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Hi Patrick,
according to Mark, if you don't use a swirl pot, you get fuel starvation when you go round a corner and all the fuel moves to one side of the tank.
( I took his word for it and ordered both pumps and swirl pot from Marlin.)
You'll need a low pressure pump at the back of the car to pump the fuel from the tank up to the swirl pot mounted next to the battery at the front. You then need a high pressure pump from the swirl pot to the engine EFI. The return pipe from the EFI fuel rail goes back to the swirl pot and the return from the swirl pot goes back to the tank.
The swirl pot keeps a constant fuel supply to the engine. It's actually just a small square tank with four connections. I'll send you a picture to your email address.
Although Marlin call it a swirl pot I think it would be better described as a surge tank. The problem is that there are no baffles in the fuel tank. So if you tank is say only half full and you pull away quickly the fuel all goes to the back of the tank and the engine is sucking air. Of course if you never plan to pull away quickly or always have a full tank it wont be a problem
For how much it is and the pain of retrofitting I think it is worth fitting from the start.
I beleive some of the early fuel tanks did have baffles so probably wouldn't need a surge tank.
BTW - still having problems mounting my AFM - I am on to the MkIII bracket now. Someone told me that mounting it direct to the engine (which was easy and I had done) is not good as the AFM contains a very fragile thermocouple arrangement that would not last long with the vibration from the engine.
I've got a nice fuel pump someone gave me already which is why I'm a little hesitant of going for the "swirl pot" option. I suppose if the tank is always 1/2 it would be less of an issue but I see what you mean about pulling away quickly and the fuel sloshing to the back. Might have to dig into my pockets again...
...The problem is that there are no baffles in the fuel tank.
That's disappointing. Surely the fuel tank should have baffles? I understood that a single plate (with cutouts) down the middle of the tank was adequate for this, so it's not like it'd cost much to factory fit.
Hi guys,
I have a sportster i built in 1997 with sierra cosworh engine. I have standard large fuel tank. I do get a problem with fuel surge once the tank gets below a 1/3 if i accelerate hard. I was going to modify it but never got round to it and it doesn't cause too many problems. I thought about the special foam they use in race car tanks which prevents surge, the only problem would be the float would need clearance. I suppose if you haven't put fuel in the tank yet it could be fitted with baffles.
