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IO-320 fuel plumbing diagram
- Thread starter edclee
- Start date
Fuel
I don’t have any excess fuel but plumbing exists for it. I understand that a method for keeping fuel cool to prevent vapor is used by some to circulate excess fuel through the system
I don’t have any excess fuel but plumbing exists for it. I understand that a method for keeping fuel cool to prevent vapor is used by some to circulate excess fuel through the system
newt
Well Known Member
Not with the usual "Bendix" style fuel injection system found on most IO-320s.
Not much need for a diagram (but there's one here if you really want it); Usually the flow goes from the tank selector to the electric boost pump (with a bypass), then through a filter, then to the mechanical fuel pump on the engine's accessory case, then to the inlet on the fuel servo. From there it goes up to the "spider" flow divider on top of the crank case, then out to the injector lines to each cylinder.
If you're using the EFI system, or a few other more "niche" ones, you might have different arrangements. Consult their documentation.
- mark
Not much need for a diagram (but there's one here if you really want it); Usually the flow goes from the tank selector to the electric boost pump (with a bypass), then through a filter, then to the mechanical fuel pump on the engine's accessory case, then to the inlet on the fuel servo. From there it goes up to the "spider" flow divider on top of the crank case, then out to the injector lines to each cylinder.
If you're using the EFI system, or a few other more "niche" ones, you might have different arrangements. Consult their documentation.
- mark
planenutz
Well Known Member
As Mark has correctly stated, the Bendix FCU's used on the IO-320 typically do not have a return line. Some engines (usually larger engines and especially common on Continentals) have an "unmetered return" which is a fuel return line delivering the unused fuel at the servo back to the tank, and this is done because the delivery from the pump exceeds the amount of fuel required at that particulat time. This return line has a constant flow of fuel back to the tank during engine operation, however it's not something you have to worry about on your average IO-320/360.
If you employ an Airflow Performance fuel servo they usually provide a Purge Valve in the kit and the idea behind this valve is to allow the operator to purge the hot fuel from the fuel system back to the tank prior to a hot start. The Purge Valve is mounted with the Distribution Valve (Spider) on top of the engine and when installing this you need to run a return line back to the tank, but fuel is only present in this line when the engine is stopped. If you have the plumbing installed for this then it is likely the original builder was intending to fit an AP fuel system to the aircraft - or did, then removed it. Associated with this system is the Purge Valve control lever in the cockpit as you need a way to control the valve, obviously. Do you have this installed? I would assume not. To help answer your original question, the fuel returned from this Purge Valve is typically returned directly back to the tank although you could also send it back to somewhere like the fuel selector or some other location in the fuel system on the aft side of the firewall. On my RV-6 I have this line going back to the right tank and I have a red push/pull control (similar to but quite different to the Mixture Control) in the panel for Cut-off/Purge functions.
I hope this helps.
If you employ an Airflow Performance fuel servo they usually provide a Purge Valve in the kit and the idea behind this valve is to allow the operator to purge the hot fuel from the fuel system back to the tank prior to a hot start. The Purge Valve is mounted with the Distribution Valve (Spider) on top of the engine and when installing this you need to run a return line back to the tank, but fuel is only present in this line when the engine is stopped. If you have the plumbing installed for this then it is likely the original builder was intending to fit an AP fuel system to the aircraft - or did, then removed it. Associated with this system is the Purge Valve control lever in the cockpit as you need a way to control the valve, obviously. Do you have this installed? I would assume not. To help answer your original question, the fuel returned from this Purge Valve is typically returned directly back to the tank although you could also send it back to somewhere like the fuel selector or some other location in the fuel system on the aft side of the firewall. On my RV-6 I have this line going back to the right tank and I have a red push/pull control (similar to but quite different to the Mixture Control) in the panel for Cut-off/Purge functions.
I hope this helps.
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