HAS ANY BODY PUT AN ELECRIC FUEL PUMP ON A 701? I AM TOLD THAT IT SHOULD NOT BE NESSARY TO DO SO BECAUSE THE FLOW FROM THE WING TANKS SHOULD BE SUFICENT TO KEEP THE ENGINE (912UL) RUNNING IF THE MEC PUMP FAILS.
An electric facet pump with an output of 3 - 4 psi (so as not to cause flooding by over powering carb. floats) is used in series with engine mechanical pump. Install between gascolator and mechanical pump. Aircraft Spruce part# 40105 cost is $34.50.
Cheap insurance when your mechanical pump quits...and your over hostile terrain for landing. Install the pump for safety reasons..I did in both my CH601HD and CH750.
It is true that the head should be sufficient in the event of a mechanical failure... JUST. However, there are more challenges than that. For example, purging lines in a hurry! We always fit a mechanical pump as a backup - and we always use it when we purge the lines before connecting to the engine....what if you change tanks and need a boost for a few seconds? For the small cost, it would be wise to install one - you never know the day you might need it, and if you dont - the day you might regret it!
It is equally important to install a fuel pressure gauge - so that you know when you need to switch on the electric backup unit!!
Scotty - Even a mechanical pump gauges fuel pressure. If it fails physics dictate that fuel would flow into the carbs but in unregulated pressure. Thats were the problem comes in, rather or not the floats would be overwhelmed by the free flowing fuel. So if the mechnical pump should fail you still need regulated fuel pessure and thats where the electric back-up comes into play. But I must state it is possible that the fuel would flow at the proper pressure without the back-up, it depends on the volume of the tank at the time. But why gamble with your life for the $40 cost of the back-up electric pump?
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