Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Adding fuel stabilizer for storage with twin tanks

I was adding some fuel stabilizer for winter storage and the tanks were almost full. It got me thinking about the twin tanks and if I add stabilizer at the fuel inlet, will it get to both tanks if I go for a drive or would it likely stay in one tank? How do they work?

It's better for distribution within the fuel system to add the stabilizer before filling the tanks. The M3W fuel system is a return type that constantly circulates fuel from the right tank to the injectors and back to the right tank. There is no inherent circulation of fuel from one tank to the other, but there is transfer of fuel between the tanks as the fuel level rises or falls. This transfer is accomplished by the alloy transfer tube down low near the front of the swingarm. So pouring the stabilizer into a parked up vehicle will not give a good distribution between the tanks as the fuel filler goes only into the right tank. You could take the machine out for a spirited end of season drive before parking it up and that should do a fair job of mixing the stabilizer with the fuel in both tanks.

It would be helpful here if Morgan had followed Ferrari's (mid engine) practice of suppling fuel to the engine from one tank and having the return line plumbed into the other tank as that ensures fuel (and any additives) circulate throughout the fuel system.

Also, practice of topping up the tanks before parking for the winter doesn't really accomplish anything with non rusting alloy tanks. And most of the fuel stabilizers sold claim to greatly reduce or eliminate evaporative fuel residue and fuel tank corrosion.

Makes sense. Next year, adding stabilizer prior will be the way to go. Thanks

It would be helpful here if Morgan had followed Ferrari's (mid engine) practice of suppling fuel to the engine from one tank and having the return line plumbed into the other tank as that ensures fuel (and any additives) circulate throughout the fuel system.



I recall once sitting in the pitlane at Goodwood behind a GT40 replica that had the fuel pumped from one tank to the engine for fuel injection (kinsler system) and then back to the other tank but did not have a sufficient balance pipe between tanks so with the combined fuel in the car at that time of both tanks being greater than the capacity of one tank, a fountain of fuel eruped out of the fuel filler cap as it pushed past the sprung filler cap seal! Quite a drama followed as you can possibly imagine!

They may have missed the necessity of an air balance tube mounted to the tops of the tanks (which I didn't mention in my earlier post). You need both!

How hard would it be to replumb this in the 3W?

Why?

They seem to have worked OK for 10 years without.

Not terribly difficult, but there is no point in doing so.

There is quite a bit of fuel movement between the tanks caused by warmed fuel coming back from the engine and creating pressure differences above the fuel (esp in hot weather). This can give huge swings in the fuel guage reading (if any believes those anyway)

There will be no pressure difference between the two tanks as they are connected above the fuel by a pressure equalization tube, and the entire system is vented to atmosphere through the carbon canister. So no pressure buildup occurs.

The huge swings in fuel gauge readings are more a function of the it's design: the sensor float slides on two fine wires (and can mechanically hang up) and the wires are prone to fuel residue accumulation (which causes signal variation as the wires (with the float) provide a sliding resistive signal). With recently cleaned fine wires and frequent use the fuel gauge is reasonably accurate. Let the machine sit for a few weeks at a time and accuracy becomes hit or (mostly) miss.