Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing How do you empty a fuel tank?

I've decided to finally fix my fuel gauge (it stays on full for ages then moves quickly to empty). I suspect Morgan fitted a fuel tank sender which was for a bi-metallic gauge but they fitted an air-core fuel gauge.

To do this I need to measure the sender resistance at 1 litre increments from empty to full, hence I need to (safely empty the tank).

My plan is to run the car to 1/4 tank and then siphon out the remaining fuel via the filler cap.

Does anyone know if there is a tank drain plug or a better way of doing it?

There's certainly a tank drain plug in the tanks they fitted in the 1980's, there's a circular hole in the wooden boards that support the tank that provides access to it.

You can see a bit of the hole in this picture, top centre.

The Trad tank sits on the floor boards so no drain on current cars. If you siphon, use a siphon priming tool or electric pump.

I have a funny story about emptying an MGB tank, which did have a drain plug. When I stripped my car, I did it over the pit. I'd run it dry by the gauge, so was confident there wouldn't be much left inside.
The drain plug came out easily, and I used an old plastic bowl to catch the dregs. Unfortunately there was so much rusty petrol left in that tank that it filled the bowl and overflowed all down me and into the pit..............
After I'd jumped around a bit, and stripped off,......you can imagine MrsW's face at that point............
I went back into the garage to survey the mess. I disposed of the bowlful of rusty petrol (can't remember now where that went), and looked into the pit.
The fuel had evaporated, there hadn't been much as it was all in my clothes, but I knew that being heavier than air, in theory the pit could be full of vapour.

There was only one thing to do........
I rolled the MGB out of the garage.
I laid over the pit and sniffed the air......
There was an overarching smell of petrol, but not specifically in the pit.
I left it for a half hour, then lit a taper, and threw it into the pit, before running away fast..............

Nothing happened.
I gingerly crept back into the garage and the taper was burning out in the bottom of the pit.

Just checking..........
But it could have been Darwin award material.

That's a really clean car Tim - I'm impressed.

Not what you are looking for, but when I returned home from the TM visit to MMC, I fuelled up at Shell station near my home. It needed 54.47 l. The tank is supposedly 55l. So just driving and ignoring the fuel gauge prooves to be an effective way to empty the fuel tank. The advantage is that I do know now, that when the needle hits the first marker, its really almost empty.
Cheers,
Bert

That photo was taken 5 years ago, at Kevin Vernon's when I went to collect it after it had its new chassis fitted. It certainly isn't that clean now!

Thanks, I assumed that using a siphon was the way.

I would have thought that the combined fuel pump/sender sits a little higher than the tank base (to stop it pumping the tank sludge).

The safety margin (when gauge shows empty) should probably be at least 6 litres (50 miles) which is around 4cm of tank height (plus the "sludge" height). It might be difficult to siphon the fuel to the real empty point (point at which the engine dies).

Perhaps disconnecting the fuel lines and using the existing pump to pump out the last few litres via a temporary hose might be the best way to get an accurate empty point.

Probably would do this outside and have a fire extinguisher or one of Dave's lighted tapers to hand in case of a leak!

Reading other posts on the fuel pump they mention the fuel line plastic push fit connectors are easy to break (really single use only) so maybe I'll ditch that idea.

I had a 1993 4/4. I overhauled the fuel system which included draining and flushing the tank after running it down to close to empty.There was some "crud" in there but I filtered it out using kitchen towel in a funnel, repeated flushing with clean filtered petrol until none found.It had a drain plug so fairly easy to do.
As a check I refilled it finally in 1 gal stages to note the gauge readings. On level ground with 1 gal it was just touching empty on the gauge. The gauge fluctuated quite a bit during driving so a guide only!

Well, we tried last year, with the AA, rather expensive, I wouldn't recommend.......