Fuel return and fuel pump set up for EFI
- Thread starter bigdaddyjoefish
- Start date
Joe,
Not knowing how your fuel lines are set makes it difficult to give advice, unless someone knows your specific car. Just because you have a CAV or any other make, doesn't mean your fuel lines are , or have to be, a certain type. Having said that if you have EFI you will need several things. This is just some of them. Others with specifics will chime in once you tell us what your layout is, or how you want it to be.
1. low pressure fuel pump to pull fuel from both tanks(T or Polluck valve). Pre filter to the pump to ward off any junk in the tanks.
2. pump to a swirl pot(look it up).
3. attach fitting from low point on swirl pot to drain to the High pressure pump.
4. High pressure pump to 100micron filter then to the EFI
5. Have fuel pressure regulator at end of fuel run of EFI. This should be matched to the injectors you are using and are usually a little higher than the suggested flow of the injectors(40# for 32# injectors etc.).
6. Depending on how you set up #1 will determine how you terminate your fuel line. Some use a return to the swirl pot, and an overflow line to the tanks. This helps assure you won't starve the high pressure pump which will kill it rather quickly. If you use a T arrangement then you will need a T arrangement for the return line. To assure you don't overload one of the tanks, a balance line should be in place between the two tanks at their bottoms at mid tank. 3/8 line is probably sufficient. Your low pressure pump can be set up to have only one line to it. That would require a switching valve(Polluck etc.). That has a lot of wiring that will operate the valve to switch tanks when one is near empty. You have to remember which you started off with last time you drove the car so you don't switch to an empty tank unless you have two fuel gauges, one for each tank. The Polluck valve will switch the flow from the tanks and the return to them.
There is a lot more info concerning the fuel system like vents, rollover valves, sealing tank fillers etc. So tell us something about what you have or what you want and we can be more specific.
Bill
Not knowing how your fuel lines are set makes it difficult to give advice, unless someone knows your specific car. Just because you have a CAV or any other make, doesn't mean your fuel lines are , or have to be, a certain type. Having said that if you have EFI you will need several things. This is just some of them. Others with specifics will chime in once you tell us what your layout is, or how you want it to be.
1. low pressure fuel pump to pull fuel from both tanks(T or Polluck valve). Pre filter to the pump to ward off any junk in the tanks.
2. pump to a swirl pot(look it up).
3. attach fitting from low point on swirl pot to drain to the High pressure pump.
4. High pressure pump to 100micron filter then to the EFI
5. Have fuel pressure regulator at end of fuel run of EFI. This should be matched to the injectors you are using and are usually a little higher than the suggested flow of the injectors(40# for 32# injectors etc.).
6. Depending on how you set up #1 will determine how you terminate your fuel line. Some use a return to the swirl pot, and an overflow line to the tanks. This helps assure you won't starve the high pressure pump which will kill it rather quickly. If you use a T arrangement then you will need a T arrangement for the return line. To assure you don't overload one of the tanks, a balance line should be in place between the two tanks at their bottoms at mid tank. 3/8 line is probably sufficient. Your low pressure pump can be set up to have only one line to it. That would require a switching valve(Polluck etc.). That has a lot of wiring that will operate the valve to switch tanks when one is near empty. You have to remember which you started off with last time you drove the car so you don't switch to an empty tank unless you have two fuel gauges, one for each tank. The Polluck valve will switch the flow from the tanks and the return to them.
There is a lot more info concerning the fuel system like vents, rollover valves, sealing tank fillers etc. So tell us something about what you have or what you want and we can be more specific.
Bill
Steve Wood (PANAVIA)
Lifetime Supporter
How much pressure do you need to feed the EFI -- 30-40-60psi >?
There is a neat filter that was used on the 98-2004 corvette which has an internal regulator that regulates the fuel flow at 58PSI, which may be a bit high for some systems , but it means smaller injectors will act like bigger ones. so with 400-450HP you should be able to use 24/32 pound injectors and be able to tune the fuel curve to match. -- I dont think you need to go to 42# injectors.
It also has a second benefit of simplifying the fuel system schematic for fuel lines.
Depending on your setup , I agree with Bill above, that you want a Low Pressure fuel pump to feed a low pressure filter, into the intake of a High Pressure Pump, say a nice Carter or Bosch unit ,- the HP pump feeding this Wix (WIX Part # 33737) filter , with its integrated return line.
3/8 fuel line is fine for 400/450HP - AN6 size.
