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Electrical Wiring: Nothing from Caterham yet despite pleas, so I've gone into reverse engineering mode. Here's a diagram I made of the existing pump module/fuel tank harness wiring. Everything is known except for a mystery GY wire that goes to the pump module. My hope is GY is some kind of engine running signal but I won't know until the job is done (it's not ignition it didn't switch on when I cranked the engine). .... Based on some testing I did the current system energizes YW for about 1 second after turning the key to the 2 position (YG154 energizes), which pressurizes the fuel lines in preparation for cranking and starting the engine. Then presumably the mystery GY wire will switch the pump on full time. The system I'm building will have a pressure regulator with a return to tank so this pulse is probably not needed and can just stay on full time with the key in the 2 position. I'll be cocking about with this once the system is ready to startup as I don't know whether the control module should/can be eliminated yet, but in terms of electrical wiring it's a pretty simple change. At least there's a plan, hopefully it's correct! Note from the future: GY wire was a pump run command from the ECU. Plan A is best if you have an unlocked ECU. Plan B also works but stays on even if the engine is stopped so is not quite as safe.

Caterham sent 3 pics of a bag tank installation that's in for service right now.... The first pic shows a pressure regulator (yellow part) with return to tank and presumably line to rail but cannot be seen. The metallic part before that looks like a sampling device (I guess they have that in the UK). I don't believe that'll be needed in the US unless someone thinks otherwise. Caterham did not include either of these parts in the original shipment so this has spawned more questions. This is the mount location for the pump, which is very helpful. No filter though, another question. Bottom up view of pump installation. It mounts to the tank box.

Make sure the port and screw is clean, use a fresh copper washer each time you take the screw off.

It was the inertia switch that caused the cut off, I guess the ribbed curb on the exit of oak tree caused it to trip. That doesn't explain the vibration/loss of power still but at least the cutout is explained!

Could spray soapy water on the good tank cap to see if even that one is leaking air?

The old tank is removed. There aren't many technical points to note for disassembly except that the tank is lifted out not lowered, so the roll cage and dampers needed to be removed to allow aluminum honeycomb and then tank removal. One item that is unknown right now is whether the drivetrain needs to be removed to allow fuel pipe installation. The existing fuel pipe is mounted under the topside of the tunnel so it's pretty much inaccessible without removing the drivetrain. The hope right now is the new pipe can be installed without having to do this. Cross fingers! For the installation I'm waiting on 3 bits of info from Caterham to move forward... 1. New tank mounting: The old fuel tank was 91cm wide, the new bag tank container is 80cm wide. So the lower black tank brackets on the car are too wide for the new tank (55mm gap each side), see picture below. I've asked what the correct mount method for the underside is. 2. Electrical Wiring: The original tank had a ford/rover pump and tank level sensor which was connected with a 6 pin connector with 4 wires to the tank. The new tank has a Bosch external pump and no tank level, and 2 wires for the pump only. See pics below. The questions to Caterham are: a. Do I keep relay AU5A-9D370-FC and existing wiring intact? (I believe yes) b. Which of the 4 wires connect to the 2 pump wires? (I think pink and yellow). Original 6 pin connector with 4 wires: •Pink/White •Black •Green/Black •Yellow/White 3. Pump and Filter Mount Location, plumbing: I've asked Caterham for info about where they normally mount the pump and filter, plus pics of the plumbing. I really have no clue about this part.

Yes

Started the disassembly…straight forward so far though the aluminum honeycomb doesn’t come out of the top, hopefully it drops down after the tank is removed. Anyone know how to remove the fuel line shown in the pic below??

I have 65mm gap for lowest point to ground (I have dry sump so this is the bell housing). It was lower than that initially but I had issues when running over curbs. Since I raised it to the current position I haven’t had a problem. If you drive pot holed roads you may need to raise.

I think I’m in the minority but when I asked about IVA trim with the tech folks apparently some of it is only used for kit builds in the UK, for factory build they don’t use it. No idea why except stupid government regulation. I basically only used IVA stuff that actually had an obvious function like grommets. The edge trim for the exhaust for example I started to put on but didn’t like the look of it so I took it off, still off today.

You trying to so some aero thing or just avoid hitting stuff underneath?

Good idea, we checked fuses they are good. I'm currently on my 2nd beer so I think I'm done for the day . Thanks for all the quick replies, you guys are awesome!

Thanks guys for the pointers. A mechanic took a look under the tank to listen for noise when I turned the car on. No noise at all. Took off the fuel hose - no fuel. The end of the last last track day I did run out of gas, which was a bit embarrassing, but maybe that caused some damage to the pump? Not sure if that can cause damage.

