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Fuel tank vent thoughts.


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So now the Opel is back up and running! one issue i need to sort if fuel tank venting.

So im after some thoughts and advice from any of you injection experts out there!

My setup is this: In tank fuel pump, outlet and inlet go in the top of the pump and the original A inlet is blanked off. On the A they have two vent pipes at the top of the tank that on the original loop up and connect to a fitting on the filler neck, with one them then coming down with a tube that vents to the air at the back of the tank.

I have looped the two vents at the top of the tank together so that is effectively blanked off and then took the filler neck outlet down to the original vent to air location on the back of the tank and added a small motorbike breather fitting which is supposed to let air in/out to stop any build up. I don't know if the fuel filler cap is vented?

The issue i seem to have is that i get quite a bad fuel smell from the area of the vent and it seems worse if i have been doing a fair bit of cornering. I have checked and everything seems leak free and the filler hose is new. Im going to be doing some more investigating but thought while i was there it would be best to make sure i have the right setup.

Also if the car is just sat in the garage you do get quite a smell of fuel when you fist open the garage if its been a few days?

Again, no leaks that i can see.

I have attached the diagram from the manual of the original tank setup and the late A's in Germany had the injection so a pic of that setup and the breather fiting.

Any thoughts and help would be great.

Andy

opel-manta-a-series-injection-fuel-tank_Page_1.jpg

opel-manta-a-series-injection-fuel-tank_Page_2.jpg

51SZcIQj5IL._AC_SX679_.jpg

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if i understand correctly you have vented the lower pipes .where is the vent thou ? it needs to be at the highest point.otherwise on cornering fuel may find its way back into this pipe.on the 'b' setup the vent pipes all meet at the top of the filler neck but are actually vented by a pipe that then goes down and into the chassis. even thou it vents down there any fuel would have to enter the pipe right at the top of the filler neck which it couldnt do .(unless you totally brimmed the filler neck !)

this setup on yours may be compromised by blanking the two pipes(joining) and may be creating the issue, unless as suggested its a hose type problem.

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Posted (edited)

Number 1 in the attached is the two vets that i have joined, and 2 is the outlet im using for the vent so its as high up as it can be.

I will do some investigation on the pipe in case its not ethanol resistant.

All the other fuel lines are good ridge hard line with fittings so no rubber hoses so it has to either be the vent pipes of the filler neck pipe.

 

Andy

pipe.jpg

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if the original pipes that you have now joined need to come up to the filler neck and you have now stopped that happening that may be something to do with it. they wouldnt go to the trouble of putting them there in the first place otherwise. joining them has made them non existant right from the stubs.thay seem to design these breathers to account for all possibilities of driving,tilt,furl level,heat expansion etc so try bringing them up to the neck and joining them into the pipe there. 

worth a try ?

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31 minutes ago, cam.in.head said:

if the original pipes that you have now joined need to come up to the filler neck and you have now stopped that happening that may be something to do with it. they wouldnt go to the trouble of putting them there in the first place otherwise. joining them has made them non existant right from the stubs.thay seem to design these breathers to account for all possibilities of driving,tilt,furl level,heat expansion etc so try bringing them up to the neck and joining them into the pipe there. 

worth a try ?

Think i will get some other hose and then give your and @Jessopia74 thoughts a try. As you say there must be a reason but then i wondered why the setup was different when they went to injection? as they dont seem to have a breather but maybe they have some sort of pressure relief valve up on the injection side?

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4 hours ago, cam.in.head said:

as far as i know the breather system is still the same on injection ? 

its not a totally sealed / charcoal canister type on later mantas surely ? ?

Nope.

If you look at the second pic at the start of the post you will see the setup. Was only on the last few German A's as far as i know. Not see one in the UK with it on but did see a couple of German ones many years ago with it fitted.

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3 hours ago, cam.in.head said:

as usual ,im thinking 'b 'series . didnt realise a's had injection back then !sorry. 

Im sure its the same sort of setup.

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