Citroën BX – XPO – Fuel Pipes – Eps37b

9 min read

Engine bay preparation complete, I decided it was time to tackle the old fuel pipes on XPO. Unfortunately, the pipes that ran through the engine bay had been cut short and were not usable. Thirty-year-old rubber fuel hoses will have lost their flexibilty and should be replaced as part of normal maintenance. With the engine out and no exhaust in place, it seemed a perfect time to overhaul the fuel system.

Tank Inspection

Before attempting to recommission the fuel system, I wanted to check the fuel tank visually. The easiest way to do this is through the fuel level sender hole. Opening the back seat and removing the inspection cover exposes the top of the fuel sender. The area around the sender head can then be thoroughly cleaned. Finally, the fuel sender unit was unscrewed, withdrawn and put somewhere safe.

Fuel tank is inspected for contamination.
Fuel tank is inspected for contamination.

A bright white and compact torch then helps to illuminate the situation. Remember, this tank contains highly flammable petrol! Surprisingly, despite the years off the road, the fuel tank has no obvious contamination. No water sat under the old petrol, no grit or dirt, and nothing living inside the small bit of the tank I can see into.

Fuel Filler Flap

If I want to put fuel into the tank, then at some point, I need to open the fuel filler flap. Easy peasy, I have the key. How hard can it be? After far too long trying to coax the key to turn the lock and release the flap, I accepted defeat. Fortunately, the flap can be disconnected from the locking fuel cap without damage. The fuel cap, however, needed some permanent mutilation to get it free of the car.

The locking fuel flap is dismembered.
The locking fuel flap is dismembered.

With some penetrating fluid, heat, a hammer, and generally sweary language, I eventually managed to separate the pieces of the locking cap. The reason the lock would not turn became quite apparent.

Tumblers are completely seized in the corroded lock.
Tumblers are completely seized in the corroded lock.

The lock itself was completely corroded, with the brass tumbler being jammed in the aluminium housing. No amount of penetrating fluid, heat or even force would have resulted in the lock releasing. Destroying the cap was definitely the right thing to do.

The lock housing is also heavily corroded.

There are several seals to stop water from entering the lock mechanism, along with drains in the cap to let any water back out. Clearly, something has not worked as it should, and water has been trapped against the aluminium parts. After getting this lock to pieces, I went and lubricated all the other BX fuel flap locks. I would prefer if they don’t meet the same fate.

I still haven’t tracked down a replacement lock, but I’ve had a few offers I need to follow up on.

Which replacement fuel lines?

What hoses should I replace?

All rubber hoses on a 30 to 40-year-old Citroen BX probably need replacing by now. Flexible fuel lines get their floppiness from Volatile Organic Compounds (VOCs). The compounds allow movement in the host material by the very nature of being volatile. However, over time, the VOCs escape their host material into the air. This means all BX fuel hoses will be stiff at thirty-plus years old, if not hard. While not an immediate danger, stiffened pipes where they should be flexible are more likely to result in sudden tearing or splitting. This sudden catastrophic failure is likely to be in a hidden bent pipe where visual inspection isn’t easy.

What to replace the fuel pipe with?

In several past articles, I’ve discussed my preference for Gates Barricade fuel lines. I originally found out about the Gates Barricade fuel lines thanks to a long suffering BX friend at Southways Automotive. Their business has used Gates Barricade as the go-to for hose for many years in their TVR restoration business. Personally, I have now been using the Gates Barricade hose for four years, without any issues.

Gates Barricade fuel pipe is my go-to
Gates Barricade fuel pipe is my go-to

Which fuel pipe diameters will I need?

Gates is an American brand, and so the available sizes are predictably imperial. While imperial, the nearest metric equivalents are shown in the table above. Generally, the equivalent sizes are close enough not to cause concern. Unfortunately, the BX uses multiple dimensions, including some half sizes. The underbody hard lines are 10mm and 8mm outside diameter, so I try to get a hose that matches these. The next problem is that some BX hoses are flared (made bigger) at one end. I take a judgement call if I need to fit a bigger internal diameter pipe and reduce it down, or a smaller pipe and try to force it onto the join. Generally, the former approach is more successful.

How much fuel pipe will I need?

The length of hose required will depend on your vehicle variant and engine type. For the Citroen BX 16Valve, the breakdown of the hose elements is shown below. It should be noted that this is very much an artist’s impression of the pipes. None of the hoses really look like the drawing.

The Citroen BX 16Valve fuel pipe arrangement is quite complex.
The Citroen BX 16Valve fuel pipe arrangement is quite complex.
Fuel pipe breakdown shows the lengths and diameters.
Fuel pipe breakdown shows the lengths and diameters.

As a general guide, I aim for two metres of the 10mm ID hose and three metres of the 8mm ID hose. Unfortunately, buying Gates Barricade by the metre is incredibly expensive—up to four times the cost of buying a reel.

