The Early Model Lycoming Fuel Pump
(40174/40295 low pressure, 40595 medium pressure, 40296 high pressure)
In the spring of 1964, AC introduced the first dual diaphragm type fuel pumps. These pumps were the first models to incorporate the oil seal integral with the upper diaphragm and a separator ring for installation of the vent / overboard drain line. These pumps are characterized by a rocker arm which is an early riveted, laminated design. Current production in Lycoming pumps will not fit some pre-1978 applications without expensive modifications. You can eliminate the need for these modifications by ordering an FAA Approved overhauled early model pump for direct replacement.
The Late Model Lycoming Fuel Pump
During August of 1978, AC introduced what is now known as the "late model" fuel pump which has a "channeled" rocker arm. This pump is taller than the early laminated arm pump and has a unitized diaphragm assembly. Because of its increased size some pre-1978 model aircraft require expensive and time consuming modifications to carburetors or accessory housings (ref: Lycoming Service Inst. No. 1110C). These modifications are not required if our smaller, early model laminated fuel pumps are installed on your aircraft.
Download Tempest Fuel Pump Application Guide for Lycoming PDF
Download Tempest Fuel Pump Application Chart for Lycoming PDF
It works like it should. My old pump failed letting fuel into the oil. Reading on the web these pumps should be replaced every 10 years! It was exceedingly difficult to install with the tight firewall clearance in my homebuilt. I had to use spray gasket sealer to hold the gasket in place. With the crank turned to the higher plunger position the plunger pin would not stay up with grease but after I finished I read that someone did that with wire lacing cord. The allen wrench interferes with the sides of the pump so you cannot feel when tightening if the plunger is up or keep it up. I had to grind down the sides of allen wrench to make it possible to feel if it was staying in place plunger up.
Thanks, excellent help as always!
Note that the Tempest pump, AF15473, *does* come with a gasket. You do not need to order a gasket separately for that pump.
Good quality from a company that I trust. Works as expected.
Aircraft Spruce shipped this right away. five starts to them. This fuel pump is NOT the exact same size as the Lycoming fuel pump, so you may ned to modify your shroud. Everything else seems first rate, thats why 4 stars.
Depends I bought this unit to replace the one I bought 2 months ago which failed.
The LW15473 is taller than the ADF15473 pump. They may not fit all the same applications due to the size.
The flow rate of this fuel pump is 45 GPH (gallons per hour). The operating pressure is 24-30psi.
LW15473 is a high pressure fuel pump and LW15472 is a low pressure fuel pump.
We could not find any info on flow rate, but the application chart lists this unit as 4-6 PSI.
Yes, the AF15472 & LW15472 are the same, and the AF15472 does come with a gasket.
No, AF15472 has a channel arm.