Fuel pump and filter routing

[stuart]

He`s a speed freak!

Stuart.

[Rob Y]

On 7/22/2022 at 5:47 PM, Waldi said:

I do not like sharp bends in rubber pipe. The fabricator normally states a minimum bending radius too.

This is how I installed mine.

Hi Waldi,

I’m really interested in this and your set up. I have one of the “kits” which is quite new with the short pipe between the pump and after filter. My set up is really noisy, although it functions perfectly well even in hot conditions. I have a pre and post pump filter.

Your set up looks much better and quite an easy change to make, but don’t you still have right angle out of the pump? Do you have a filter after the pump, or isn’t this really needed?

Cheers, Rob.

[Waldi]

Hi Rob,

the bend radius of the discharge hose is within the allowable range as specified by Gates (Barricade FI hose).

I had to cut a slot out of the boot-floor to create a big-enough radius for the hose.

Opinions on a discharge-filter Y/N vary. I do not have one, FWIW. The original PI design also does not have a discharge filter,  My reasoning was the pre-filter is more important because it protects the pump. In theory, the only particles that can then appear downstream are from pump-wear. Since there is a strainer (nylon gaze) in the PRV, I hope this filters out most of these particles. Off course, a proper modern filter will be more efficient.

 

[Jonny TR6]

I’m using 9.6mm id stainless braided PTFE hose which has a really good bend radius (very flexible) is 100% ethanol proof and extremely high burst pressure.

[john.r.davies]

I do not like sharp bends in pipe

 I feel the same as Waldi 

I would not fit one, no by Cripe!

No more would Fittipaldi!

 

I would not fit one on a car 

I would not fit one in a bar 

Machine made joints may have a place 

But that's the only valid case 

(After Dr.Seuss!)

 

 

 

 

 

 

 

 

 

Edited August 17, 2022 by john.r.davies

[Rob Y]

Am I missing something, isn’t the outlet from the pump through a sharp 90 degrees through the banjo fitting?

Waldi, how long have you been running without the post filter? I guess you’ve not had any issues with blocked injectors. I’m seriously tempted to remove mine and see if this makes the pump run more quietly.

Rob

[Waldi]

34 minutes ago, Rob Y said:

Am I missing something, isn’t the outlet from the pump through a sharp 90 degrees through the banjo fitting?

Waldi, how long have you been running without the post filter? I guess you’ve not had any issues with blocked injectors. I’m seriously tempted to remove mine and see if this makes the pump run more quietly.

Rob

Hi Rob,

maybe the picture makes it look like a sharp bend, but it is not.

Your discharge filter should not cause noise in the pump, the whining etc is normally related yo cavitation in the inlet side. 
And yes, I had a sticking PRV a couple of months ago, to my great disappointment. It was reconditioned in 2017 or so and the car was only used since 2020 after a body off resto. When I opened the PRV I could not see any particles (with magnifying glasses) but found the plunjer had a very very tight fit in the brass seat. I used chrome polish or similar to lap it and it now runs ok. The cause may also have been related to a couple of months without use, I really do not know. So maybe a fine discharge side filter would have avoided this? I will never know (I hope)

Waldi

[Mike C]

2 hours ago, Waldi said:

Hi Rob,

maybe the picture makes it look like a sharp bend, but it is not.

Your discharge filter should not cause noise in the pump, the whining etc is normally related yo cavitation in the inlet side. 
And yes, I had a sticking PRV a couple of months ago, to my great disappointment. It was reconditioned in 2017 or so and the car was only used since 2020 after a body off resto. When I opened the PRV I could not see any particles (with magnifying glasses) but found the plunjer had a very very tight fit in the brass seat. I used chrome polish or similar to lap it and it now runs ok. The cause may also have been related to a couple of months without use, I really do not know. So maybe a fine discharge side filter would have avoided this? I will never know (I hope)

Waldi

+1 for hand lapping the PRV plunger and seat. It makes a real difference to the valves smooth, consistent operation. I use body cutting compound.

[Rob Y]

Ok, I think I’ll keep the post pump filter cos I don’t think this is causing the noise, but from other comments on this thread the connection between the pump and the post filter via banjo fittings and a short piece of tubing  could be.

I want to replace all the rubber tubing with Gates Barricade and it seems a good opportunity to put a longer piece of tubing between the pump and the post filter.

