Gascolator for fuel injected Engines

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Thez

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Jan 31, 2012
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I'am currently building a low wing sport plane and planning on using the UL Power 350i engine. Have been doing a little research and found some points against using a gascolator...Looking for some insight pro/con

Filtering-will have a screen on fuel tank, UL uses coarse filter before fuel pumps and fine filter before injectors

1. Gascolator is another leak source, also since it is on the suction side of the pumps, air could possibly be sucked in causing cavition of the pumps which is worse then any water in them.
2. Increased resistance on pump
3. If gascolator is located on firewall side, engine compartment heat and lower pressure could cause vapor lock potential.
4. If Mogas with Ethynol is used (UL- allows up to 15%), water would be engrained in the fuel.
5. The high volume of returned fuel vs burned fuel causes any possible water to be mixed thoughly with fuel where it would not be noticed by the engine and eliminate and chance of water slug.
6. As with any AP, tanks should be sumped as part of preflight. When a pump is turned on the lines are purged in about 1 second. This could also be used a secondary preflight procedure to resump.

Vans, Airflow Performance (injector manufacturer) and Jan at Viking all don't recommend Gascolators with fuel injected (Think I'm quoting correctly)
Joe
 

rv6ejguy

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We've been doing EFI in aircraft for 19 years and also don't recommend using a gascolator as it serves no useful purpose with a return type fuel system. In Canada, we must have a gascolator unfortunately even though one inspector who recently stated off the record that he realizes they don't do anything. But he didn't see any change in the foolish regulation coming any time soon.
 

Dave Prizio

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Tustin, CA / USA
Many RV builders are now eliminating the gascolator. However, the fuel strainer function of the gascolator needs to be met by some other means such as with a high quality fuel filter. If you have fuel injection the standard fuel injection fuel filter will meet that need.

The fuel system must also be designed so that there is no low point that can collect water between the fuel tank and the engine fuel pump. If you can meet these requirements then it is reasonable to consider eliminating the gascolator, and most DARs should go along with it.
 

Thez

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rv6ejguy,
I've seen on the Van's sight there seems to be a number of guys also not using gascolators and heard Vans doesn't even include one with EFI engine kits, What are you doing for water removal? or is it a none issue with injection?
 

djschwartz

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Portland, Oregon
When I re plumbed my Stephens Akro years ago I put one fuel drain fitting in line at the low point in the fuel system between the tank and the fuel pump inlet. It's simple to do, costs little, and adds no measurable weight. I never found any water in it but it was a nice safety feature to be able to check it. Being a taildragger made the low point more obvious, the pump was behind the pilot's seat, but it should still work fine with a nose wheel.

Dave
 

rv6ejguy

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rv6ejguy,
I've seen on the Van's sight there seems to be a number of guys also not using gascolators and heard Vans doesn't even include one with EFI engine kits, What are you doing for water removal? or is it a none issue with injection?
Water is not an issue with return type EFI systems since the high rate of return mixes any water up with the fuel rather quickly. It simply passes though the engine just like in any modern car. We usually just fit some of the Earls 3 X 1 billet filters with the sintered bronze inserts pre- pump. Cheap, reliable, light and easy to clean or service.
 

Thez

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rv6ejguy,
I am familiar with with Earl's billet filters, not sure what a 3 x 1 is. Couple questions for you on these: Where are you installing the filter (one per tank?) and how often do you unscrew to check them? What micron are you using and is this your only filter in system? I believe these filters are for dirt only, no water. If you had a Earl's number that would be great.
 

Toobuilder

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200HP Lyc in the RV - tank drains are the lowest point in the whole system; big filter in front of the pump; no gascolator.
 

rv6ejguy

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rv6ejguy,
I am familiar with with Earl's billet filters, not sure what a 3 x 1 is. Couple questions for you on these: Where are you installing the filter (one per tank?) and how often do you unscrew to check them? What micron are you using and is this your only filter in system? I believe these filters are for dirt only, no water. If you had a Earl's number that would be great.
We usually use one before each pump only when using impeller type pumps. If you use roller vane pumps, you also want one after the pumps as these types can shed metal when they go bad. 35 micron element Earl's Performance Inline Fuel Filters 230106ERL - SummitRacing.com. I'd inspect the filter initially at 10-20 hours after a new build as there is often some junk in the tanks/ lines. After that, I just do it once a year. Water will go through these I believe which is what we want with EFI anyway, to have the return fuel flow mix everything up so any water in the system is so diluted, it has no effect. Place your quickdrains at low points and check these during preflight.
 
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