Lowleveldevil
MEMBER
I’m fitting an IO 360 to a PA 18. Any ideas or pictures on best installation position for airflow performance fuel injection pump. Ideas and suggestions appreciated with pics if possible.
API suggests installing inside the cabin to keep it out of the heat. I didn’t want a fuel pump inside so it’s mounted on the lower right side of the firewall inside a sheet metal box that’s interior is cooled by a blast tube. The front is secured by a couple of quarter turn fasteners. It works great. No hot start issues.
Something which I've thought off but not done, is to install a low pressure switch after the engine driven pump. In case of an engine pump failure or prior to engine start when the engine pump is not putting out pressure the aux pump will automatically be turned on. When the engine pump is putting out pressure the aux pump will be shut off.
Something which I've thought off but not done, is to install a low pressure switch after the engine driven pump. In case of an engine pump failure or prior to engine start when the engine pump is not putting out pressure the aux pump will automatically be turned on. When the engine pump is putting out pressure the aux pump will be shut off.
It is easy to control the amount of prime by the use of the mixture control if the aux pump were left running.I think that would take away the control I now have on how much fuel to prime with for a cold start. I currently watch fuel flow during cold prime and I don't want the pump running any longer than required to give the prime I decided on.
Good point. As I mentioned I had not done this nor had I given the process much thought. Other than I would still have the aux pump on/off switch in the system, so using the pump for prime as you suggest would still be done in the same manner.Also a low pressure switch after the engine driven pump will be switched by pressure from the aux pump. If engine pump fails the aux pump will come on then almost immediately be turned off again when pressure rises. The aux pump will then continuously oscillate on and off and fuel pressure will oscillate around the low pressure trip point by an amount influenced by the switch hysteresis.
The low pressure switching could be made smarter than that but, in my opinion, it's not worth the complexity.
Edit to add - Above assumes aux pump is before engine pump and fuel pressure is sampled after engine pump which it is on both my aircraft.
I think that would take away the control I now have on how much fuel to prime with for a cold start. I currently watch fuel flow during cold prime and I don't want the pump running any longer than required to give the prime I decided on.
Also a low pressure switch after the engine driven pump will be switched by pressure from the aux pump. If engine pump fails the aux pump will come on then almost immediately be turned off again when pressure rises. The aux pump will then continuously oscillate on and off and fuel pressure will oscillate around the low pressure trip point by an amount influenced by the switch hysteresis.
The low pressure switching could be made smarter than that but, in my opinion, it's not worth the complexity.
Edit to add - Above assumes aux pump is before engine pump and fuel presure is sampled after engine pump which it is on both my aircraft.