Gas tank not hissing!

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HayleyD
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Gas tank not hissing!

Post by HayleyD »

First post on the site, been readin loads of posts and have already cured quite a few niggles with the excellent advice on here.

However, my car dies when the fuel gauge drops below a quarter tank. It then requires TWO tetra cans (10 litres) of petrol before it will fire up again. Also, the fuel filler cap has never to my knowledge "hissed" when I remove it to fill up! Does this mean I have a leak somewhere? Where is the most likely place to find it?

I apologise in advance if someone has already answered this but I cant find specifically what I'm after.

Thanks in advance,
Hayley.
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nickrowe_2k
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Re: Gas tank not hissing!

Post by nickrowe_2k »

The best way to check if you have a leak is next time you fill your car up try and do it in the evening. If you wake up in the morning, move the car and theres oil everywhere you have a leak lol.

Another type of leak is when your driving get a mate to drive behind you and see if your spitting petrol from your exhaust as your driving.

Then just bang it into your mechanic :)

Not sure why your getting a hiss on the fuel filler cap, it may just be the seal. A hiss happens on the off chance on most cars its nothing that you should worry about :)
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Re: Gas tank not hissing!

Post by andyroo »

Hi Hayley and welcome to the club. :th:
Sounds like you may have picked up some dirty fuel in your system,you would know if you had a fuel leak.I would get your filter and injectors checked first.
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HayleyD
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Re: Gas tank not hissing!

Post by HayleyD »

Sorry, I should have been more specific, there is no petrol leaking. I meant perhaps i have a vacuum leak. Isn't the entire fuel system supposed to be pressurised? Hence the hiss you should normally get when opening the filler cap???

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Re: Gas tank not hissing!

Post by FGRob »

That's a different colour 2, brought it like that or did you have it done yourself.

It sounds like you could have a fuel pump problem, the pump is fitted inside the tank and the system is a pressurised one, if you are getting no hiss then it would suggest it's not maintaining pressure, also the pump is submerged which would explain the 10 litre fill up before it works again.

The tank is positoned under the back of the car just before the engine, not a nice job but it is something that can be tackled at home providing you are able to handle the spanners - if not then its your local garage.

You could always do a quick basic check by letting the car stand for 10 mins then pulling the fuel pipe of the fuel rail to see if the pressure is still there - it normally sprays fuel around, so be prepared to catch it, this will confirm that you have a pump problem of some kind.

That's providing it's not leaking of course :blush:

Oh yes and welcome to the club.

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Re: Gas tank not hissing!

Post by dawesy »

not sure on the hissing part, could be a faulty filler cap :confused1:
it could also be that the level sensor is goosed and sticking hence its actually running out of fuel but reading just under 1/4 tank.
when it dies is it instantly quitting or does it die as if out of petrol (kangaroos and peters out).
would be worth dropping the tank and inspecting the pump/ level sensor assembly.
nice looking 2 BTW like the colour :th:
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Re: Gas tank not hissing!

Post by Kinsy »

Sounds like your tank sensor is broken, needs re-calibrating, or the needle position is set incorrectly - do you have aftermarket decals over the dials (pink I'm guessing?). Does it register as full when you fill the tank? Make a note of how much it costs to fill up from totally empty, next time you fill up spend 3/4 the money - if the needle registers max you know it's just the needle set wrong.

Hissing shouldn't actually happen when removing the filler cap - it does on some older cars as air pressure release valves become sticky/jammed shut. The fuel system is pressurised by the fuel pump along the fuel lines only - it doesn't put the fuel tank under pressure!
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Re: Gas tank not hissing!

Post by peteV6R5 »

Kinsy wrote:Sounds like your tank sensor is broken, needs re-calibrating, or the needle position is set incorrectly - do you have aftermarket decals over the dials (pink I'm guessing?). Does it register as full when you fill the tank? Make a note of how much it costs to fill up from totally empty, next time you fill up spend 3/4 the money - if the needle registers max you know it's just the needle set wrong.

Hissing shouldn't actually happen when removing the filler cap - it does on some older cars as air pressure release valves become sticky/jammed shut. The fuel system is pressurised by the fuel pump along the fuel lines only - it doesn't put the fuel tank under pressure!
+1 with kinsy here.
The only real way to test the fuel pump is with fuel line presure gauge. This will tell youif the pump is maintaining pressure all the way up the delivery curve.
But still think that your sender is FUBAR or your fuel level dial is / has been messed about with and not set correctly and you are running short of fuel.

