Draining a porsche 930 fuel tank

[derekuk930owner]

Hi everyone

Can anyone help me in how to drain a 930 fuel tank .I inadvertantly pumped diesal into my petrol tank and luckily enough realised.I then diluted the tank with 5o litres of petrol.The result is the engine runs lumpy and obviously doesnt run smoothly with thick white exhaust smoke out of tail pipe.

Ive used engine treatment and fuel injector cleaner.I need to know how to drain it .all my fuel bar a quarter tank is now gone according to the fuel gauge.

Can i simply just remove the fuel sender unit from the tank then syphon it off using that access point?

Many thanks

Derek

[tab tanner]

There should be a large (allen hex) drain plug in the bottom of the tank, the hex is a 17mm

[derekuk930owner]

so what that be under the front of the car ? sorry im new to all this so please have patience .Are there any cowling to remove and for those of you who have done it does it require lifting to fit under it ?

Many thanks

[willtel]

Originally Posted by derekuk930owner

so what that be under the front of the car ? sorry im new to all this so please have patience .Are there any cowling to remove and for those of you who have done it does it require lifting to fit under it ?

Many thanks

Yes, under the car. The trunk has a large hole in it that the fuel tank passes through, you can see the top of the tank from above and the bottom of the tank is accessed from below the car. There are several fittings at the back of the tank and the drain should be there.

It should be obvious once you get under it.

[HarryD]

Derek,

Welcome to the Best Porsche BBS.

The bung they are speaking about can be seen in this picture, right inhte middle.

[tevake]

You can get most of it out just siphoning thru the fill opening



I used an old outboard motor fuel hose. Used the built in pump to get the fuel flowing.
Should be able to find a hose with pump at auto supply store.
Or try your luck with a length of hose, don't swallow!!
Cheers Richard

[JP911]

Start by siphoning from the filler neck or from the sender opening (personally, I prefer the sender opening). You can then get any remaining fuel out though the drain on the bottom if you so desire. If you pull the plug on the bottom of the tank you're going to have a tsunami of fuel to catch.

Good luck!

[crustychief]

Diesel sure will clean up the internals of the engine though! I would just siphon it as mentioned. If you remove the plug that has been there for a number of years it may not seal up right.

[derekuk930owner]

Top job boys ! Thanks very much .This is the top site .Ive had the 930 for years now shes covered on the drive hardly ever gets driven.now ive turned 45 ive suddenly thought "hey get her up and driving sort it out get a project going".So here i am years after using the forums to rebuilt alternators and minor repairs .Who knows might look to rebuild the engine !


Noooo tooo scarrry ! Thanks gents i will try syphoning whats left of the remaining quarter tank via the filler then i can think about the hex nut underneath.The pics are mega helpfull thanks guys

[derekuk930owner]

just a thought ,does anyone jnow how much fuel is left approx in a quarter tank of a 3.3 930 gas tank?

Just need to work out suitable container size wise .

[bkreigsr]

21 x .25 = 5.25 gal

or on your side of the pond:
79.5 x .25 = 19.875 lit

Bill K

[willtel]

Another option would be to remove the fuel line from the CIS fuel head in the engine bay and use the fuel pumps to drain the tank. The fuel pumps can be forced to run manually by pressing on the metering plate inside the fuel head. That way you wouldn't have to jack up the car and deal with the drain plug.

You should check out the 930 forum and introduce yourself, there is some good turbo specific knowledge over there.
911 / 930 Turbo & Super Charging Forum - Pelican Parts Technical BBS

[derekuk930owner]

willtel

i have the fuel sender unit out and despite sucking on a pipe for dear life other than getting a mouth full of diesel gas mixture and burning my mouth off not much is happening.Is there a link anywhere as to how to do it step by step (diagrams for idiots ie me) via the fuel pump method?

mANY THANKS

[derekuk930owner]

MANY THANKS BK.....NOW I KNOW what size container !

[bkreigsr]

the discharge end of the drain hose must be lower than the container being drained at all times - since your tank is probably 4-5 inches above the ground, the container must be low and shallow.
lacking such a container, you can jack the car up to a decent height (both sides) and suck away.
Bill K

[derekuk930owner]

thanks bill k

im rather new to all this lol

[derekuk930owner]

now under the bonnet 17 mill hex nut ? lord where on earth do you get one of them from ?
im making hard work of this im sure .so far syphoning isnt working ,dont think i have a 17 mil hex .so my options ?

use the fuel pump as suggested by willtel but i dont know how to do that i need an idiots guide .
Or just a thought ,on the picture above of the underside of the petrol(gas )tank i see a black hose coming out of tank to a unit ? could i disconnect the hose and drain it that way ?

[bkreigsr]

that would work - be prepared for a major gush when disconnected - keep a fire extingusher handy - and no open flames for 3 kilos.

the 17 mil allen wrench is used on a bunch of vw/914 products and the 924-968 trans.
most parts stores sell the 17 allen socket by itself.

[JFairman]

Seems like getting the little fuel line off the back of the tank would be easier and better than removing the big plug that might not seal when put back on.

After that I'd remove the fuel supply line from the fuel head and run the rest out from there. Just turn off the pumps right away when it starts to run dry.

If you're gonna suck on hoses full of deisel and petrol to siphon more out, keep a cold Mackeson XXX or Guinnes Stout open nearby... It'll sooth the gasoline taste burning away in your mouth nicely.

[derekuk930owner]

boys ive given up on the sucking idea !
i cant access the pipe coming out of the rear of the bottom of the tank as it has a large shield blocking it and appears the 17 mil bolt holding it on is seized,cant accomplish one task without having to do 5 before it .

Only option now is to use the pumps to do the work for me as suggested earlier but i dont know how without a step by step idiots guide.its been one of those days