Just a query really, it's not a 306 but i know there are some knowledgeable people on here so thought it was worth asking just for other peoples opinions.

My dad has a Caterham which has been sat for the last few years unused, last year he decided to get it out and take it to a show, on the way back it started spraying fuel everywhere and eventually lost all drive.
When we got it home we discovered it was the mechanical fuel pump at fault - the diaphragm had perished so after a bit of thought we decided to update it a little and fitted a blanking plate on the block where that pump went and fitted a facet silver top fuel pump.

We did that and put a clear fuel filter just before the inlet to the pump so we could see fuel flowing through, then had the pump, then continued with the old setup going through a filter king, then through a fuel cat (which supposedly helps with engines that are meant to run on leaded fuel), then on to the weber carbs.
The carbs have been jetted years ago and ran perfectly back then, recently we balanced them and set the idle mixture right for them so the car was running fine before these problems.

A few years ago the fuel tank developed a leak so instead of replacing the ally tank my dad decided to get some like epoxy repair stuff which you put in the tank when it's empty/out the car, and keep rotating it until it's covered all sides of the tank, then you leave it to set. I removed the fuel level sender last year and noticed this coating has started to come away in places, so i'm suspecting that there could be some of this debris blocking the fuel supply hole in the tank, or stuck in the fuel line before the first filter somewhere.

Since having the electric fuel pump there have been two instances where the engine starts losing power, then refuses to rev and eventually dies a death. Both times after letting the car sit for a couple of minutes at the side of the road it will start ok and usually drive as if nothing ever happened. This happened again tonight when we took it out for a shakedown before its annual trip to a kit car show. I took the bonnet off tonight after it had been stood and watched as my dad turned on the ignition, as the pump started fuel rushed into the first filter and filled that up with plenty of air bubbles, i couldnt see the filter king's glass bowl as that sits inside the nose cone area but i imagine that was similar.

I'm pretty certain it's a fuelling issue, i'm just not sure if its possible that the old fuel that had been sat in the carbs could have gunked them up and caused an issue with the float level needle setup which stops the carbs accepting fuel and that messes up the whole fuel delivery system, or what i think is more likely which is that theres some blockage somewhere between the tank and the first filter.
One other thing I want to question, how/why is air getting into the first filter, i've turned it so that the outlet going to the pump is at the highest point so the pump sucked all the air out and only left fuel in there, then somehow after a while there is air back in there again, and the amount of air can vary over time, you can't smell fuel at any point with the engine off and pump running so i'm inclined to say there isnt any leaks in the fuel lines.

The carbs are twin weber 40 dcoe's, the engine is a 1700 crossflow for anyone thats interested.

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Goldie the track car.

Yep old fuel in the tank can get very sticky and leave a gummy residue, would be worse in the jets and the floats i guess. If there was a blockage on the inlet side of the filters you would see air drawing through the filter bowl.

Found the issue, its the epoxy tank resin that was used to stop the leak ages ago, looks like it's not all that fuel resistant after all...




Had the tank out today and removed as much as possible, there was plenty of bits just flopping around in there which would then block the fuel pickup tube at random and cause fuel starvation. It even did it once when i removed the fuel line from the carbs and was using the pump to fill the jerry can when emptying the tank, so i turned off the pump and used a footpump to blow a bit of air back up towards the tank and it cleared it and the pump then moved fuel fine again afterwards confirming this was the issue.

Ideally it needs a new tank to solve the issue but since we need the car sorted for next weekend and i'm very busy at the moment we're using this old tank again for the time being.

I reckon the carbs do need stripping and cleaning though as i'm not convinced it's running perfectly at certain rev ranges, although i guess carbs will never be as good as throttle bodies especially with reasonably lairy cams.

Thanks again for your help guys.

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Goldie the track car.