My problem/question is how do I do this, what connections do I need to replace the banjos? I don’t want to use jubilee clips on the pressure side.

Can someone help me with type and size of connections needed please. If I need to get swaged fittings done at a tubing supplier I can do this but I need to know what fittings I need please.

Thanks in anticipation

Rob

[Jonny TR6]

Hi Rob - are you mounting in the wheel well or wheel arch ? A pic of your set up will help.

[Rob Y]

It’s already installed in the spare wheel well.

I’ve pinched this picture from another post on another thread, because it shows pretty much my set up too.

I’m asking about the 2 banjo connectors and pipe between the pump and post filter.

[Jonny TR6]

On 8/18/2022 at 1:52 PM, Rob Y said:

It’s already installed in the spare wheel well.

I’ve pinched this picture from another post on another thread, because it shows pretty much my set up too.

I’m asking about the 2 banjo connectors and pipe between the pump and post filter.

Hi Rob - not sure what hose you’re using in your setup. The banjos are probably 12mm hole which the banjo bolt will go through. I changed my banjos to 12mm hole with 10mm o/d tails, which go into 9.6mm PTFE braided stainless (from Pirtek). The banjo from the pump (I’m not using a post filter) was crimped (again at Pirtek) and goes to a 90degree 3/8 BSP connection to the brass T.

Hope that helps !

[Jonny TR6]

Well - nearly there….

Got the missing pieces connected up (tank to pre-filter hose and MU pipe with built in pressure gauge adapter).

Switched on the ignition and listened to a very noisy pump pushing air for a brief few seconds or so until the fuel got to it.

Then checked everything for leaks.

Sure enough there was a leak - right at the most inaccessible point on the whole system - the 3/8 right angle connector to the brass T.

Out came the crows foot spanner and eventually off came the connector. I’d stupidly used the old connector from the old system before I changed from rubber to  PTFE. It was weeping through the swivel connection to the pipe.

Off to Pirtek yet again to get another hose made up….

Happy days

Edited September 5, 2022 by Jonny TR6

[Jonny TR6]

On 9/5/2022 at 10:18 PM, Jonny TR6 said:

Well - nearly there….

Got the missing pieces connected up (tank to pre-filter hose and MU pipe with built in pressure gauge adapter).

Switched on the ignition and listened to a very noisy pump pushing air for a brief few seconds or so until the fuel got to it.

Then checked everything for leaks.

Sure enough there was a leak - right at the most inaccessible point on the whole system - the 3/8 right angle connector to the brass T.

Out came the crows foot spanner and eventually off came the connector. I’d stupidly used the old connector from the old system before I changed from rubber to  PTFE. It was weeping through the swivel connection to the pipe.

Off to Pirtek yet again to get another hose made up….

Happy days

Every day’s a school day…

I’d rebuilt my fuel system from top to bottom, new hoses, fittings, hose clamps etc and had an annoying leak at the brass T.

The 3/8 BSP right angled connector to the top of the T was the original one and looked brand new, so had decided to re-use it.

There ended up being a leak at the swivel part of the connector, just weeping through, but a leak all the same.

Off to see Tom (yet again) at Pirtek in Liverpool and showed him the pipe.

“Ah” he said, “have you got an inverted flare at the brass T” ? A quick Google showed that I had and it transpired that the connector, despite being the right size, didn’t have an inverted flare on it.

2 mins later and the correct fitting was crimped into the pipe and now no more leaks at the back end. It had obviously been like that ever since the system was originally plumbed in.

Just one small issue to sort out now. I’ve fitted a fuel pressure gauge adapter into the MU feed pipe. This has a 1/8th NPT take off hole with a blanking plug installed.

Despite nipping up the blanking plug firmly, I’m getting a weep from it.

There’s no o ring or washer and the hole and blanking plug aren’t tapered.

Anyone have any experience in this area they could share ?

[john.r.davies]

I built mine from 10mm  central heating pipe and compression fittings.  Never had a leak.

John

[Jonny TR6]

Yeah - but I don't have the space to carry round a boiler, let alone all the radiators...

Spoke to the supplier of the adaptor earlier and they said the blanking plug is tapered and recommended an extra half turn as well as a couple of winds of PTFE.

