Cars been eating alot of gas recently

[Yakozan]

My S15 has suddenly started to chew alot of gasoline lately.
Idle is fine and vacuum too. Doesn't feel like the car is much slower.
But I do smell alot of gasoline after I turn it off and mileage is horrible.
Latest fillup I made about 350km with 48L of fuel.
Now the meter stands about 2/3 full and I've only done 130km.
Used to be able to get about 70-80km before the neddle even moved before.
The also get little spluttering from the exhaust on lift-off.

Just wonder what I should check.

I've made a small list.

*Clean AFM wire
*Clean airfilter
*Check for boost leaks

Anything else?
Could it be exhaust related? Could have a small leak on the middle damper.

 

[Paddy]

But I do smell alot of gasoline after I turn it off.

Hmmm... you might want to check the top of the fuel pump aswell. you know the big black plastic screw on ring... might be loose, mine worked its way loose a few weeks after fitting a walbro...

also maybe get a look underneath and see if you've any fuel dribbling down the back of the tank.

i guess i was loosing about 2litres per tank of petrol that way

 

[Yakozan]

Hmmm... you might want to check the top of the fuel pump aswell. you know the big black plastic screw on ring... might be loose, mine worked its way loose a few weeks after fitting a walbro...

also maybe get a look underneath and see if you've any fuel dribbling down the back of the tank.

i guess i was loosing about 2litres per tank of petrol that way

It doesn't smell inside the car. I just smell it after I step outside. Haven't noticed any puddles or moisture under the car except from the AC.

 

[Paddy]

it wouldn't really leave any puddles, i've found it evapourates by the time it reaches the bottom of the tank.
Fuel feed would be one of the first things i'd check for... leaks, connectors, return pipe etc. my thinking would be that if you can smell fuel, its not where it should be...
is there any change in the exhaust, smoke etc? anything that would point to over fuelling?

 

[Nicely]

Most of the things you've suggested should make you notice a performance hit too. Fuel leak wouldn't.

Exhaust might make a small difference, but not that much.

 

[Yakozan]

OK. I'll check the lid and look for leaks.
There might be a small performance loss. I haven't noticed much though, but the weather has been changing alot recently so that may have masked it.

I'll get the car on stands and look around. need to bleed the brakes anyway.

 

[Nicely]

Well, look for all the obvious things you've said. Boost leak or dirty AFM. Maybe lambda...

 

[ichi-go]

Usually bad fuel consumption leads to o2 sensor

 

[Yakozan]

Usually bad fuel consumption leads to o2 sensor

how do I check that?
Unplug it and see if the car runs differently?
If it does the lambda work, if it doesn't it's broken?

Checked for ECU fault codes a couple of days ago with my greddy informometer. 0 codes.

 

[Yakozan]

Was at the garage tonight and was supposed to try some of the things.
But I was going to switch car but the battery was dead as it's been standing for quite some time now. So I spent most of the time looking for my battery charger.

Had a closer look on the plastic lid above the fuel pump. It was a little loose. When I removed the steel lid over the plastic one I could smell gasoline. I could also see a little moisture there. Could screw on the plastic lid about 1/4 turn.

I hope this solves the problem. Filled the car up. 20L for 140km. mostly highway.
Will fill the car up tomorrow night too and see if it gets better.

If the lambda was faulty. Wouldn't the ECU send an error code?
I can check for error codes with the greddy informometer. I can also check Air/fuel and O2. But I don't know what to look for so didn't bother.

 

[Nicely]

Did you check that none of the connectors were broken?

 

[Yakozan]

had a quick look at them and they looked fine.
I'll look closer this weekend. Just didn't have much time as the batteries was dead in all my other cars The Skyline battery was beyond saving.

 

[Nicely]

You've got to get that lid on really tight :nod: I used a hammer and screwdriver on the ridges.

 

[Yakozan]

You've got to get that lid on really tight :nod: I used a hammer and screwdriver on the ridges.

OK
Will the gasoline vapourize if it doesn't seal 100%?
Or maybe it leaks when cornering fast.
Could it really make that big a difference though?

 

[Nicely]

No, I wouldn't have thought so. Not from just being loose.

 

[sliding-r]

OK
Will the gasoline vapourize if it doesn't seal 100%?
Or maybe it leaks when cornering fast.
Could it really make that big a difference though?

ok, what was the verdict?

mine is having similar symptoms! and im running a walbro and it started since then, will get on and ahve a look in th morning

 

[Paddy]

im running a walbro and it started since then

I'd recommend checking the fuel pump cover, especially if you smell fuel. It may not be sealing the tank fully since the walbro was fitted. I think it will undo itself with time if it wasnt hammered into place as described above. When I tightened it up on my car I got better mileage :thumbs:...

 

[Jay]

tubby gasket? i just replaced mine along with a new manifold (thanks to craig for that one!) and its gone from shockingly bad mpg and smelling fuel to moderatly bad mpg and no fuel smell. i should aslo point out that the exhaust mani was badly cracked hence the change...

 

[LuPix_S15]

^^^ +1

If you can smell fumes/fuel when you pop the bonnet or even when driving then check tubby gaskets. Also use a large internal diameter vacuum hose and listen for 'blap blap blap blap' around the gasket area - I can detect a leak straight-away using this technique

 

[Nicely]

Mega thread revival. Come on Yako, let us know the outcome...