Online Community of Zenith Builders and Flyers
Survey: Carbureted Engines - Gascolator and/or Fuel Filter Screen Mesh Size?
Doing an informal survey of operators of carbureted (and carbureted only - not fuel injected!) engines as to the configuration of their fuel filtration systems. I'd like to know:
- Whether you use a gascolator only, gascolator plus inline fuel filter, or fuel filter only and no gascolator.
- Filter type - pleated media or metal mesh screen.
- Filtration ability in microns of gascolator or filter. (BTW, in case you don't know, the typical ACS gascolator that is commonly used comes standard with a 122 micron screen and there is a 74 micron replacement screen available.)
- Whether the carb has an internal final filter screen or not.
- Whether your system is gravity-fed only, gravity-fed plus boost pump, or full-time fuel pump either engine-driven or electric.
John
N750A
Replies to This Discussion
-
Permalink Reply by Michel Ruf on
-
Rotax 912 ULS, gravity feed, gascolator with metal mesh screen size 100 micron only (As in installatio manual of Rotax). No inline filter, no filter in the carbs.
Michel
-
Permalink Reply by Ken Ryan on
-
No argument here, Michel, but a little clarification with regards to the Rotax installation manual. I went to the flyrotax.com website and downloaded the installation manual for the 912ULS. These are direct quotes:
1. Coarse Filter - One per tank as per valid certification
2. Water Separater / Gascolator - The installation of a water separator/gascolator must be carried out by the aircraft or fuselage manufacturer and verified according to the latest regulations, such as FAR or EASA. NOTE A suitable water separator/gascolator must be installed at the lowest point of the
fuel feed line.3. Do not use plastic filters in the engine compartment. Only fire proof or fire resistant material can be used in the engine compartment.
4. Do not use paper filters as they can absorb water.
5. In the feed line from tank to the fuel pumps an additional fine filter with mesh size 0.1 mm
(70–100µ) has to be provided. The filter has to be accessible for service.
A combination of filter/watertrap (gascolator) is recommended.Number 5 seems to indicate that if you have a fuel pump before the gascolator, a filter is required to protect it. As is frequently the case with Rotax documentation, things are not always crystal clear.
-
-
Just tried to answer John's question. Was not intended to blow up my post as Rotax owner already know the manual. But good you provided more info.
Coarse filter is already in the kit and sure helps. The rest in my installation is kept simple as Rotax recommends. Gascolator with mesh 100 Micron, no other filters downstream. Pump after Gascolator at the lowest point (push) to help prevent vapor lock.
-
Permalink Reply by John Austin on
-
And thanks for your answers, Michel! Hope several others will chime-in with their set-ups!
John
-
Permalink Reply by John Burns on
-
Jabiru Gen 4 with just the stock Zenith supplied Gascolator with the original 120-micron screen. No other filter or screen other than the very course finger screen that Zenith provides for the tank. I have the stock mechanical Jabiru fuel pump with a Facet Electric pump for backup. As a 750 STOL the system will gravity feed just fine in level flight. Our fuel flow testing says that gravity alone will not keep the recommended Jabiru full fuel flow at high angles of attack. We wrote the POH and checklist to require the electric fuel pump for takeoff landing and maneuvering flight.
New from Zenith:
Classified listing for buying or selling your Zenith building or flying related stuff...
Custom Instrument Panels
for your Zenith:
Custom instrument panels are now available directly from Zenith Aircraft Company exclusively for Zenith builders and owners. Pre-cut panel, Dynon and Garmin avionics, and more.
Zenith Homecoming Tee:
Flying On Your Own Wings:
A Complete Guide to Understanding Light Airplane Design, by Chris Heintz
Builder & Pilot Supplies:
Transition training:
Aircraft Spruce & Specialty for all your building and pilot supplies!
How to videos from HomebuiltHELP.com
Developed specifically for Zenith builders (by a builder) these videos on DVD are a great help in building your own kit plane by providing practical hands-on construction information. Visit HomebuiltHelp.com for the latest DVD titles.
© 2026 Created by Zenith.Aero.
Powered by