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Re: Gas tank not hissing!

Post by vinp182 »

Are you from the west mids by any chance?

Someone told me they saw a pink 2 the other day :)
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Re: Gas tank not hissing!

Post by Wabbitkilla »

Golly what a colour :shocked:

Ok, fuel tank isn't pressurised, but it has a vaccuum feed from the charcoal cannister.
Looking in the engine bay you will see the cannister as a black plastic box to the right of the engine. There is a pip that goes from it to the bulkhead behind the driver - this goes into the fuel tank. Another pipe goes to a solid pipe that crosses the engine bay along the bulkhead above the negin under the bracing. It then has a soft pipe connecting to an electric valve attached to the intake pipe. This valve then connects to the intake side of the throttle body behind the engine via another soft pipe. The valve is setup so that it pulses under certain revs / conditions, basically the engine sucks throught the valvle and pipes. This sucks fuel vapour from the tank through the charcoal cannister ... it's all about emmissions. The valve can get stuck, or more likely the soft pipes can come lose or holed when people work in the engine bay.

The hiss you hear when opening the fuel cap is actually a release of the suction, and it generally gets louder the less fuel you have in the tank. (Volume x negative pressure is proportional to vacuum stored).

Ok now that's dealt with...

If your clocks have been tampered with it could simply be the fuel gauge needle is wrongly positioned. The fuel pumps are in general reliable, but you know ... they have moving parts and can go wrong. Fuel tanks is under the cubbies behind the seats, I think you would have to drop the tank off to get to the pump. Certainly could be dirty fuel, but again the only way to be certain is to drop the tank and take a look inside. The fuel filt is also built onto the pump!

Good luck with solving the mystery
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HayleyD
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Re: Gas tank not hissing!

Post by HayleyD »

I'm from Derry in Northern Ireland, bought the car all sprayed up from a girl in Wales, but had to pick it up from her other house in Alicante in Spain. So my boyfriend and my brother had the job of flying there and driving the 2200 miles home!

She told me the day I bought the car never to let the car go below a quarter tank as it will stop. The fuel gauge does appear to work....as in it goes up and down when I fill it and drive it. I could live with the faulty fuel gauge but having to put TWO tetra cans in to get her going again is what is confusing me. It's run out 3 times in the year I've had her, and every time, 1 can is insufficient to get her going again. This combined with the lack of a hiss is making me think there is a fuel pump problem or a vacuum leak. I will try what you suggested about pulling the pipe off.

The interior of the car is completely stock, I asked the girl I bought it from, only changes are the wheels, bodykit and respray. Dials have never been touched!

The only other ongoing problem is that the engine light has been on since I bought the car, which I ignored cuz the car felt and sounded 100%, no leaks and not overusing any fluids. Then 1 day it simply stopped and refused to start. A local mechanic plugged in a code reader and we got P1305, igniter fault. 1 new coil pack later and the car was 100% again, however the light came back on the following day with the same fault code, it was cleared....and was back again with a few hours.
The car was still driving perfectly so I ignored it. However, about a week ago I started it up and it sounded really rough, almost the sound you get from a car firing only on 3 cylinders. This rough engine noise was also accompanied by a noticeable drop in power. Checked the usual, cleaned the MAF to no avail. Then 1 day, filled the tank to the neck for a journey to Belfast and back and miraculously the car was back to 100% again. Drove 70 miles to Belfast, stopped at a traffic light.....rough engine back again. Is this fuel tank issue getting worse??? Is it a pure coincidence. I'm well confused!!!!

Thanks for all the advice !!!

P.S. The colour is Daihatsui Rose pink with Rainbow metal flake!
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Re: Gas tank not hissing!

Post by vanilla.coffee »

I had this once. Not on an MR2 but on a Peugeot.
The fuel tank had imploded - sucked itself in and distorted. The centre of the tank had lifted (where the fuel pick up sat and so either side of the tank had fuel but sat lower than the raised part distorted by the tank imploding.

This is where I would check first, the shape of the tank.
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