Vanishing Fuel

[sgoedvolk]

For about the last two months there has been a very prominent fuel smell when standing outside my EX. I can put $20 gas in the tank and within two days the tank is empty (without any driving). I've placed a long sheet of brown paper under there are no signs of leaks ... all I can imagine is a large hole at the top of the tank but that does not make sense either. I'll drop the tank on the weekend but was wondering if anyone else has had this happen or any suggestions.

Thanks!

Shane

 

[aldive]

That big of a leak, w/o any gas on the ground sounds to me like someone is stealing your gas.

 

[sgoedvolk]

For almost two months I though that too .... until I locked it in the garage!

 

[shamaal]

I would think that if yo left 19 gallons in an open container it wouldn't evaporate that quickly. Perhaps a moose with an uncontrollable urge to joyride with his polar bear friends?

Seriously petrol smells are not normal and are seldom good. A leaky injector 'o' ring on the fuel rail or a clogged carbon cannister/bad purge valve would be my first guess. Any work done recently on the car particularly on the engine top?

 

[sgoedvolk]

No work on the car recently .... $20 buys me about 5 gallons gas in Canada, but even that is a lot to evaporate.

 

[aldive]

Are you basing the thank being empty on the fuel gauge?

 

[sgoedvolk]

Yes. I put just over 1/4 in. Within ~2 days it's in the red with no driving ... not a gauge, sender or battery issue - tank would be overflowing by now if that were the case... I think?

 

[aldive]

So you really don't know if the tank is empty?

 

[rlcrafts]

Had a similar problem with my 91 sport, ended up being the fuel sending unit at the top of the tank had holes in it.

 

[BrooklynBay]

Did you check your oil, and antifreeze to see if there is any sign of gas? Did you hook up a fuel pressure gauge, and monitor the pressure after you shut it off to see if there is any leakage from the injectors into the engine?

 

[JStrider]

so uh... youve got a fire extinguisher rated to flammable chemicals in your truck right?

 

[sgoedvolk]

Did you check your oil, and antifreeze to see if there is any sign of gas? Did you hook up a fuel pressure gauge, and monitor the pressure after you shut it off to see if there is any leakage from the injectors into the engine?

Not yet. These are great ideas and easy to do ... I'll do this a little later today. If fuel was leaking into the engine from one (or more) injectors would this not make for difficult starts? My EX starts first time, no problems. Thanks!

 

[BrooklynBay]

It would probably feel like it's flooded, but then this is still a mystery.

 

[BrooklynBay]

Another idea is to add UV dye to the gas, and check everything after a couple of days.

 

[sgoedvolk]

Eventually found it! Just as rlcrafts quoted above. There was a hole in the feed fuel line just at the base of the fuel sender plate that mounts to the top of tank. Just big enough to spew out fuel at a high rate when the engine is running (fuel pump on) ... so in 32 degree snowy weather I pulled the tank and replaced the unit ... what a pain in the ass ... I guess partially due to the cold. $258 later the EX is once again running.

Thanks for all your help.

Regards,
Shane

 

[DeRocha]

Eventually found it! Just as rlcrafts quoted above. There was a hole in the feed fuel line just at the base of the fuel sender plate that mounts to the top of tank. Just big enough to spew out fuel at a high rate when the engine is running (fuel pump on) ... so in 32 degree snowy weather I pulled the tank and replaced the unit ... what a pain in the ass ... I guess partially due to the cold. $258 later the EX is once again running.

Thanks for all your help.

Regards,
Shane

It makes perfect sense to me a fuel pump sender line has rusted through as they are only zinc plated steel; As opposed to the stainless steel braided lines these lines connect too.

But what does NOT make sense to me is your original statement... You indicated you put 5 gal of fuel in the tank, locked it in a garage, and within 2 days the 5 gals was gone (without any sign of a leak)...IMO there is zero way for this to occur (especially without seeing fuel dripping). The fuel pump sender and related hose is on the very top of the tank and would only leak if the fuel line was pressurized (ie the fuel pump is running).. After a short period of time a non-running car with a leaky fuel sender line will de-pressurize and stop the leak... There is just no way for fuel to travel uphill in a siphon situation where the top line has holes in it..

That being said it is easy to have the fuel leak out of the senders holes while the engine is running and the lines under constant pressure of the fuel pump. The leaking fuel would be dissipated by the air stream passing under the vehicle. If the vehicle idled in one spot you'd being to see it puddling...

 

[sgoedvolk]

What I can deduce was happening is that I would put some gas in, check the level and drive home ... but I did not check what I had at home! The leak I found was spraying gas all over the inside of the left rear chassis so a lot of it was contained (and sprayed over) the vehicle. I guess most of it just evaporated. Finding the cause was a bummer as I did not want to just take the tank out for fun. I had the engiine running and with a bright light could just see the fine spay. I initially though it to be a fuel line but as I dropped the tank the feed line separated from the entry point to the tank and I could see what was going on.