Wiring looks good, no fraying, everything connected solid. There’s no gas smell coming out of exhaust when turning over. I think the fuel pump may be toast it did all of 1,300 miles, I guess it wasn’t designed for track days!

I’m at ViR today, did warmups and started feeling a weird vibration when higher speeds (95+) that when it came on the car was losing power, almost like a lost cylinder. Then the vibration disappeared and the engine came back to full power, it did it on the straights mainly. Then during the first session (still not pushing hard) it kept doing it again pretty frequently, then the engine cut completely. Any ideas where to start looking? Is that an indication of a fuel pump problem or maybe wiring? I have no idea. When I took the lid off the spark plug cover was loose (the 2 bolts had shaken off I guess). Don’t if that’s coincidence… Any suggestions appreciated!

Nice improvement, the standard one looks (and is) really cheap looking like it's been taken from a 1980 Ford Escort.

What Croc said. Is it not handling right?

I think you're going in the right direction, shouldn't the white line in the last pic be at 100%?

My TPS was 1.1V for 0% and 4.7V for 100%, if I disconnect the TP the feedback goes negative. For the byte used on CAN ID: 0CBB0001 for TPS feedback the range was 60 decimal to 239 decimal. 0v=0, 5V=255. No idea how this relates to your TPS but maybe a frame of reference. You seem to be getting numbers going backwards which makes no sense. Maybe its comparing feedback to 5v instead of 0v which would indicate a wiring issue?? No idea.

How about this? https://www.4statetrucks.com/trailer/semi-truck-metric-wheel-stuf-m22-x-1-5-inches_43822.asp

Yikes! Yeah I’m trying to replicate the Caterham factory installation with as much of their parts as possible, I think I’m most of the way there with the materials with the exception of odds and ends like off the shelf mounting hardware and maybe fuel hose.

Caterham said the internal fuel pump cannot be used with the fuel cell, so I got a new external one that they use for their race spec 420R. I took a peek inside the new tank and it’s full of this sponge material so maybe that’s why, dunno. The parts list doesn’t seem complete, I can’t see how the pump and filter connect right now, plus the new tank is much larger than the existing, so the aluminum honeycomb is going to have to come out, which means the roll cage has to come out, which means the rear dampers have to come out lol. ThIs is not going to be quick or easy.

Group 11X I think, some of the cars in that group are 10 seconds a lap faster, the 420R is not really going to be competitive, it’s just an excuse to hang out with some neat folks and amazing cars at iconic tracks.

I’m working to get my 420R eligible to race in the HSR series, they have all the usual safeties as a requirement to enter, all of which I already have with the exception of the fuel cell. It’s taken almost a year to get the cell and parts due to the supply chain disruptions in the UK plus not knowing whether to keep the internal fuel pump vs getting an external one and a bunch of other stuff that I really have no business trying to make decisions on. I couldn’t find any fuel cell installation posts anywhere (maybe someone knows of a place?) so I figured I’d document this attempt. Here’s the shipment from Caterham of parts and the certificate from ATL... I have no clue right now what the pumps mount to and how the lines are plumbed. Definitely not the straight swap I was hoping for, but it’ll be a fun challenge. Gonna start the install after a VIR track day next week. This is the parts list... Stock code Quantity per Description 1221310053 2.000000 BRACKET COIL & ROVER FUEL 30T043A 2.000000 ADAPTOR-FUEL FILTER TO 380T0001A 1.000000 FUEL HOSE - PUMP/FILTER TO FUEL RAIL 5249970000 1.000000 FUEL PUMP-REMOTE VX RACE 73013 1.000000 BOOT BOARD-99>DD(H/COMB)- 73014/55 1.000000 55 LITRE FUEL BAG TANK-UN 73015/55 1.000000 55 LITRE BOX FOR BAG TANK 73052R 2.000000 BOLT-FUEL TANK RETAINING- 73055R 1.000000 BRAIDED FUELLINE-TANK/PUM 73213 1.000000 FUEL PIPE-INJECTION ROVER 76151 1.000000 EXTENSION-FUEL PUMP-ROVER 79714 1.000000 BOOT BOARD-90> DE DION EDP9976 2.000000 O-RING-FUEL FILTER ADAPTE GFE7020 1.000000 FUEL FILTER-RACE INJECTION (+ROVER) HEF7-6-5 1.000000 FUEL UNION-FOR BAG TANK WG17 1.000000 GROMMET-H'BRAKE CABLE IN WKB100250 1.000000 FUEL PIPE ASSY-FILTER TO ZFT04K 1.000000 HARDWARE FUEL SYSTEM Note from the future: a lot of plumbing parts in the list above ended up being unused or not needed, consider your own solution. Boot board was also not needed. Also there is a new GT bag tank that is a virtual straight swap and a lot simpler to install (with the exception of mounting if you have an SV).

Just go fast