Pipe from Fuel filter To PRV

[Mike Morris]

I am replacing all pipework in the boot due to the overwhelming smell of petrol. At the moment, pipes go from tank to an old Bosch pump then to a fuel filter then to a screwed union? then to PRV. I have new R9 fuel pipe and a Sytec bullet filter to go in.

Is there any reason that I can't go direct from the filter to the PRV valve?

[Mike C]

No, provided the screwed union isn't needed for any component maintenance.

[Andy Moltu]

Is the screwed union an adaptor to enable the use of the metric thread on the high pressure output from the filter to a standard flexible high pressure pipe to the PRV? Usually has a copper washer between the filter and adaptor.

There is often a short pipe linking the pump to the filter with banjo connections which has a short length of “plastic” pipe between them. This short pipe is an interference fit and sooner or later works a bit loose and allows minimal amounts of fuel to weep almost imperceptibly leading to the fuel smell in the boot. I know some will throw their hands up in horror but the plaggy pipe can be replaced with a short length of correct spec high pressure hose double jubilee clipped. (It is difficult to get a suaged pipe made in such a short length).

An alternative is to fit a fine filter on the inlet side of the pump which is easier to seal with regular ethanol proof pipe and ditch the high pressure filter. You can then fit the adaptor directly to the pump and use a new “standard” pump to PRV high pressure hose or get a pipe made up to suit the Bosch metric threads at one end and the imperial threads at the PRV end. If you go this way, get 2 pipes made so you have a spare if a pump needs replacing when you are on the continent. You could move the pump (and possibly the filter too) out of the boot/spare wheel well and have fewer potential fuel smell causes in the boot, but bear in mind some of the fuel smells are unburned fuel from the exhaust vapours being sucked back into the boot/cabin.

If you go for the inlet filter option, many use the Sytec bullet filter but it’s also available for rather less from here and seems identical in all but name. 

[Mike Morris]

Thank you. Not home at the moment but will poat a pic in the morning

[Mike Morris]

apologies for delay, got called away.

See pictures on fuel pipe routing. Looks a mess to me? going to replace all rubber so 8mm from tank to 8mm banjo to pump then 8mm from pump to filter then 8mm direct to PRV.

At the moment, it goes 8mm from tank to 12mm? via a bastardisation to the pump. Only had the car 6 weeks but is starting to feel as if it is the car that Jack built. Any pointers gratefully received.

[TR NIALL]

Save any confusion.

[TR NIALL]

Hi Mike that looks like a bit of a Rats NestI’m sure you could come up with something a bit neater than that.

[Mike Morris]

I used to be at sea, where we would call it a bunch of b**tards instead of a rats nest

[harrytr5]

Welcome to our world Mike. The TR6 is a fine TR.

This is how I replumb and fit the fuel pump outside.

I use Speedflow for almost all my fittings and the braided hoses are teflon lined using their aircraft spec fittings. Not cheap but you only want to do it once so fit the best

Good luck sounds you are a hands on.

Regards Harry (on EFI since 2010)

[roy53]

On 8/9/2024 at 5:57 PM, Mike Morris said:

I am replacing all pipework in the boot due to the overwhelming smell of petrol. At the moment, pipes go from tank to an old Bosch pump then to a fuel filter then to a screwed union? then to PRV. I have new R9 fuel pipe and a Sytec bullet filter to go in.

Is there any reason that I can't go direct from the filter to the PRV valve?

Should it not be Tank - filter - pump - prv

in that order.

Over 100psi in the filter ?  Not for me.

Roy

[Mike Morris]

6 hours ago, roy53 said:

Should it not be Tank - filter - pump - prv

in that order.

Over 100psi in the filter ?  Not for me.

Roy

Different views on this topic Roy, filter rated at 10 bar which is far greater than pump output.

[Mike C]

6 hours ago, Mike Morris said:

Different views on this topic Roy, filter rated at 10 bar which is far greater than pump output.

A lot of people like to minimize pressure drop on the pump suction line.

Maybe use a low pressure drop roughing filter on the pump suction line followed by a finer , high pressure filter between the pump and MU.

[OldBob]

On 8/17/2024 at 4:50 PM, Mike Morris said:

Different views on this topic Roy, filter rated at 10 bar which is far greater than pump output.

Not necessarily - the pumps can make 150psi - had a Lucas one once that measured up at 160.

Yes, we set the fuel line to the MU to around 95-105psi ish but output from pump can reach & possibly exceed 10bar.

Bob

 

 

 

[Andy Moltu]

I had a noise like a motorbike in the boot, reving up and down - eventually traced to my Bosch pump struggling to keep pumping when the PRV had stuck. It measured 155psi!

All went quiet when the prv had been cleaned out and the gum removed with T-cut!

[Mike Morris]

Well, replaced all pipes and unions to fuel tank, new filter and STILL a smel of fuel in the boot ??? I cant see any leaks and used so much talc in the boot it is like a boudoir. The pump and PRV are the only things not changes but no sign of a leak anywhere?

Wife complaining of smell of fuel in the garage. What could it be?

[TR NIALL]

10 minutes ago, Mike Morris said:

Well, replaced all pipes and unions to fuel tank, new filter and STILL a smel of fuel in the boot ??? I cant see any leaks and used so much talc in the boot it is like a boudoir. The pump and PRV are the only things not changes but no sign of a leak anywhere?

Wife complaining of smell of fuel in the garage. What could it be?

What type of Fuel Hose have you used?

[Mike Morris]

R9

[stuart]

22 minutes ago, Mike Morris said:

R9

What about the filler neck pipe?

Stuart.

[Rob Y]

I’ve also heard that the gasket for the fuel sender can be a source of fuel smell in the boot. Tricky to fix because it seems the tank has to come out.

On Wheeler Dealers it was a hole in the tank itself causing the problem.

Unfortunately once the easy things are done without solving the problem it means that only harder solutions are left.

 

Rob

[John L]

I found the fibre washer on the drain plug was just a little damp, and the washers on the sender unit as well can leak a bit.  Moss do an ethanol proof seal for the sender.

John

[TR NIALL]

3 hours ago, Mike Morris said:

R9

The reason I ask is you have 6/8mm ID pipe from the Tank to the Pump the Pump needs 16mm at the inlet how did you overcome that.

[Chris Hale]

R9 is quite an old spec hose I think the current spec is R14

[Waldi]

14 hours ago, Chris Hale said:

R9 is quite an old spec hose I think the current spec is R14

R9 and R14 are both part of a US specification, SAE J30, just different grades (properties).

The main advantage of R14-grades is they have a lower permeability for ethanol containing fuels (less stench).

The rated burst pressure of R9 is higher, but is not comparable with the burst pressure of R14 because unleaded fuel is used for testing R9 hoses.

Burst- versus working (operating) pressure:
The burst pressure cannot be used as working pressure, because there should be a safety margin, and additionally, the operating temperature influences the allowable working pressure.

Waldi

[Mike Morris]

The pipe from tank to pump is 8mm or 5/16 and the pump inlet was 10mm, the pipe went straight on with a little persuasion

[roy53]

So you are already restricting the flow by 2mm