frankh
Well Known Member
Ok here is the text describing the installation and operation of Fuel sysytem.
The usual disclaimers.....This is how i did my system..I have no idea of your skills at creating your own system so I want it understood loud and clear that In no way accept any responsibilty for you attempting to do something similar..
I have an electric pump set in each wingroot with no mechanical pump. This was an attempt at providing a ?hydraulically correct? pumping solution for use with auto fuel, maybe even auto fuel containing ethanol. This system overcomes the potential issue with Vapour Lock by placing the pumps at the low pressure point of the system and also avoiding heating of the fuel by heat conducted through the engine block or by placement in a hot environment, namely on the engine side of the firewall.
My system is for a FI?d engine, but a much simplified version can be used with a Carb by simply placing a Facet fuel pump in each wingroot. In this case no pressure reducing valve would be required.
The carb version of this system has been running in my Zodiac for 500 or so hours and the FI?d in the RV7a for almost 300 without failure.
FI'd system:
Each pump set is comprised of a NAPA pump (Part #2P74028), Pressure relief valve from Airflow Performance, a filter (upstream of the pump), a manifold welded together from fittings from my local hydraulics shop (you can also find fittings to thread together, welding is a more compact way to achieve the same thing). A check valve (Andair from Vans) is placed inside the cabin in each feed line to the "Vans selector valve".
Note even though I had QB tanks it was not difficult to plumb the extra returns to the tanks?I plumbed the pressure relief back to each tank, and the purge valve discharge back to the right tank. In order to fit everything in the wing roots I put flop tubes in both tanks?Oh Darn, guess I?ll have to do aerobatics now.. . But you can imitate the same thing with solid tube if you really don?t want to hang in the harness.
The selector valve uses the 4th port so it becomes a simple on/off valve. The two feedlines from each wingroot pump set join together in a Tee..directly below the on/off ?selector valve?. In practice the valve is never oprated.
For TO and landing both pumps are run together, and tank switching is done by running the appropriate pump?Leaving the opposite pump off?Its dead simple in practice.
Make sure each pump is wired independently!!! That means a separate switch and separate fuse/wiring for each pump?No muti function switches which would be a single point of failure.
The two Andair check valves prevents cross feeding from one tank to the other.
The FI system is all AFP but will work equally well where the servo is OK with constant fuel pressure.
The following message will contain the pics. The only thing you can?t see is that I tapped out the ends of the fuel pump to 7/16ths UNF (for a standard #4 ORB fitting) this replaces the standard #3 ORB (at 3/8ths UNF)?.This is easily done on a drill press. Make sure to stuff some shreds of paper towel down the pump to stop shards of metal getting in the pump.
My filters are the cheap paper kind (metal jacket) but I will probably replace those with a sintered bronze filter (Summit racing) if I have to switch to ETOH fuel.
I also have a final filter in each feedline but to be honest this is overkill..well as long as a pump does not break a chunk of rotor of it is.
Thats the basic system and I'm delighted with it.
Frank
Pics to follow
The usual disclaimers.....This is how i did my system..I have no idea of your skills at creating your own system so I want it understood loud and clear that In no way accept any responsibilty for you attempting to do something similar..
I have an electric pump set in each wingroot with no mechanical pump. This was an attempt at providing a ?hydraulically correct? pumping solution for use with auto fuel, maybe even auto fuel containing ethanol. This system overcomes the potential issue with Vapour Lock by placing the pumps at the low pressure point of the system and also avoiding heating of the fuel by heat conducted through the engine block or by placement in a hot environment, namely on the engine side of the firewall.
My system is for a FI?d engine, but a much simplified version can be used with a Carb by simply placing a Facet fuel pump in each wingroot. In this case no pressure reducing valve would be required.
The carb version of this system has been running in my Zodiac for 500 or so hours and the FI?d in the RV7a for almost 300 without failure.
FI'd system:
Each pump set is comprised of a NAPA pump (Part #2P74028), Pressure relief valve from Airflow Performance, a filter (upstream of the pump), a manifold welded together from fittings from my local hydraulics shop (you can also find fittings to thread together, welding is a more compact way to achieve the same thing). A check valve (Andair from Vans) is placed inside the cabin in each feed line to the "Vans selector valve".
Note even though I had QB tanks it was not difficult to plumb the extra returns to the tanks?I plumbed the pressure relief back to each tank, and the purge valve discharge back to the right tank. In order to fit everything in the wing roots I put flop tubes in both tanks?Oh Darn, guess I?ll have to do aerobatics now.. . But you can imitate the same thing with solid tube if you really don?t want to hang in the harness.
The selector valve uses the 4th port so it becomes a simple on/off valve. The two feedlines from each wingroot pump set join together in a Tee..directly below the on/off ?selector valve?. In practice the valve is never oprated.
For TO and landing both pumps are run together, and tank switching is done by running the appropriate pump?Leaving the opposite pump off?Its dead simple in practice.
Make sure each pump is wired independently!!! That means a separate switch and separate fuse/wiring for each pump?No muti function switches which would be a single point of failure.
The two Andair check valves prevents cross feeding from one tank to the other.
The FI system is all AFP but will work equally well where the servo is OK with constant fuel pressure.
The following message will contain the pics. The only thing you can?t see is that I tapped out the ends of the fuel pump to 7/16ths UNF (for a standard #4 ORB fitting) this replaces the standard #3 ORB (at 3/8ths UNF)?.This is easily done on a drill press. Make sure to stuff some shreds of paper towel down the pump to stop shards of metal getting in the pump.
My filters are the cheap paper kind (metal jacket) but I will probably replace those with a sintered bronze filter (Summit racing) if I have to switch to ETOH fuel.
I also have a final filter in each feedline but to be honest this is overkill..well as long as a pump does not break a chunk of rotor of it is.
Thats the basic system and I'm delighted with it.
Frank
Pics to follow