--Steve
There is a neat filter that was used on the 98-2004 corvette which has an internal regulator that regulates the fuel flow at 58PSI, which may be a bit high for some systems , but it means smaller injectors will act like bigger ones. so with 400-450HP you should be able to use 24/32 pound injectors and be able to tune the fuel curve to match. -- I dont think you need to go to 42# injectors.
It also has a second benefit of simplifying the fuel system schematic for fuel lines.
Depending on your setup , I agree with Bill above, that you want a Low Pressure fuel pump to feed a low pressure filter, into the intake of a High Pressure Pump, say a nice Carter or Bosch unit ,- the HP pump feeding this Wix (WIX Part # 33737) filter , with its integrated return line.
3/8 fuel line is fine for 400/450HP - AN6 size.
--Steve
I've a question regarding filters. I'm building a system with a similar config to that described, but lower power application using an Alfa V6 engine, about 240bhp (disclaimer: Not a GT40 but a Lancia Stratos replica - I just like to frequent this site for the great info and contributors!).
I'm looking at using a holley 'red' low pressure lift pump from the tank to a swirl pot and a Walbro GSL394 high pressure pump from the swirl pot to the fuel rails. There's a return from the pressure regulator on the fuel rail to the pot and another return on the top of the pot to the tank.
I need some help on filter selection though. Do I need a filter before the Holley pump and after the Walbro? Should I have a third in between or two is plenty? What level of filtration should I look for - I'm guessing 10micron on the high pressure line and somewhere in the 50-100 range on the low pressure side, but am not sure. Also, any good recommendations on types - I see multiple sizes and configuration (bullet style, canister, long, short, replaceable elements, etc). I plan to use 6-an fittings, so that's a consideration.
All help and advice will be greatly appreciated
Best Regards
Paul
I'm looking at using a holley 'red' low pressure lift pump from the tank to a swirl pot and a Walbro GSL394 high pressure pump from the swirl pot to the fuel rails. There's a return from the pressure regulator on the fuel rail to the pot and another return on the top of the pot to the tank.
I need some help on filter selection though. Do I need a filter before the Holley pump and after the Walbro? Should I have a third in between or two is plenty? What level of filtration should I look for - I'm guessing 10micron on the high pressure line and somewhere in the 50-100 range on the low pressure side, but am not sure. Also, any good recommendations on types - I see multiple sizes and configuration (bullet style, canister, long, short, replaceable elements, etc). I plan to use 6-an fittings, so that's a consideration.
All help and advice will be greatly appreciated
Best Regards
Paul
I have just installed the fuel system based on what my engine builder reccomends.
I have 456 H.P. and he says no smaller than -8 hoses and fittings.
I have installed the same on a 640 HP chevy and all works a treat.
I also used Aeromatic parts , high flow rates and not too large bits.
Return lines need to be -8 I believe as when the engine idles big pumps will still be pumping loads of fuel an it's got to go somewhere.
This is my set up:
Tank 1 - 100 micron filter - NRV -150gph pump
Tank 2 - 100 micron filter - NRV -150gph pump
>> 10 micron filter - A1000 H.P. pump >
And still to be decided where and what type: two 12v solenoid valves for tank returns, which need to be high flow
I have 456 H.P. and he says no smaller than -8 hoses and fittings.
I have installed the same on a 640 HP chevy and all works a treat.
I also used Aeromatic parts , high flow rates and not too large bits.
Return lines need to be -8 I believe as when the engine idles big pumps will still be pumping loads of fuel an it's got to go somewhere.
This is my set up:
Tank 1 - 100 micron filter - NRV -150gph pump
Tank 2 - 100 micron filter - NRV -150gph pump
>> 10 micron filter - A1000 H.P. pump >
And still to be decided where and what type: two 12v solenoid valves for tank returns, which need to be high flow
Last edited:
Aeromotive is a USA product so probably far cheaper over there than in rip off britain.
There flow rates are very high and the actual size of the component was small, as you know space is a premium so I decided to use them. The agent in UK power services international are very helpfull and they get regular deliveries from the States.
Holley gear looks quality too.
There flow rates are very high and the actual size of the component was small, as you know space is a premium so I decided to use them. The agent in UK power services international are very helpfull and they get regular deliveries from the States.
Holley gear looks quality too.
Seymour Snerd
Lifetime Supporter
Actually having the return line one size larger than the supply line allows the bypass regulator to do a better job. Any pressure it sees on the return line in effect gets added to the regulation pressure it's trying establish (the bypass pressure is its "reference" if you will). If there is any bypass flow resistance at all, when the bypass flow varies, the bypass pressure varies, and thus the pressure seen by the EFI system varies even though the regulator is behaving perfectly.
