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Fuel Gauge Follow up, frustration and cut fingers!

My struggles with the fuel gauge continue, I ran out of fuel miles from home and I spent 5 hours struggling to remove the boot floor! I did have hoot during the drive, while the fuel lasted.

Last weekend I used the car a fair amount and after being encouraged by Simon Lambert at Caterham Cars to enjoy more of the rev range I'd had a fantastic time until I ran out of fuel. I learnt the hard way my fuel gauge is not just limited to a maximum reading of 3/16, it's also not lowering regardless of fuel level. I guess I lost track and well the inevitable happened, I ran out of fuel. I've since decided I need to sort the problem, it's more of a problem than you'd think.

When discussing the fuel gauge issues with Derek Howlett at Caterham Cars he'd previously requested I send him photographs of the pump orientation in the tank. I believe from speaking with a fellow owner with a similar problem there is a probability the pump if poorly orientated is causing the float to get stuck and hence the poor reading and operation. It was therefore time to get the tools back out and lift the floor to see what was what. Oh my, what a task! 5 hours to remove the floor. Cut fingers from the floor and a lot of cursing, this did not go as planned.

The boot floor in the 7 is made up of two sections, with a brace bar between. A wooden section at the front and an aluminium section at the rear which covers the tank. Removal of the wooden section takes seconds through the removal of a couple of self-tapping screws. It's technically not required when gaining access to the tank, however, given the ease, I removed the wooden section regardless.

Removing the aluminium section is a little more detailed. First up, if you have the revised washer bottle configuration, the washer bottle needs to be removed, followed by the fuel filler neck cover. The cover is secured using two retaining screws.

Next, there is an array of screws securing the floor into place, all face down through the floor. These need to be removed. You may also need to remove a wing bolt near the edge of the aluminium floor.

Underneath there is a fuel pump control assembly bolted underneath the floor, this needs to be unbolted too.

Caterham 7 Blog Fuel gauge self assembly
Pump control assembly, that's going to be fun to re-install !!!

In theory if the above is completed this should permit the floor to lift out. It's a very tight fit, and you need to be careful of the chassis tubes in the boot. I tried for hours to get my floor to lift and failed. Eventually, after much swearing and frustration, my wife asked me about a cradle clip used to retain the fuel hose underneath the floor. Logically I thought this was riveted to the bracing bar, how wrong I was. Turns out Caterham had riveted the cradle clip to the brace bar and into the aluminium floor, subsequently I couldn't remove the floor without removing the cradle clip.

Caterham 7 Blog Fuel gauge self assembly
Cradle clip holding down the floor onto the brace bar.

Removing the rivet from the cradle clip was going to be interesting, with the drive shaft and A-Frame in place it was impossible to use a standard drill. Luckily during my build I'd invested in a cheap air drill with a 90-degree chuck, that went in with ease. A 4mm drill bit made light work of the rivet and I soon had the rivet and cradle clip removed. Immediately afterwards the boot lifted. I've since spoken to the fellow owner suffering a similar fuel gauge issue and his floor wasn't riveted in the manner mine was, I can therefore only put this down to a quality control issue at Caterham. It's disappointing these things are happening, but I am gaining a more detailed understanding of my 7, and I guess fixing the problems.

Having removed the floor I found my pump as shown below.

Caterham 7 Blog Fuel Pump gauge issue
My fuel pump as installed by the factory.

I'm currently awaiting confirmation from Derek at Caterham on the next steps. Based on images supplied by Derek, I believe my pump is offset, and it's probably impacting the float and subsequent reading.

Caterham 7 Blog Fuel gauge issues self assembly
Reference image from Caterham showing correct orientation

Hopefully I need to release the lock ring, rotate the assembly and secure. I believe I may need to replace a gasket too. I'm also still trying to source the correct lockring tool, I've got one on order from Amazon, but it's yet to arrive.

As mentioned I'm awaiting confirmation from Derek before taking further action. The car currently remains in a disassembled state in the garage, which is a shame as the Easter weekend is shaping up to be cracking weather, proper 7 weather.

If the weather is as good as expected, and the 7 is still in bits I may have to revert to detailing the 7. It is my intention to ceramic coat the wheels and paint the side wall lettering white. That might have to be my Easter 7 fun! Future plans also include "de-tango'ing" the front indicators, all going well I hope to be doing that around the last week in April, so please keep coming back for more content.


  • Original blog,

  • 2nd follow up blog,

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