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Eviljohn

Hey polo people. 

Aa above, had an issue today with fuel return line leaking where it's connected to the fuel tank. I have plastic fuel hose along the bottom of the car with a little braided hose at the end to connect it to the tank. The braided was too far gone and started leaking. Day after i filled the tank! 

I have already put a weber on and the return is disconnected anyway. Had this set up for just over 2 years with no issues so far. 

As the fuel return outlet is easier to get to, can i plug the current fuel send and connect the new fuel hose to what is currently the fuel return?

Thanks for stopping by and any guidance you're able to give. 

Keep safe.

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Checked it all over. Can't find any signs of a leak on the tank, that is solid.  I think, i may have missed the outlet on top of the gauge sender end of the breather and overtightened the clamp.

Well i cheated a little bit. Had a bbq the other night, invited a couple mates, (in my social bubble,) when they rocked up, the car was already jacked up, rear wheel off. They asked what was going on,

steveo3002

cant you just fit a few inches of new fuel hose ?   theyre different diameter iirc 

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Eviljohn

Thanks for getting back to me. The outlets being different diameters is why i wanted to know if i can change them over, so I can get the right size fuel hose. 

Unfortunately, i don't have the right size to fit either one kickin around my shed so i need to get more hose anyway. I don't have the correct hose clips either. All mine are way too small. The ones i took off are crap too. They have normal crosshead screws that have been rounded out. Had to use pliers to get them off. So new clips for sure. 

My current plan, if it's possible, is to blank off the top outlet and use the bottom one as it's easier to get to if i have any future issues. So i'll have one length of hose running from the fuel tank to the fuel filter instead of small section of rubber hose into plastic pipe, into another small section of rubber which goes onto the fuel filter. 

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Eviljohn

So i measured up the outlets, got the correct size fuel hose and clips. Decided not to run it the full length of the car but i did blank off the fuel send and connect the hose to what was the fuel return. Filled the tank back up, no leaks, fired it up. Went fine until it ran out of whatever was still in the pipes but now there is no fuel going into the engine. Filter is bone dry. I don't have any kinks in the fuel lines i've added. 

Have i messed up my fuel tank by blanking off the fuel send outlet, (upper one,) and changing to the fuel return? Fuel seemed to flow out of the return pretty freely when i took the leaky hose off. 

The fuel tank is for the breadvan without injection.

The fuel return had already been blanked off when i had my weber fitted so apart from switching the outlets over, there wasn't really any change in set up i had.

Thanks for stopping by. Feel free to shake your head in disappointment if that's the case but if you can give any guidance at all, i'd really appreciate it. 

Keep safe all.

 

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Eviljohn

So i just found this which i could have really done with the other day. My bad for not searching properly. Turns out i can't use the fuel return as the fuel send as the pipes inside won't allow it. Dang it! 

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  • 1 month later...
Eviljohn

Hi all. Hope you're safe and well. 

I've managed get my fuel tank sorted but i now have an issue with the fuel gauge sender unit in the top of the tank. I've refitted it a couple of times now with the new O ring, nice and tight, but still get fuel fumes inside the car. Today i lifted the seat and found a very small pool of petrol under the seat, towards the back of the car. No sign of leakage anywhere else around the unit. 

Is there a knack to fitting this so it doesn't leak, and can i put anything on the Oring to make a better seal? I have hylomar blue and red to hand, also copper gasket goop. 

I did take a picture before i took the unit off to make sure it went back in the same way as it came out.

Thank you for any guidance you can give. 

Keep safe.

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steveo3002

is the vent hose on the top of the tank fitted /tight 

 

shouldnt need sealant on an o ring 

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Eviljohn

Both breathers are on tight at both ends. It's come from the fuel gauge sender unit for sure. 

I found a spot on the foam underneath the seat where some fuel seems to have soaked into the foam. I've whipped the seat base out, given it a clean and popped it in a sunny spot to dry/evaporate. 

