Intermittent fuel leak?

[eetrh]

Hi all

I had the petrol tank replaced by the MOT station last year, the old one was rusted. Bought a new one from GSF. I think the petrol pump sounds slightly more buzzy than before the work was done, but you know how it is, you hear things when you know something has changed... Car is 89 325 saloon, standard, generally runs well (at maybe 22-28mpg on b roads & motorways)

Last week, I drove 150 miles twice. The first time used 45 quid of petrol, the 2nd time 20 quid. Both times, the dash guage read 30mpg most of the time (bit optimistic...), and the OBC gave reasonable figures too (but I don't know when the mpg was last reset, before the first trip).

From time to time, I notice a slight petrol smell, esp when engine is cold, but as the mpg hasn't changed much generally over the years, I put this down to the cold running enrichment (I don't use the car often, few k miles per year)

I've checked for leaks, but not found any - hence, perhaps it's an intermittent problem. My bro borrowed the car and thinks it was worse with a full tank, so maybe a filler problem or similar...

Does anyone have any ideas of where to check for leaks - common problem areas - before I have to pay to have it looked at, which I find rather awkward on an intermittent problem...

Any advice gratefully received!

Tony

[MrDazzle]

Where the two 150 mile journeys on similar roads?

You certaily can't have leaked away 25 quid of petrol in 150 miles though, you'd be practically knocked out from the fumes if it was leaking that much! Not to mention the trail you'd leave behind.

Does the car smell of petrol? Even 1 or 2 drops leaking will be noticable.

[eetrh]

Where the two 150 mile journeys on similar roads?

You certaily can't have leaked away 25 quid of petrol in 150 miles though, you'd be practically knocked out from the fumes if it was leaking that much! Not to mention the trail you'd leave behind.

Does the car smell of petrol? Even 1 or 2 drops leaking will be noticable.

2 journeys were bristol to Gatwick and the return a week later.

It doesn't generally smell of petrol, when it's not running. It doesn't leave any fluids behind at all when parked, clean driveway after 2 years.

Am stumped! If it's burning the petrol, why, and why doesn't it show up on dash guage. If it's leaking, I think I'd be able to see the stains on the underbody, but it looks dry... Am confused!

Does anyone know how it can burn 2* fuel compared to normall without going much faster (petrol roughly equalling power...)

Ta

Tony

[MrDazzle]

You'd burn more fuel if the engine wasn't running right...might be worth checking the spark plugs.

Might be a stupid Q, but are you sure it's using the fuel you think it is? I.e. you've brimmed the tank both times, you're not relying on the gauge?

[eetrh]

You'd burn more fuel if the engine wasn't running right...might be worth checking the spark plugs.

Might be a stupid Q, but are you sure it's using the fuel you think it is? I.e. you've brimmed the tank both times, you're not relying on the gauge?

Brimmed it twice. Thought at first gauge was faulty, but the refill proved it was right!

Haven't checked plugs, but can do. Will try to check other things like dizzy cap too... but it's a very sudden, massive drop in mpg. And I suspect these problems would show up in the fuel economy on the mpg gauge too??

Tony

[MrDazzle]

Maybe someone's been borrowing the car without permission...;)

[daimlerman]

Be worth checking the filler pipe,this runs from the flap where you fill the tank down to the tank proper.There is also a rubber pipe connecting this part to the tank.The filler pipe is known to fail.

[eetrh]

Be worth checking the filler pipe,this runs from the flap where you fill the tank down to the tank proper.There is also a rubber pipe connecting this part to the tank.The filler pipe is known to fail.

Cheers

This is what I need to know, what bits normally give trouble - otherwise, I don't know where to start!

Ta

Tony

[daimlerman]

Please do not use your lighter to look for leaks...

[DaveD]

the other bits that leak intermittently are the rubber fuel pipes to the fpr (Next to the inlet manifold) ..they crack and let a bit of juice out on start-up etc...only a couple of quid to replace and a VERY common fault

[eetrh]

Thanks DaveD, another thing for me to check...

[MrDazzle]

I used to have a fuel leak on my iS...not enough to cause noticable level drops, just a smell. Eventually I sorted it after replacing:

- Fuel Filter
- Fuel Filter hoses
- Fuel tank
- All the various gaskets on the tank
- Filler hose
- The small hoses (about 50mm long) that go onto the injector rail.
- Injector o-rings.

So basically almost the entire fuel system!

[eetrh]

I used to have a fuel leak on my iS...not enough to cause noticable level drops, just a smell. Eventually I sorted it after replacing:

- Fuel Filter
- Fuel Filter hoses
- Fuel tank
- All the various gaskets on the tank
- Filler hose
- The small hoses (about 50mm long) that go onto the injector rail.
- Injector o-rings.

So basically almost the entire fuel system!

Yikes. I hope I don't have to do that... I hate working with petrol, seems to get everywhere when you spill it...

I know the garage that replaced the tank had to replace some rubber bits, but it was all at the back. I'm guessing something else has aged and moved, and now leaks, but I can't be sure. Am also surprised I can't smell the petrol leak all the time, but it really doesn't generally smell!

Cheers for the advice guys

Tony

[MrDazzle]

To be fair, the tank needed doing anyway...it collapsed on a forecourt and dumped 40 litres of petrol. I wasn't very popular with BP that day!

It's good practice to replace the filter, so that doesn't really count either.