14 replies to this topic

[brad-the-bear]

Hi,

 

i have recently purchased a facet solid state fuel pump (a real one). after having a look on the internet for a couple of fitting ideas (location etc)  a few performance websites have said that the "pulsing" of the fuel leaving the pump can damage the float inside the carb, increasing wear.

 

1. as shown in this video below, the pump does seem to "pulse". Will this damage the float in my weber 45?

 

 

 

2. my desired psi is around 3.5 psi and the pump is 1.5-4 Psi. what does it mean by "1.5-4 PSI"? there is no way of adjusting the pump?

 

3. also if the pump is at the rear will any pressure be lost by the time it reaches the front of the car? 

 

4. do i need a regulator, if so can i mount it at the rear?

 

Thanks in advance,

 

bear.

[cal844]

Id mount it in the boot, with the regulator under the bonnet, id buy an adjustable regulator :)

[Dusky]

Mount it in the boot for sure! desirably under the tank level.

A regulator is only needed for higher pressure pumps ;)
And even then We have a mini with a 6 psi pump, double split webers and no problems yet..

[Danmini74]

As above, pump in boot and regulator in the bay that's how i chose to set it up and haven't had any problems on twin hs4s...touch wood.

[brad-the-bear]

cheers guys  

 

 

 

Mount it in the boot for sure! desirably under the tank level.

A regulator is only needed for higher pressure pumps ;)
And even then We have a mini with a 6 psi pump, double split webers and no problems yet..

what fuel pump are you using

[dklawson]

I would like to make a couple of points. 

 

If pulsing damages float valves then every Mini with an SU fuel pump was designed wrong.  Both mechanical and electrical SU fuel pumps create pulses.  This does not cause problems.  A pressure regulator may dampen the pulses but it is not going to eliminate them.

 

The rating of "1.5-4 PSI " is a possible range of pressure.  Facet is saying that due to manufacturing tolerances of the machined parts and the rate of the spring in the pump, the output pressure could be anywhere from 1.5 PSI to 4 PSI.  The actual value will vary from pump to pump.  It is easily checked by priming the pump with fuel, then connecting a pressure gauge to the discharge side of the pump and powering it up.  That is a static pressure.  A more accurate reading will be found by putting a gauge in a T fitting installed inline with the fuel hose.

 

Regulators have their place but you have to be aware of a few things.  To be effective, the regulator needs to be supplied by a certain amount of pressure HIGHER than what you want coming out.  (Basically what Dusky was saying about regulators are for high pressure pumps).  It would not be unusual for the regulator to need the supply pressure to be 20% higher than your desired output pressure.  As a made-up example, let's say you wanted a constant 10 PSI at the carburetor and you want to fit a regulator.  You would need a pump capable of supplying 12 PSI or more for the regulator to work as designed.  Therefore, if you have bought a 1.5-4 PSI pump and your carb wants 3.5 PSI, measure the pressure your pump develops to see if the regulator is needed at all.    For the regulator to work properly you would need a pump capable of supplying about 4.5 PSI in most cases.  However, I anticipate you will find the Facet pump is going to deliver around 3 PSI which will make the regulator totally unnecessary.

 

I see a lot of people on U.K. boards like putting pumps in the boot.  That's fine but mount it as low as possible.  You want the pump fed by gravity, you don't want the pump to have to use suction to lift the fuel (again... as Dusky said).  When BMC designed the Mini, those models that used electric pumps had them located on the rear subframe below the LH fuel tank.

 

Yes, pumping fuel to the front of the car will create a pressure drop.  How much will depend on the size of your fuel lines and the number and type of filters you install in the line.  However, don't expect your Mini will suddenly need huge fuel lines and a high pressure pump just because you are fitting a Webber.  Yes, it might use more fuel at a faster rate but short of full out racing you are unlikely to tax a stock pump.  What your system really requires is sufficient fuel flow to keep the float bowls full and pressure suitable enough to maintain that flow without overpowering the float valves.

