85 Jaguar XJ6 siphon old gas out of tank

(JR) #1

Looking for some advice on removing the old gas out of my driver side tank with a siphon hose. Is there a siphon hose kit that I should purchase on Amazon that someone recommends? I would rather siphon then to pulll the plug for in fear of damaging the old tank. Your help would be greatly appreciated.

JR 85 Jaguar XJ6 III

(phillip keeter) #2

If you want to remove all of the gas from the tank, you will need to pull the plug. You should not be at much risk of damaging the tank by removing the plug. When you’re down there, you can remove, clean and/or replace the inlet tube filter within the tank.

(PeterCrespin) #3

If you knew for a fact it was purely old petrol, then fine. But since you’d want to get rid of any rust, and rust flakes are considerably heavier than fuel, siphoning is unlikely to drag the big flakes uphill a couple of feet . So you’'ll be left with junk in the bottom of the tank and no way to clean it out or service the filter, as Phillip said. Maybe siphon to get most of it out, then drain plug to manage the last half gallon. Filtered stale fuel is fine for flushing a cruddy tank several times before you go to clean fuel for the last wash.

Be safe…

(Paul M. Novak) #4

I have never had good luck with siphoning fuel at the filler caps in my Series III saloons. The filler cap flap and obstructions inside the tank seem to stifle any of my attempts to siphon any significant amount of fuel from the tanks.
If you are concerned about removing the large drain plug to drain the fuel then first try removing the smaller 9/16" set screw and sealing washer. It should come out more easily and allow fuel drainage. However drainage will likely be slow. If there is debris in the tank you might have to poke a small screwdriver in the opening to keep a path open for the fuel to drain between the drain plug and the in tank fuel filter sitting right above it.

Remember that each tank can hold 12 gallons of fuel and fuel transfer between the two tanks is possible if your changeover valve does not seal completely. So you will need a large container to hold all the fuel. Some Jag-Lovers members have posted about being surprised by how much fuel drained out, overfilled their container, and spilled onto the floor.

BTW I recently drained both fuel tanks in my 1984 XJ6 Vanden Plas to inspect their interior’s, clean out the debris in the bottom of the tanks, and replace the large rubber drain seals (they were cracked but not leaking yet). While the tanks were empty I removed and replaced the fuel filter in the spare tire well, removed and replaced the two in tank fuel strainers, removed and replaced the two aftermarket inline fuel filters that I installed, and removed and tested the two return valves and changeover valve for proper operation. The left return valve did not open and close crisply and it leaked vacuum when I tested it with my vacuum tester so I replaced it with a good one that came from one of my XJ6 parts cars. I hope that this preventative maintenance will improve my chances of having no fuel delivery issues when I complete the engine swap on this car later this month.


(David Jauch) #5

If you clamp all three fuel hoses (safer), add a long tube to the tank you want drained and then drain it in a container it will be somewhat easier. Then you can open the drain plugs and, as per the topic from which I quoted myself (you’ll find the list a few posts earlier), flush them with the fuel you collected into a container instead of having a lot of it running down your arm and onto the garage floor.
Siphoning per se is a pain as I had a hard time through the filler flap.
Another alternative is to connect to the fuel line somewhere and let the pump do the job until most of the fuel is out.

(Aristides Balanos) #6

There is also an other way, but only if the tank is full bellow 1/2.
Remove the rear light and then the fuel sender behind it.
You will have a big hole to put your siphon tube in and you will also be able to visually inspect the tank for rust and decide if it needs further attention.


(David Jauch) #7

…but don’t make the mistake I almost made when I thought (from the fuel gauge) that the tanks should be empty enough only to find out that about half full isn’t necessarily low enough. The plus side is that the plug can stay intact. With a large hose, you might even get a decent amount of crud out (I have drained aquariums with a hose and it can suck out anything), and then you can decide about the drain plug judging from what it looks like inside.

(Doug Dwyer) #8

Another option:

Remove inlet hose to the fuel rail
Remove fuel pump relay
Apply 12v to white/green wires at relay socket

You’re know letting the fuel pump do all the work.

Extending the fuel hose to easily reach a container will be needed but, otherwise, no fuss and very neat.

But I certainly agree that pulling the drain plugs is a good idea so more fuel can be removed the inlet filters can be replaced


(David Jauch) #9

But… I said it first!
All three filters (socks, filter) need to be changed anyways. If the fuel is really really bad one might risk locking the pump for good, as happened to me. However, you’re not doing anything different than when you run out of fuel, so that risk is very remote.