Edited September 10, 2022 by Jonny TR6

[Mike Heelis]

Hi All, Can anyone help me on the subject of fuel in the tank heating up? The story goes that on a single 480 mile run down from Scotland my old Bosch fuel pump was cavitating on arrival home with just over a third of a tank of fuel.  Foolishly I decided to change it for a replacement in the boot set up with a Sytec pump, Sytec bullet pre filter feeding through a Malpasi diaphragm PRV correctly set.  On another long trip the car cut out due to the new set up overheating at half a tank (no pre warning cavitation).  Not happy so I got a refund for that set up and fitted an outside pump and filter (from a reputable TR supplier) with the same arrangement. This also failed on overheat, but I sorted out the Low Pressure feed to the pump to obviate any requirement for the pump to suck.  Out of interest I have fitted a fishtank temperature gauge to the outside of my fuel tank (with bluetack).  Seems I still have the heating of fuel issue as on a 1 hour run the temperature at the tank gets up to 36 degree's C.  I know the fuel has always warmed even with the Bosch pump as after parking the car post a good run the fuel gauge is always lower when I go to start up from cold again.  Can anyone help by making suggestions of how I can prevent my fuel in the tank from heating up?  It is not from the exhaust as I have put heat shielding above the silencer on the boot floor.  I am running a Sytec HP 3979.1 pump fed through the Sytec Bullet and also a mainline pressure filter into the Malpasi set at just over 100 psi.

[PodOne]

Hi Mike

Seems strange three set ups have suffered the same fate.

Might be worthwhile if you haven't already making a new dedicated 12v supply and earth via a relay to ensure the pump isn't having to work harder than it needs otherwise it will be generating more heat to then impart into the fuel in the first place which some will then be returned to the tank hotter than needs.

I've yet to run my Bosch set up but given the issues people have had I decided to run the return from the MU through a fuel cooler (Taken from a Citroen C4 diesel) then back to the tank installed outside attached to the side of the boot where some people install the pump and installed a bigger outlet from the tank to aid the gravity feed. Time will tell if it makes a difference.

Was discussed in a thread but I can't find it.

Other I'm sure will chip in.

Andy 

[Mike Heelis]

Hi Andy,

Thanks for your swift reply.  My understanding is that there is no high flow return from the MU to the tank as the outlet is in the drive from distributor cavity.  When I disconnect that return line at the tank there is very little fuel in the line.  Also it is very small bore.  Perhaps I am wrong.  I have fitted a cooler of sorts in the Malpassi to tank return line (see pic).  Trouble is that there is no air flow in the boot to act on the return pipe.  I am running a fuel pump relay and have upgraded the wiring - good point though.

[Mk2 Chopper]

1 hour ago, Mike Heelis said:

Hi Andy,

Thanks for your swift reply.  My understanding is that there is no high flow return from the MU to the tank as the outlet is in the drive from distributor cavity.  When I disconnect that return line at the tank there is very little fuel in the line.  Also it is very small bore.  Perhaps I am wrong.  I have fitted a cooler of sorts in the Malpassi to tank return line (see pic).  Trouble is that there is no air flow in the boot to act on the return pipe.  I am running a fuel pump relay and have upgraded the wiring - good point though.

You are correct about the over fueling return line it is very low pressure. 

You are also trying to do the right thing by cooling the PVR return line, as this has been warmed up by the pump and goes straight back into the tank. I too find it odd that with the pump mounted outside and good electrical power your pump is still running very hot and causing this issue. Have you actually checked the amount of amps it's using? 

I guess you could route the PVR return line outside and try a method to cool it before it goes back into the tank. 

Gareth

[john.r.davies]

Mike,

Recently, I had a very similar problem, but probably in a very different setup.    I have a 2.5L engine and Pi in my race Vitesse.   Because of higher cornering forces than on road, it was very vulnerable to cuttting out as the tank emptied, so I have a swirl pot to exclude bubbles, kept full by a Facet pump.    That pump had a problem, the pot wasn't kept full and I kept losing pressure.    So I replumbed it, with the PRV return going to the swirl instead of straight back to the tank.    Afraid that this might cause the fuel to the main pump to be overheated, like you I considered a diesel cooler, but first I              measured the temps:

 

This was idling the engine, over twenty minutes.  I measured the temps with an Infrared pyrometer.   The main pump started a little warm because I had done some basic flow tests first.   As you can see, and as said above the return fuel from the PRV warmed up by about 5C and then plateaued, while the fuel coming out of the swirl pot via the two returns to the tank and to the main pump also warmed but only by about one degree, as cooler fuel from the tank diluted the PRV fuel.    That too plateaued by twenty minutes.      The return from the Metering Unit was till rising but as also said above, that flow is very small and doesn't significantly contribute heat to the tank.