[rally1380]

Have a solid state Facet pump under my boot floor inside the subframe shielded by a nice alloy guard, then got one of these under the bonnet before the carbs

 

http://www.demon-twe...ssure-regulator

 

 

Not had any problems, and not a mega expensive setup.  Running twin SU's, but on a similar pressue.  Was recommended the Sytec Pro flow as it's simple, cheap and the company i got it from (tweeks) say they've never had any returned so seem reliable.

 

Agree with above about pulsing....standard fuel pump pulses like a goodun.

 

Would be interested to test the pressure coming out of my system before and after regulator....will say that experiment for when I'm bored with building new engine!!!

[Cooperman]

Best place to mount a Facet pump is under the rear seat horizontal support panel, towards the left hand side next to the rear sub-frame edge. That way it is always gravity fed from the tank and is not required to 'lift' the fuel from the tank, just 'push' it to the carbs.

I always think it better to keep the electric pump away from the area where the petrol tank & battery are mounted in case the pipes fail and/or the pump connections spark. Maybe I'm just being extra safe.

[Captain Mainwaring]

I would like to make a couple of points. 

 

If pulsing damages float valves then every Mini with an SU fuel pump was designed wrong.  Both mechanical and electrical SU fuel pumps create pulses.  This does not cause problems.  A pressure regulator may dampen the pulses but it is not going to eliminate them.

 

The rating of "1.5-4 PSI " is a possible range of pressure.  Facet is saying that due to manufacturing tolerances of the machined parts and the rate of the spring in the pump, the output pressure could be anywhere from 1.5 PSI to 4 PSI.  The actual value will vary from pump to pump.  It is easily checked by priming the pump with fuel, then connecting a pressure gauge to the discharge side of the pump and powering it up.  That is a static pressure.  A more accurate reading will be found by putting a gauge in a T fitting installed inline with the fuel hose.

 

Regulators have their place but you have to be aware of a few things.  To be effective, the regulator needs to be supplied by a certain amount of pressure HIGHER than what you want coming out.  (Basically what Dusky was saying about regulators are for high pressure pumps).  It would not be unusual for the regulator to need the supply pressure to be 20% higher than your desired output pressure.  As a made-up example, let's say you wanted a constant 10 PSI at the carburetor and you want to fit a regulator.  You would need a pump capable of supplying 12 PSI or more for the regulator to work as designed.  Therefore, if you have bought a 1.5-4 PSI pump and your carb wants 3.5 PSI, measure the pressure your pump develops to see if the regulator is needed at all.    For the regulator to work properly you would need a pump capable of supplying about 4.5 PSI in most cases.  However, I anticipate you will find the Facet pump is going to deliver around 3 PSI which will make the regulator totally unnecessary.

 

I see a lot of people on U.K. boards like putting pumps in the boot.  That's fine but mount it as low as possible.  You want the pump fed by gravity, you don't want the pump to have to use suction to lift the fuel (again... as Dusky said).  When BMC designed the Mini, those models that used electric pumps had them located on the rear subframe below the LH fuel tank.

 

Yes, pumping fuel to the front of the car will create a pressure drop.  How much will depend on the size of your fuel lines and the number and type of filters you install in the line.  However, don't expect your Mini will suddenly need huge fuel lines and a high pressure pump just because you are fitting a Webber.  Yes, it might use more fuel at a faster rate but short of full out racing you are unlikely to tax a stock pump.  What your system really requires is sufficient fuel flow to keep the float bowls full and pressure suitable enough to maintain that flow without overpowering the float valves.

 

No more than sucking it. Flow is proportional to the SQRT of the DP for any given pressure.

 

Actually once the system is primed it doesn't matter where the fuel pump is - the suction head on the inlet will balance the suction head on the discharge. One of the downsides with a suck through system is the possibility of vapour lock during high temperature operating conditions. There is a lot to be said for mounting the pump a little above the level of the bottom of the tank, to prevent gunge build up .

 

Most non-bypass regs are only effective under flow conditions, they tend to let by in no flow situations.

