 
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