The main pump was still warming up, and I have yet to test it on the road or circuit, by measuring how hot it gets after a run and using 'temp tabs', adhesive stickers that change colour permanently to indicate how hot they get.   The lowest range I could get is 37-100C, so I really hope that they don't register anything!   But for now, I think that these data show that a cooler is unnecessary.

John

Edited October 16, 2022 by john.r.davies

[john.r.davies]

3 hours ago, Mike Heelis said:

  I know the fuel has always warmed even with the Bosch pump as after parking the car post a good run the fuel gauge is always lower when I go to start up from cold 

As above, Mike,, some warming occurs, but the volumetric coefficient of expansion of petroleum is 0.001/C.    So if your tank of about 40L is warmed by 15C, then its volume will increase by 0.001x15x40=0.6L.  I beg to doubt that your fuel gauge can register that small a change!

John

Edited October 16, 2022 by john.r.davies

[Mike Heelis]

Hi John,  Thanks for your input to my problem of fuel warming.  Your chart and measurements are really interesting and useful - thanks.  My PRV return goes straight into the swirl pot at the bottom of the fuel tank.  Previously I have had it placed to the other side of the tank from the swirl, but this did not seem to have any effect on my problem.  I will be measuring the fuel pump amps consumed this coming week and that to will be interesting.  I hear you about the volumetric change and cannot dispute the science.  However I have had the car for 10 years and believe that this is what I have been seeing.  Your main pump body temp is the key one for me as I believe that this is where my heating is coming from with warmed fuel feeding the pump which in turn warms the fuel again on the way to the PRV back to the tank and back again = vicious circle of temp increase. 

[Mike Heelis]

Thanks Gareth for your input about measuring amps which as above I intend doing.

[Mike C]

10 hours ago, Mike Heelis said:

Hi All, Can anyone help me on the subject of fuel in the tank heating up? The story goes that on a single 480 mile run down from Scotland my old Bosch fuel pump was cavitating on arrival home with just over a third of a tank of fuel.  Foolishly I decided to change it for a replacement in the boot set up with a Sytec pump, Sytec bullet pre filter feeding through a Malpasi diaphragm PRV correctly set.  On another long trip the car cut out due to the new set up overheating at half a tank (no pre warning cavitation).  Not happy so I got a refund for that set up and fitted an outside pump and filter (from a reputable TR supplier) with the same arrangement. This also failed on overheat, but I sorted out the Low Pressure feed to the pump to obviate any requirement for the pump to suck.  Out of interest I have fitted a fishtank temperature gauge to the outside of my fuel tank (with bluetack).  Seems I still have the heating of fuel issue as on a 1 hour run the temperature at the tank gets up to 36 degree's C.  I know the fuel has always warmed even with the Bosch pump as after parking the car post a good run the fuel gauge is always lower when I go to start up from cold again.  Can anyone help by making suggestions of how I can prevent my fuel in the tank from heating up?  It is not from the exhaust as I have put heat shielding above the silencer on the boot floor.  I am running a Sytec HP 3979.1 pump fed through the Sytec Bullet and also a mainline pressure filter into the Malpasi set at just over 100 psi.

At the fuel systems/pump's curve  operating point the Sytec  pump is using more power ( and putting it into the petrol) than the Bosch pump. I'd check the Sytec pump isn't oversized. I'd check that the pump delivery pressure to the MU is correct as a first step.

Replumbing the pump to tank return line with a petrol/air heat exchanger outside of the enclosed boot is a bullet proof solution.

I get by with my PRV return line discharging into an alloy tank on the opposite side of the fuel suction line- petrol has to work its way across the tank before it is reheated by the pump. This works in Australian ambient's above 40 degC but  I do use a Bosch pump with a Carter booster pump under the tank.

You've probably  looked at  this already, but is your fuel tank venting correctly?