Bulk buying Gates Barricade.

Buying the Gates fuel hose is best done in bulk, ordering a whole reel (or box) in one go. This means buying either a 4.6m or 7.6m length. This is typically enough to do three cars, so it can be worth sharing a purchase with other BX owners.

Gates Barricade fuel pipes that I use.
Gates Barricade fuel pipes that I use.

The 8mm ID and 10mm ID hoses come in 15- and 25-foot lengths. I have always struggled to buy the shorter length of the larger bore pipe. This means the Gates Barricade part numbers I ordered are 27348 and 27341, as in the table above.

The most worrying issue with using the Gates Barricade hose is the price increase in the last three years. The shorter 8mm ID has increased by 50%, while the longer 10mm ID hose has risen by a whopping 80%. Availability has also dropped significantly, with many suppliers listing stock but having no hose to fulfil orders!

Is Gates Barricade the only option?

The Gates Barricade hose is a great product. It is hard-wearing, well-lined, and from a reputable manufacturer. There isn’t a fake version in the market, so the product seems like a safe bet. But the Gates Barricade is not the only quality fuel hose out there. I’ve seen reports of premature failure of the Gates hose in some applications. I suspect this may result from the minimum bend requirement not being met. I’d love to hear if you know a cheaper, more readily available hose that has the same compatibility!

Front fuel pipes

I’ve shown my method for replacing the less accessible pipes before, so I won’t get into too much detail here. Compared to previous fuel pipe replacements, the process is much easier with the car on a lift. Having the engine and wheels out of the way also helps.

Cord is tied to the old fuel pipes to help guide replacements back in.
Cord is tied to the old fuel pipes to help guide replacements back in.

The old pipes are drilled through with a 6mm drill bit and some cord tied onto the end. The cord will be used to draw the new pipes along the same path.

Original Citroen fuel pipes, just 30 years old.
Original Citroen fuel pipes, just 30 years old.

The 7mm and 9mm original pipes will be replaced with 8mm and 10mm, respectively. These original pipes are very stiff after 30 years of exposure to the air.

New fuel pipe is secured to the hard fuel pipes.
New fuel pipe is secured to the hard fuel pipes.

The new Gates Barricade fuel hose is cut to length and pulled back along the original path. Fortunately, the cord helps draw the pipe through the protection sleeve. Finally, the protection tape is removed and the new pipe is pushed onto the metal fuel lines. Don’t panic, the nasty hose clamps in the picture where replaced with stainless fuel hose clamps, once they arrived.

Rear Fuel Pipes

The rear fuel pipes are made of many small and tricky pieces, which require a fair bit of manipulation. I like to give the rear a good clean first to avoid getting too much filth into my eyes. And wear goggles, of course.

Cleaning the rear end was definitely a requirement for this car. The long-range tank immediately behind the fuel filler flap traps a lot of dirt, and XPO was no exception. For a car off the road for so long, I expected more mud to have fallen out by now.

But it most certainly had not fallen out. With a few seeds and a little bit of water, I could grow a decent garden with this mud.

Fuel Filter

While I’m in the rear of the fuel system, it seems like a good time to change the fuel filter.

The fuel filter that XPO arrived with (top) might be the original one from the factory. It is undoubtedly the proper shape to be an original. However, it has no date stamp with which to compare. I’m surprised that the new Bosch filter has the same part number ( 0 450 905 002) but looks very different. Is this linked to the move of production from Spain to Bulgaria?

I enjoy taking filters apart to inspect for damage. In this case, the folded paper filter is hidden inside the canister. The soft metal body is no match for a pair of pliers and is soon opened up. This filter certainly needed changing, but it has done a good job of keeping dirt out of the injectors.

Fuel Pulsation Damper

The Bosch Motronic system requires a fuel pulsation damper in line after the fuel pump. The idea is to give a more consistent fuel flow to the injectors. An internal rubber diaphragm absorbs any high-pressure pulses from the pump. On the Peugeot installation, the damper is accessible in the engine bay. On the BX, the damper is attached to a rubber mount on the rear subframe. In all that dirt I removed earlier.

I’ve taken to a standard practice of removing or plumbing past these pulsation dampers. Usually, there is little of the mild steel body left. Amazingly, the fuel damper body on XPO is intact! This is genuinely the best condition damper I have ever seen. Unfortunately, the outlet spigot has not fared well and would result in a major fluid leak if used.

If you don’t want to replace all the original flexible hose, then you can bypass the damper. I use a length of hose from the fuel filter, connected to the original pipe with a barbed inline connector. As a significant weak spot, bypassing this badly placed component is highly recommended.

Ready for the engine?

Well, that’s the engine bay and rear-end fuel pipes replaced, the fuel filter renewed, and fuel pump tested. I feel nearly ready to put the engine back into XPO and drive off into the distance. How hard can it be? Finally, the car is ready for the engine. I just need to get the engine ready for the car!


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