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Help banishing cockpit fuel smells - advice on fuel pipe replacement


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Like many, I have experienced over a number of years significant fuel smells in the cockpit of my 74 TR6 PI.

I am running with what I believe to be the original boot-mounted Lucas fuel pump, steel fuel tank and rubber fuel lines.  All of this sits behind the standard hardboard “bulkhead”.

I am planning to remove the bulkhead and replace with a metal bulkhead, and intumescent sealer, to completely seal the boot off from the cabin.  I will of course check the state of the tank for any rust holes while doing this.

The main area I need help is with the specification to help me order a number of lengths of fuel pipe which I believe is the biggest contributor to my fuel smells in the boot, which then seeps into the cabin.

My initial plan is to use different sized Gates Barricade 4219BF to replace all existing runs and returns everything from tank to pump, PRV, in and out of the boot towards the metering unit. Can I please ask what sizes (internal diameter), lengths, as well as details of what fittings I will need to completely re-fit all fuel lines within the boot area? 

Before I embark on this refurb project, I would gratefully appreciate any/all advice and guidance from all contributors.

Thanks in advance

Josh

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I have a non standard fuel system involving a Bosch main pump and a Carter booster pump so I can't help you with  a bill of quantities. I kept the steel lines that went the length of the car and used high pressure Gates Barricade at  the boot and MU ends. You'll need to consider a loop ( I have about a 300 mm diameter) of Barricade in the PRV return line to the tank to stop resonance. You also need to decide whether you want to keep the original pump suction diameter- are you getting fuel vaporization on hot days?

I installed a 0.9mm steel bulkhead behind the seat and sealed it with Sikasil 670 Fire. It's fixed in place with bolts and rivnuts. 

The biggest reduction in fuel smells in my car came from having the injectors and MU rebuilt and recalibrated- when I received the before and after fuelling curves my car was running approximately 25% rich once manifold vacuum rose above 5" Hg- and the before smell was terrible- I had to change clothes and shower after a long run. After the fuel system recalibration the smell disappeared and the engine power and responsiveness was massively improved.

 

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Mike,

Thanks, I am definitely keeping the steel lines in place. The smell is definitely coming from the rear end - inside the boot - every time I open it, the smell is intense, its permeated the carpet, and anything left in the boot gets a strong odour.

I haven't experienced any fuel vapourisation on hot days.  There are no smells discernable from within the engine bay, when engine running and I've had injectors rebuilt,although I think MU could do with a tweak to help the engine run a bit more lean.

Will continue down the path of checking fuel tank, sender and fuel lines as next step...

 

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Unfortunately you have to take the tank out to get at the drain plug, unless you have a lift or a pit.

I havent seen it but you can get a rubber/silicone gasket for the fuel gauge, the cork is not so good, may also need some little plastic/aluminium washers for the attaching screws to be sure of a good seal there also.

John

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Moss Europe sell a fuel sender unit Viton gasket. I used it recently and worked well. Lots of potential sources for fuel smell in boot but I suspect the fuel sender unit seal was main culprit in my TR6. The old gasket was cork and extremely brittle and some evidence of fuel stains around it. Viton gasket is far better as seal.

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  • 1 month later...

I have also been trying to tackle the fuel smell in the boot.

Pump, PRV , fuel lines and neck gasket were replaced about 3 years ago.

I talcum powdered all the joints , when for an hour's run and noticed a very, very slight weep around the thread of one of the connectors.

pic of both top connections, one dry, one damp around the thread.

Would this be enough to cause a smell in the boot.

If I remake the joint, would a coating on the thread of Hylomar blue be suitable?

IMG_7043.jpg

IMG_7042.jpg

IMG_7045.jpg

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The thread is not where this joint seals. It is a metal to metal fitting from the pipe end to the tank.

 

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On 4/28/2021 at 12:47 PM, Martin50 said:

Moss Europe sell a fuel sender unit Viton gasket. I used it recently and worked well. Lots of potential sources for fuel smell in boot but I suspect the fuel sender unit seal was main culprit in my TR6. The old gasket was cork and extremely brittle and some evidence of fuel stains around it. Viton gasket is far better as seal.

Cork gasket material is not recommended for E5 petrol as per a test report that I have!

Bruce

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On 6/13/2021 at 5:15 PM, Phil H 4 said:

Is the fuel resistant?

Phil,

Seems we share similar problems with fuel smell.

I agree with the advice you have received, definitely looks like the gland is not fully tightened and as has already been mentioned by Waldi, it is not the thread that seals the fuel, it is the mechanical action of the pipe, olive, and tank coming together in compression....

Will call you to schedule a get together, given you are in CSP, and I'm in GX...

Josh

 

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On all screwed connections that have a metal to metal “seat” (like small “mushroom” or “trumpet” at the end of the pipe that fits into the opposite component you should not apply any sealant. Examples: fuel inlet and outlet connections.

If a NPT (tapered) thread is providing the seal then I recommend using a sealant, although NPT should not need that, it is considered to make a metal to metal seal. It is very important to clean both threads, and remove any debris, corrosion, old sealant etc from both parts. Example: gear box and differential plugs.

For a rubber pipe clamped on a metal tube with a (jubilee or similar) clip, like at the fuel outlet, no sealant is recommended before sliding the rubber pipe on the metal.

On the high pressure side of the fuel lines, I recommend crimped connections, but some TR-ers on here feel a double jubilee clip is sufficient.

 

So to answer your question: if you have the original setup, you will not need any sealant on the pipes from pump to prv and from prv to mu, since they all should have a metal to metal seat.

Waldi

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