Siphon stale fuel?

[timski]

Hi there,

My van has been off the road for several months and it won't run on petrol. Gas is fine. I think its because the fuel is stale. Is it possible to siphon the fuel out of the tank.

I saw this clip on youtube and thought this might work?

https://youtu.be/L7xu0zfSYUA

What do you think?

Thanks,
Tim.

[ghost123uk]

I very much doubt that fuel that is only a few months stale would prevent it running.
Suggest you put some fresh fuel into a plastic bottle, take off the pipe that is the input of the fuel pump, fit a temporary pipe onto the stub and into the bottle. Start on gas, then switch over to petrol. If it runs then, perhaps there is a fuel, or fuel feed (from the tank) problem. If it doesn’t run off the fresh fuel in the pop bottle, you have a pump or carb issue. Take care not to set anything on fire with the petrol in the bottle (goes without saying, I know, but you have to say it don't you )

[shepster]

Fuel pump more than likely.

[ethelred the ready]

Yes, worth checking petrol pump. Start on gas, place pipe from petrol cut off solenoid to carb in bottle, and either manually switch solenoid (mine has a manual switch over lever) or give it 12v petrol should pump into bottle whilst engine running. If not, or if flow slow dodgy pump or pump rod. Just had this on my LPG caravelle.

[timski]

Yes I guess you're probably right. I should do the check you said to see if any fuel comes out.

Nevertheless, the fuel is probably well over 3 months old as I only ever start on petrol. So I'd like to drain or siphon off the old fuel too. So still interested to know if you can siphon these old vans. I know it's not possible on new vehicles without a special siphon tool.

I thought if I can use the method in the youtube clip it'd be easier than trying to loosen the hose pipes.... especially in this cold weather. Could damage the hoses too.

Thanks,
Tim.

[ghost123uk]

If you really must, just disconnect the petrol pipe from the carb, run the engine on gas with the petrol override tap turned on, and collect the petrol that comes out of the pipe in a can. Simples

[300CE]

How much fuel is in the tank - would it be worth just getting some fresh fuel into a fuel can and topping up?

[Oldiebut goodie]

From BP:

Petrol
Petrol is a mixture of many components with different properties that contribute to the performance of the fuel. When
petrol is kept in an open container where it is exposed to the air, it will - in time - completely evaporate. As it evaporates,
the composition and properties will change because different components evaporate at different rates. This is a normal
feature of petrol and helps describe the process which takes place when it is stored in equipment fuel tanks.
Petrol in sealed containers
The storage life of petrol is one year when stored under shelter in a sealed container. Once a seal is broken the fuel has a
storage life of six months at 20°C or three months at 30°C.
Petrol in equipment tanks
The storage life of petrol in equipment fuel tanks is one month. This can be extended by topping up with one third of
fresh fuel, which restores the volatile components that have evaporated.
Topping up with fresh fuel will help, however it is not a foolproof strategy for engines that are used only intermittently.
The following principles may also help:
> Keep the tank half full to stop water vapour from being sucked in and condensing.
> Consider using a fuel that contains anti-oxidants, metal deactivators and corrosion inhibitors to protect metal surfaces;
such as BP Ultimate.
> Use a hotter spark plug to help to reduce carbon deposits.


Example of how petrol changes when stored in a fuel tank
Property Week 1 Week 2 Week 3 Week 4 Week 5
% volume lost 3 5 8 10 15
Octane RON 98.1 98.4 98.6 99 99.5
Density kg/l 15°C 0.75 0.76 0.765 0.78 0.79
Equivalent air fuel ratio at constant volume 13:1 12.8:1 12.7:1 12.5:1 12.3 :1
At the end of five weeks the fuel is 5% heavier and the fuel air mix will contain more fuel. This means your engine will
run richer possibly resulting in fouled spark plugs and higher fuel consumption.

[Jawin89]

Interesting, the gain in density through evaporation over the 5 weeks is 0.04, if it gained the same again it would have the equivalent density of Diesel.

[timski]

So quick update. I siphoned off the old fuel as I wanted to do that anyway and also just to discount the possibility of stale fuel being the problem. It would have been cheapest solution so no harm trying. The method I posted a YouTube clip of in the original post didn't work incidentally. There is some kind of restriction towards the end of the filler neck. I could get a tube past but it with a bit of a wiggle but it restricted my ability to blow air into the tank. In the end, I bought a £5 siphon from eBay and it worked a treat. It didn't solve the problem of the van not running on petrol though.

So I had the pump pressure tested as suggested and the mechanic confirmed the fuel pump is working fine (delivering correct pressure and consistently) but the injectors aren't working. I had a chat with Mick from VW Elite as I'm taking it there to have the LPG serviced and he said it could be that when the ECU wiring loom was fitted the leads to the injectors were not connected in the same sequence. That wouldn't be a problem if the van runs only on fuel but can cause the switch over to malfunction. Apparently these days Gasure and Elite modify the wiring of the injectors with a relay (or something along those line) to avoid this issue. Mick will do the wiring mod when he does the LPG service... unless it is some other issue that is causing the problem. Perhaps the wiring loom itself or the ECU? Anyway, hopefully Mick will get it sorted.

Cheers,
Tim.

[ghost123uk]

I've only just noticed Tim's van is an injection one
Andrew will sort it = top bloke

[ajsimmo]

So I had the pump pressure tested as suggested and the mechanic confirmed the fuel pump is working fine (delivering correct pressure and consistently) but the injectors aren't working.

I had a chat with Mick from VW Elite as I'm taking it there to have the LPG serviced and he said it could be that when the ECU wiring loom was fitted the leads to the injectors were not connected in the same sequence. That wouldn't be a problem if the van runs only on fuel but can cause the switch over to malfunction.

Apparently these days Gasure and Elite modify the wiring of the injectors with a relay (or something along those line) to avoid this issue. Mick will do the wiring mod when he does the LPG service... unless it is some other issue that is causing the problem. Perhaps the wiring loom itself or the ECU? Anyway, hopefully Mick will get it sorted.

I'm not sure what this means, but it's incorrect. Gasure used to fit an injector piggyback loom and emulator box - complicated, expensive and unnecessary on a Digijet as the ecu doesn't need emulation as it's a bit dumb. All that's needed is to switch off the 12v supply to the injectors when changing over to LPG, which I do with a delay timer (to smooth changeover) relay in the relay box above the coil. I believe Gasure may have now adopted the the same method.

Andrew will sort it = top bloke

Thanks John, but if you mean me, it's not coming to The Campershack.

Btw, Neither myself nor Elite (or any other outside contractor, AFAIK) work on behalf of Gasure any longer.

[ghost123uk]

Andrew will sort it = top bloke

Thanks John, but if you mean me, it's not coming to The Campershack.

Ooops, note to self = RTFM

[what2do]

How long have elite being doing LPG conversions? Shudder at the thought.

[what2do]

Andrew will sort it = top bloke

Thanks John, but if you mean me, it's not coming to The Campershack.

Ooops, note to self = RTFM

RTFM??? You're so down with the kids John! What's RTFM?