Marlin Fuel Tank

[P_Hill]

Hi All
I built my Sportster in 1997 using the Marlin aluminium fuel tank which has been fine but I've broken down twice now, the first time I thought it was the electric fuel pump so I bought a new one, last night I broke down again with same symptoms of running out of fuel. The fuel pump is running but it not drawing it from the tank and the pump is located just inches away from the tank.

Yes I have plenty of fuel in the tank over half full.

Does anyone know if they used a flexible fuel hose inside the tank? I'm thinking the ethanol may have effected the tubing causing the walls to close up preventing fuel flow.

I plan to drain the tank and remove it for inspection.

[greyV8pete]

Re: Marlin Fuel Tank

Why would it need a flexible hose inside the tank? The tank outlet to the pump should be at the bottom. I would expect any connection at the top of the tank to be for a return line from a swirl pot or fuel vapour separator, depending on whether you have fuel injection or carbs? The favourite for fuel blockage is silicone sealant around the sender gasket. It swells up when immersed in petrol and if it breaks off will block the outlet pipe, so should never be used for this application.

[milliemarlin]

Re: Marlin Fuel Tank

I am not overly impressed with the “standard” fuel tank. I can’t remember the configuration of my sportster (still under construction) but I did modify it to add a sump and fuel take up at the bottom of the tank. My Cabrio tank was similarly modified.

The original Cabrio tank had the take up and return on the offside top of the tank. Take up being extended to near the bottom by a straight copper pipe with a slanting end. It worked ok with a mechanical pump but would starve the engine of fuel going round a large roundabout. I believed this would wreck an electric pump because they should never be run dry.

The revised tanks also have baffles to reduce the sloshing.

I can’t decide on a course of action with regard to E10.
Paul

[Peterx]

Re: Marlin Fuel Tank

Hi All
I built my Sportster in 1997 using the Marlin aluminium fuel tank which has been fine but I've broken down twice now, the first time I thought it was the electric fuel pump so I bought a new one, last night I broke down again with same symptoms of running out of fuel. The fuel pump is running but it not drawing it from the tank and the pump is located just inches away from the tank.

Yes I have plenty of fuel in the tank over half full.

I'd check that your tank vent is working properly allowing air in to replace the fuel as it's used up.
Slowly remove the fuel filler cap and see if you can hear a rush of air?

[P_Hill]

Re: Marlin Fuel Tank

Thanks for the replies, my Sportster is number 3 a very early Sportster so early they hadn't even written a build manual so I was given a Cabrio build manual, in fact I helped Mark & Terri with info on developing the car so my tank doesn't have the outlet on the bottom like the latter ones.
The first thing I did was check the tank was vented, it was all ok, I'm certain something has come a-drift inside the tank preventing the fuel pick up. The photos I took on a 35mm film don't show the tank in any real detail, I think it is retained with just two steel straps from underneath. I know later tanks were constructed with a swirl chamber and a bottom pick up and additional baffles were added. I'm not sure if my tank had an internal clung on a flexible hose to move with the fuel as it sloshed around.
When I find the problem I'll report it here.