T

tullow

Member
Hello to all,
I've looked through the fuel system/fuel injection threads but haven't found an answer to my problem so I'm posting here in the hope that some of you may have some ideas.
My RV7 Quickbuild ( IO360) is almost ready for engine runs and hopefully first flight. I fuelled the airplane for the first time this week,about 10 gals. a side,
and checked for leaks,no problem from tank to Andair selector valve. However fuel does not flow from the selector outlet to the Airflow Performance pump downstream. The installation instructions for the pump state that the pump must not be run dry, so though I've run the pump for about 10 secs. it does not pump fuel. The pump package is standard as supplied by Vans with the exception of the fuel filter ( I replaced theirs with a Flow Ezy ILA2 40 micron filter that I had from another project) and is installed as per their plans.
I have a fuel flow transducer for my AFP 30 installed between the pump outlet and the firewall ( as per the AFP30 installation instructions)though as this is downstream of the pump I imagine it shouldn't affect the operation of the pump.
My questions are:
- Do I need to "prime" the fuel lines through the fuel selector to start the pump pumping?.
- Is it possible to wire/run this pump in reverse?. I wired red to 12v and black to ground.
I have checked and rechecked the "plumbing" of the selector and the pump installation and they are as per plans.

Any help or ideas would be much appreciated.

Many thanks

Mike
 
This is a common problem. I put a piece of hose over the fuel vent outlet under the belly, and gently blew in it for a minute or so to push fuel up to the AFP pump. The pump was OFF when I was pressurizing the tank, and it worked when I tried it afterwards.
 
tullow said:
Hello to all,
I've looked through the fuel system/fuel injection threads but haven't found an answer to my problem so I'm posting here in the hope that some of you may have some ideas.
My RV7 Quickbuild ( IO360) is almost ready for engine runs and hopefully first flight. I fuelled the airplane for the first time this week,about 10 gals. a side,
and checked for leaks,no problem from tank to Andair selector valve. However fuel does not flow from the selector outlet to the Airflow Performance pump downstream. The installation instructions for the pump state that the pump must not be run dry, so though I've run the pump for about 10 secs. it does not pump fuel. The pump package is standard as supplied by Vans with the exception of the fuel filter ( I replaced theirs with a Flow Ezy ILA2 40 micron filter that I had from another project) and is installed as per their plans.
I have a fuel flow transducer for my AFP 30 installed between the pump outlet and the firewall ( as per the AFP30 installation instructions)though as this is downstream of the pump I imagine it shouldn't affect the operation of the pump.
My questions are:
- Do I need to "prime" the fuel lines through the fuel selector to start the pump pumping?.
- Is it possible to wire/run this pump in reverse?. I wired red to 12v and black to ground.
I have checked and rechecked the "plumbing" of the selector and the pump installation and they are as per plans.

Any help or ideas would be much appreciated.

Many thanks

Mike
Click to expand...

Mike,

I am using a similar pump (built by Airtex, I believe) left over from the Subaru effort. The pump will run backward if hooked up wrong. Check the leads with a volt meter to confirm they are correct. While it should not run dry, it will suck fuel up hill if there is no restriction downstream. It will not compress air, the line going forward has to be free to get things flowing. If nothing else, open the line forward of the firewall and run a hose into a bucket until the pump is wet.

With regard to the fuel flow device, it has a very small opening and there is a pressure drop across it. It is not a good thing to be sucking fuel through it which is what you will be doing when the electric pump is off. A pressure drop is where a vapor lock will occur first although fuel temperature is a factor also, it should be relatively cool in the cabin most days. If the electric pump will be run continuously, it does not matter, if it is a take off and land operation, the fuel flow device would work better after the engine driven pump. AFP recommends installing it between the FM-200 and the flow divider.

 
Thanks for your replies,
I was unable to get back to the hangar until yesterday.

Kevin, I did just as you said and it worked first time, sometimes the simple,commonsense solutions are the best.

David , as far as the fuel flow transducer position is concerned ,I have had conflicting information from the Flight Data Systems AFP30 installation manual and Airflow Performation manual as regards the ideal position of the fuel flow transducer. I probably leave it as it is for the time being and see how things go during my first engine tests next week.
Thanks again, its great to know that there is such a wealth of information and experience available amongst the Vans community.

Best regards

Mike
 
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