It shouldn't look like this.
The silver cannister is the swirl pot, the main pump is inside that, the see through pipes come from the 4 Walbro low pressure pumps installed at each corner of the main tank.
you can see the inside of the swirl pot here - the black deposits are decomposed fire suppressing foam - you don't want to find that in your fuel system.
This was the culprit, note the burnt out wire burnt off terminal post and heat damage on the anodised terminal. Nasty.
Regular readers will recall that last week we were having a bit of a play with the BTCC car but had to give up due to a massive petrol leak causing a bit of concern. We only had time for a very quick look and had noted that the tank was distorted but didn't think too much about it and didn't investigate until this week. I have to say when we realised what had happened we were somewhat gobsmacked at how lucky we had been - especially when you consider the 20 odd cars that got destroyed by fire at Power Maxed Racing back in August. Let me explain...
In a BTCC car of this era there are 5 separate fuel pumps - one main high pressure Bosch pump and 4 small Walbro pumps, one located in each corner of the tank. The four small pumps pump fuel at low pressure in to a swirl pot where the high pressure pump sits and takes the fuel that it pushes to the engine. The idea being that no matter how many g are being pulled in any direction the pump and therefore the engine, are never starved of fuel. The tank is a lined aluminium item with rubber mounts for the small pumps and an oval cut out for the pump plate, electrical connector outlet to the roll over valve ( a one way valve that acts as a vent but seals up if the car goes upside down) and a port for the fuel filler pump to attach to. It's all wonderful when it's working well but the arrangement is now 25 years old and not as reliable and wonderful as it once was.
You can see
The first thing we noticed when we started stripping it was that the foam explosafe material was decomposing and little crumbs of foam were everywhere, it's a miracle the injection system was still working and that seemingly none of the material had got past the filter - we will definitely need a new one, it must be clogged.
The second and by far most worrying thing though was when we saw the burnt wire going to one of the four low pressure pumps. Further inspection showed the top of the pump completely burnt and signs of flame damage on the inside of the tank. It was apparent that at some time there had been a small explosion in there, enough to distort all 6 faces of the tank but not quite blow it apart. We don't know when that was, we don't think it was recent but it was a proper eye opener - dicking around with old petrol powered stuff can be dangerous. We would never have seen any sign that there was any danger, all the external stuff looked ok, it was running fine, we had no need to look inside the tank.
We had a couple of conversations with experts in this field including Tony Ryan down in Brighton who was most useful in guiding us towards the best solution - Malc's massive contact list always comes in handy. Thanks Tony, not many people around that know these cars so your input was massively valuable - if anybody needs any BTCC related parts, he's the man.
Anyway we are getting rid of all the complexity, the car doesn't need to be FIA certified any more, there are simpler and safer solutions about now. My idea is to do away with the Walbro pumps altogether and also to ditch the main pump in the tank and install a separate swirl tank with an in tank pump that is fed from a bottom outlet on the main tank. I have to have a look at the logistics of fitting it all but it looks like a good way of getting the reliability that we need while reducing the fire / explosion risk. The car's competition days are over but Malc wants it to be usable for demo runs and the such like, I think we all hope that one day Josh will get to drive it, none of us want it to end in disaster.
So that's where we are now, I need to order the tanks, pumps, pipe, an6 and an8 connectors and then get the job done. Need to do a bit more research, I haven't yet decided whether to have a small low pressure pump between the main and swirl tank, I will give Malc the option and see what he wants us to do.
Some of the decomposing foam, it lasted 25 years.
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