I've taken the sender unit off again and made sure it's on properly. Again. See how that goes.

Thanks for reply, if you say it doesn't need sealant, i must have not put it back properly. 

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steveo3002

are you knocking the sender around with a hammer /drift ?...needs more than hand tight

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Eviljohn

No i used a pair of needle nose pliers to get a better grip on it at first. But as it was just one set, it was probly uneven distribution of effort. When i had another go yesterday, i used two flat head screwdrivers and pushed as far as i could. I haven't taken it for a run yet today to check it out. Will leave the seat base off when i do so i can check properly.

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steveo3002

with hindsight you would have marked where 12 oclock sat and made sure you whacked it around to match on the new tank

 

pretty it needs a whack...use a block of wood and tap it a bit , it tightens onto a taper 

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Eviljohn

Okay cool. I'll give that a crack. Thank you very much. 

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  • 2 weeks later...
Eviljohn

Hi folks. Hope you're all well. 

So far so good with this setup. I took a mallet and some things that fitted the grooves on the fuel gauge sender and knocked it round as far as it would go. Still having issues with fuel fumes inside the car. I got under it yesterday and the fuel return outlet that i have currently blocked off, has evidence of minor leakage. The bolt i have in the small section of hose has fuel on it. Doesn't seem to be dripping that i can find but still, not good.

The way i see it, i currently have 2 options. 

1. Make a better blanking section of hose, if anyone has a fit and forget way of doing this, feel free to step in.

2. Reconnect the fuel return. 

I switched out the stock carb for a weber about 2.5 years ago. The guys that did it just blanked off the fuel return in the engine bay with a snug bolt and hose clip. 

Would reconnecting the fuel return make any difference at all in how the car runs?

I did have the same setup on my old polo, but that still had the fuel return. Apart from a slight flatspot in the lower revs that i never got to the bottom of, that one actually ran a little smoother than this one. Especially at the higher revs.

Thanks in advance for any guidance you can share on this. Very much appreciated. Keep safe.

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dvderlm

Are you using the 5.6mm return line to feed the carb and blanked the 7.9mm feed line?

 

That might reduce flow and give some starvation at very high sustained load as fuel in the well drops and is not replenished fast enough, but the needle valve is 1.5mm diameter and under 0.25 bar pressure from the pump so that seems unlikely.

 

A swirl pot acts as an extra reservoir and return helps cool fuel in hot weather and it also can remove bubbles, yet a carb fuel well loses bubbles too.

 

If this is same carb and jets on same (or very similar) engine and exhaust and not worn out carb (500,000 miles on the million mile Saab) and no wobbly mount gasket or vac leak at any tubes or fuel tank rusty dirt passed inline filter,  strong pump and with good condition ignition then I'd be surprised it feels different due to pipes to carburettor.

 

No, I suspect the 5% Ethanol in modern fuel is a noticeable weakening compared to 2 years ago. An injection car can compensate. Carb might need 2 to3% larger idle and/or main jet or 5% smaller air corrector depending where its mixture was already marginally lean. Try pulling the choke gently partially on experimentally. Does that feel smoother with no blue smoke?  

Edited by dvderlm
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dvderlm

At the tank, how about using a blanking cap of correct diameter and a proper fuel clip, not a bolt in a hose which could wobble around and split. 

 

Though blanked in engine bay should be fine if the end of hose is higher than the tank.

Edited by dvderlm
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dvderlm

To find a fuel leak / smell I shook flour on the filler pipe which revealed a pinhole.

 

Have you checked all the breather hoses are attached?

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Eviljohn

Breathers are attached. Nice and snug. I think it could either be where i haven't got a good enough seal where i've blocked the fuel return line or i still haven't got the sender unit on tight enough. 