Edited by Captain Mainwaring, 02 April 2014 - 04:13 AM.

[dklawson]

You have to draw the fuel up to the inlet of the pump to prime it and you cannot assume the the valving in the pump will maintain the prime.  Mount a pump high if you want but you are asking for problems.  Pump manufacturers (like the Facet being discussed here) instruct you to mount the pump as low as reasonable and as close to the tank as possible.

 

I frequently see references to fuel system problems occuring when the tank is allowed to go too close to empty or to empty.  The pickup tube inside the tank is not resting on the bottom but is an inch or so off the bottom of the tank.  It will only suck up debris when that debris is floating or sloshing around such as when the fuel level is low.  Since it is the level of the fuel and the amount of sloshing taking place that determines how much debris is in suspension, where the pump is mounted will not offer any protection.  Once the debris is floating about it will get sucked into the pump regardless of where the pump is mounted.  Mounting the pump above the bottom of the tank in no way protects its inlet.  That is why a coarse filter located between the tank and pump inlet is helpful.

 

Rally1380, I am not trying to be a harbinger of doom and gloom, but that is a particularly bad regulator design and I encourage you to replace it.  I was unaware that anyone sold that design in the U.K.  That regulator has been available for 40+ years in the U.S. sold under the Purolator and Spectre brand names (among others).  They have a reputation of poor pressure control and worse... leakage.  In addition to the anecdotal evidence on the web, I speak from personal experience on both counts.  I had one of those regulators on my Triumph GT6.  I found the pressure output did not match the dial and was off by more than 1.5 PSI.  That resulted in float valve related flooding.  Once I sorted that out and got the pressure where it needed to be the unit worked OK for several years.  Then, 4 years ago my wife called from work telling me that fuel was pouring out of the car and she was afraid to drive it.  This particular regulator design uses a large rubber diaphragm and the one in our regulator failed catastrphically.  Some other (but not all) regulator designs work with pistons and o-ring seals which have a better reputation for control and reliability.  Over here the reliable inexpensive regulators are made by Holley.  I am sure there are comparable regulators in the U.K. 

[Captain Mainwaring]

You have to draw the fuel up to the inlet of the pump to prime it and you cannot assume the the valving in the pump will maintain the prime.  Mount a pump high if you want but you are asking for problems.  Pump manufacturers (like the Facet being discussed here) instruct you to mount the pump as low as reasonable and as close to the tank as possible.

 

I frequently see references to fuel system problems occuring when the tank is allowed to go too close to empty or to empty.  The pickup tube inside the tank is not resting on the bottom but is an inch or so off the bottom of the tank.  It will only suck up debris when that debris is floating or sloshing around such as when the fuel level is low.  Since it is the level of the fuel and the amount of sloshing taking place that determines how much debris is in suspension, where the pump is mounted will not offer any protection.  Once the debris is floating about it will get sucked into the pump regardless of where the pump is mounted.  Mounting the pump above the bottom of the tank in no way protects its inlet.  That is why a coarse filter located between the tank and pump inlet is helpful.

 

Rally1380, I am not trying to be a harbinger of doom and gloom, but that is a particularly bad regulator design and I encourage you to replace it.  I was unaware that anyone sold that design in the U.K.  That regulator has been available for 40+ years in the U.S. sold under the Purolator and Spectre brand names (among others).  They have a reputation of poor pressure control and worse... leakage.  In addition to the anecdotal evidence on the web, I speak from personal experience on both counts.  I had one of those regulators on my Triumph GT6.  I found the pressure output did not match the dial and was off by more than 1.5 PSI.  That resulted in float valve related flooding.  Once I sorted that out and got the pressure where it needed to be the unit worked OK for several years.  Then, 4 years ago my wife called from work telling me that fuel was pouring out of the car and she was afraid to drive it.  This particular regulator design uses a large rubber diaphragm and the one in our regulator failed catastrphically.  Some other (but not all) regulator designs work with pistons and o-ring seals which have a better reputation for control and reliability.  Over here the reliable inexpensive regulators are made by Holley.  I am sure there are comparable regulators in the U.K. 

