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
Not the fault of the pump, but installation is a little tricky. If you feel any resistance while tightening the screws - Stop! - the plunger is not aligned correctly with the arm. Best to hold the pump in place while inserting the mounting screws. Tricky to do with limited working space. Worked perfectly once installed.
AF15473 TEMPEST NEW FUEL PUMP
Finally got the pump installed had to pull the mag which really made it easy to install the pump. Tight working spaces on an RV7 had to cut an Allen wrench to fit between the pump and prop control mounting. Works as advertised 30 psi Thanks for including the gasket and “O” rings putting the safety wire back was a little time consuming
Worked perfect ,thanks again Aircraft spruce!
Perfect replacement for my Lycoming IO360. Well made and perfect fit. Works great.
A quality fuel pump that is working like it should. I was hesitant to change this on my homebuilt after reading several horror stories on a popular forum. If you follow the instructions that came with the fuel pump......it is a straight forward procedure that can be accomplished easily. You do not need heavy grease, or a piece of string to hold up the push rod........just follow the instructions!
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.
Please note, Aircraft Spruce's personnel are not certified aircraft mechanics and can only provide general support and ideas, which should not be relied upon or implemented in lieu of consulting an A&P or other qualified technician. Aircraft Spruce assumes no responsibility or liability for any issue or problem which may arise from any repair, modification or other work done from this knowledge base. Any product eligibility information provided here is based on general application guides and we recommend always referring to your specific aircraft parts manual, the parts manufacturer or consulting with a qualified mechanic.
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.