I managed to find the instructions that came with the Weber i have fitted. One of the steps is to reconnect the fuel return. The garage that fitted the carb for me didn't reconnect it despite having the instructions and having the car for about 6 weeks! Instructions say to use a T-piece with a restrictor in it, (the restrictor on the line leading back to the tank.) So i have got one of those, just need to get some more fuel hose and clips and i'll get that plumbed back in. I will be double checking all the fuel lines either before or when i do that. Didn't seem so bad last few days.

I will in the meantime try the flour option. Thanks for that. 

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Eviljohn

I have all the parts either ready or on the way to reconnect the fuel return line. Once i have reconnected it, will it affect the engine running at all or can i just fit it and crack on with the next job?

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  • 2 weeks later...
Eviljohn

All plumbed in. Running much smoother so far. Fuel smell in cabin isn't completely gone yet but is only faint now.

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dvderlm

Good work. A return line will keep the fuel cooler and be less likely for pump to push fuel past the almost closed needle valve, it will prefer to flow the path of least resistance.

But I'm still surprised it is noticeable.

 

A carb wants high flow, low pressure.

 

If it was the fuel tank sender seal I suppose it might have sloshed into the rear seat foam, which would evaporate.

Edited by dvderlm
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Eviljohn
Posted (edited)

It's definitely smoother. Not that is was super rough before. Want to see how it does on motorway. Hoping to get chance to do that tomorrow. 

There was definitely a fuel smell today. I did have a small puddle of fuel under rear seat after fitting new fuel tank, did have a small amount soak into rear seat base foam, happened to be one of those hot spells so i just took it out and left it in the sun to evaporate. Also made sure the sender gauge was properly tight.

When i was in the engine bay fitting return line the other day, tank was drained but the carb smelled heavily of fuel. More than i remember it previously. No signs of any obvious leaks though.

Only thing left is to recheck both ends of the breather hose for snugness. 

Thanks dudes.

Edited by Eviljohn
Wrong information entered.
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Eviljohn

Definitely got a leak! Went out today to find drips coming from the bottom of the driver side where the jacking point is. Jacked it up, drip stopped, checked filler neck, nothing i could feel on the way vertical section. Felt a little moisture under the bottom, horizontal section. Both hoses are on tight and fine. No other evidence of leakage anywhere on underside of tank. Except fuel had collected from wherever the leak is while i had it jacked up, when i let it back down, had a little trickle. Tank is about halfway full according to fuel gauge. 

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c.w.pritchard

Take the back seat driver side “door” card out and you should find pipe work. Check that.

Edited by c.w.pritchard
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Eviljohn

Would that be the breather pipe? 

I checked the small yellow, upper one, that seems fine. I know the end under the back seat is fine, i can feel what i think is the other end on the breather outlet on the filler neck but couldn't actually see it. If it's come off, would fuel leak out of there if it's filled about half way? 

Also, it had been about 14 hours since i had driven it. When i noticed the leak, there was a puddle about 30cm across which could have been fuel or fuel mixed with rain water. I put an old measuring jug under it, after about an hour, had around 200ml in it. Wasn't clear though. Smelled of fuel but not as strong as when i've drained the tank and it was opaque. Because of the amount that was in the jug, i put my, (cleaned,) oil drain pan under the car. Checked it when i got back, after about 7 hours, and there's just a very small puddle in it. Next chance i get to investigate will probly be Wednesday. Will report back then.

Thank you for that tip.

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Eviljohn

Very confused today. No sign of leakage at all. If i hadn't seen it yesterday, i wouldn't have known about it. Not even the usual fuel smell inside the car today. Was going to walk but took a chance a drove in to work this morning. Drive went fine. Checked the car couple hours later, absolutely fine. Bone dry where the drip was yesterday. Filler neck, fuel tank downpipe, ground underneath, all clear. 

 

Inside the rear "door" panel, is it pretty much hollow? When i take that off tomorrow, can i expect to find the larger breather pipe where it comes through the rear arch? 

 

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