(Aristides Balanos) #10

Indeed !
But I said, if only the tank is bellow1/2… (:


(Aristides Balanos) #11

Has happened to me too…

(Paul M. Novak) #12

I have had the fuel pumps in my XJ6s and V12 Vanden Plas lock up on me a few times. That is why I added the inline fuel filters between the fuel tanks and the changeover valve several years ago. Since then I have not had any such fuel pump problems.

BTW, a few times that the fuel pump stopped I was able to free it up in place and get it running again by reversing the leads momentarily at the fuel pump, putting the transmission shifter in D or R, and turning the key to the Start position to get the pump running backwards. This temporarily reversed the fuel pump direction which freed up whatever debris had clogged it up. When I heard the pump running again I returned the fuel pump leads to their correct position, started the car, and drove home. It was on one of these successful episodes that I went home and added the inline fuel filters.


(JR) #13

Thanks Paul, what is the part number for in in line fuel filter you installed?

Thanks JR

(Paul M. Novak) #14

Attached is a picture of the inline fuel filters that I added to my three Series III saloons. I ordered them online but you should be able to pick up similar ones at any auto parts store. The nipples are both 1/2" diameter.


(Jochen Glöckner) #15


your metal filters sure look a lot nicer than mine, but then the standard white plastic filters I used are cheap and scream at you once they start filling with dirt and debris https://www.motointegrator.de/artikel/195787-kraftstofffilter-mahle-knecht-kl-13-of?gclid=EAIaIQobChMIi6Ct9-nr4AIVTeJ3Ch0G0QGIEAQYBSABEgKievD_BwE.

I put one between each tank and the corresponding pump and am happy to find everything clean and white when opening the fuel pump compartment.


75 XJ6L 4.2 auto (UK spec)

(David Jauch) #16

What are your adaptors? The 8,1mm won’t fit into the hose from the tank to the changeover. Well, it will go in but leak a lot as well.
Wait. You have two pumps in your SII. Stock SIIIs have one pump and a big changeover valve. The lines are 12-13mm ID, 21mm OD. The pump is a FI pump you can find anywhere, no points or diaphragm.

(Frank Andersen) #17

Bearing of course in mind that pump pressure is high…:slight_smile:

xj6 85 Sov Europe (UK/NZ)

(Andrew Waugh) #18

I made a tool for siphoning tanks.

It’s just a length of 8mm clear plastic hose about 2.5m long, with a bit of welding rod stuck to the outside with heatshrink (because fuel will dissolve most tape adhesives) about every 20cm.

To use it, gently feed the end of the tube with the wire down through the fuel filler neck, being careful that you don’t bend any fuel sensor arms, until you feel it hit the bottom of the tank. Place the other end of the hose into a suitably sized container (located lower than the fuel tank). Now feed another bit of hose attached to an air blowoff pistol into the filler neck. Use a rag to close up the top of the filler neck around the pipes - it doesn’t need to be an airtight seal, all you need is to create enough restriction that the path of least resistance is the hose with the wire attached. Give a couple of squirts to the air pistol until you see fuel going past the high point in the siphon hose. Once the fuel starts siphoning you can remove the rag and the air line, and the tank will empty itself.

If there is a lot of crud in the tank it may clog the end of the hose - just give it a bit of a twist every now and then, and it will usually free up the clog.

This won’t get absolutely all the fuel out, or clean the tank, but it does empty the tank well enough that you can remove it for proper cleaning without dealing with the weight of the fuel. If the fuel is just stale, and the siphon doesn’t pick up much rust then just add some Wynn’s Dry Fuel, refill with fresh gas, change your filters and Bob’s your uncle.

(Carl Hutchins, Jr. ) #19

Aye o the preparation for a lot of fuel coming out the tank drains. Been there, done that… thought I was prepared. I was not!!!

Aye, that the only way to be really sure that all the crud is out, is via the lower drains… the large one is better. I got that, although my target was the smaller one. and, to my surprise, the tanks were quite clean!!!

The hard rubber plugs in the valance were ruined in the endeavor. After considerable thinking, I decided the car was better off wi8thout them. In other areas of the planet, perhaps not.

Only once have I succeeded in siphoning fuel from my SIII. A neat little suction device from HF… Two hoses into a hand pump. Immerse one and pump away.

I’ve another in my shed. Been there for decades. Clever, but it never worked for me. I do get the principle. A length of clear hose. A one way valve at the foot, aka a foot pump. Jab it into the tank, valve first. Then push pull. Much like an ancient butter churn.

Doug’s suggestion as to the use of the car’ pump is intriguing…

My motive was to assure that my fresh fuel system get fresh gas…


(Frank Andersen) #20

Sucking at the hose to get the process going is the simplest method, Andrew - though petrol is an acquired taste…:slight_smile:

xj6 85 Sov Europe (UK/NZ)