 

No it doesn't but it does give a fall for any solids to drop out, rather than if the pump is mounted at the lowest point where debris are forced to collect.

 

Remember once the pump has initially primed it will stay "in balance", rather like twin pipe systems on fuel oil boiler pumps where the pump has to suck against gravity - the only downside being that there is negative pressure on the shaft seal in the case of a rotary pump..

 

Regarding regulators, pretty much forget what the dial says, unless you have a pressure gauge you are shooting in the dark.

[Dan]

I have a Facet cube pump in the boot and I have to say I wouldn't put it there again and will be moving it under the car when I give the thing a refresh this year. I thought I was saving problems by keeping it clean and dry but it just gets in the way and is incredibly noisy.

[rally1380]

 

Rally1380, I am not trying to be a harbinger of doom and gloom, but that is a particularly bad regulator design and I encourage you to replace it.  I was unaware that anyone sold that design in the U.K.  That regulator has been available for 40+ years in the U.S. sold under the Purolator and Spectre brand names (among others).  They have a reputation of poor pressure control and worse... leakage.  In addition to the anecdotal evidence on the web, I speak from personal experience on both counts.  I had one of those regulators on my Triumph GT6.  I found the pressure output did not match the dial and was off by more than 1.5 PSI.  That resulted in float valve related flooding.  Once I sorted that out and got the pressure where it needed to be the unit worked OK for several years.  Then, 4 years ago my wife called from work telling me that fuel was pouring out of the car and she was afraid to drive it.  This particular regulator design uses a large rubber diaphragm and the one in our regulator failed catastrphically.  Some other (but not all) regulator designs work with pistons and o-ring seals which have a better reputation for control and reliability.  Over here the reliable inexpensive regulators are made by Holley.  I am sure there are comparable regulators in the U.K. 

 

mmmmmmm.......got me thinking now.  Surely modern rubber seals would increase reliability?  I was dubious about it's appearance (nasty chrome!!!) but figured it was american and i stupidly thought that yank made products (probably made in china!) were quality.

 

I liked the design of this one as it's small so doesn't take up too much room in the cramped engine bay.....and it wasn't too expensive, but if it fails on an event then it works out a fair bit more expensive (as i know from recent clutch failure)!!!!!  

 

In it's defence - not had any issues.....Yet!!!!

 

Will have a look at Holley's products though.

[brad-the-bear]

ok, I'm mounting the pump under the boot floor covered by some sort of metal shield, only because i can see myself  cramming something into the boot and breaking something. I'll do without the regulator and fit a in-line gauge to keep an eye on the output pressure. i shall also fit a small filter between tank and pump.

 

thanks for the help fellas. glad i could get a few views on the matter.

 

bear.  

[dklawson]

That regulator design was probably American once but I can all but guarantee that it is now made in China with Chinese rubber.  That doesn't increase my confidence in the Purolator regulator design.  Don't get me wrong, I ignored the advice of others to replace it and once I got it correctly set using a pressure gauge inline it did what it was supposed to do for a decade.  However, the failure mode scared me so much that I threw out the extra one I had bought years earlier.  I will not install one again.  I am sure other U.K. retailers will have a better and safer regulator available.

 

Captain, I have mentioned in several threads (including this one) that I put a coarse filter before the pump inlet to catch the tank debris we are talking about.  The Facet pump (as shown in Dusky's picture in this thread:   http://www.theminifo...acet-fuel-pump/   ) typically comes with a metal intake filter.  I prefer clear so I can see how much debris has collected.  Regardless the coarse filter before the pump is intended to collect debris that would otherwise foul the pump and its valves. I also prefer gravity feeding the pump to avoid using the suction side of the pump to do work.  I do not dispute that once the pump is primed there is no head difference to deal with.  However, if the pump valves don't seal well you can loose that prime while the car is parked.  With both issues, this is your car.  Do as you want with the installation but do follow the pump manufacturer's recommendations to achieve good results and acceptable pump life.