Gascolators in Fuel Injection Systems

andrewbutler · #1 09-05-2008, 05:40 AM

Hello,

Can someone help me understand why a Gascolator shouldn't be used in a fuel injection fuel system? I am installing an IO360 XP Superior in my RV7 in a few months. Some time back, I came across a FI Fuel System schematic from Titan that had a Gascolator included, so earlier this year I went and bought an Andir Gascolator with my Firewall forward kit. Digging deeper, I can't see any further references to such a set up. Was is a waste of $160?

Best regards,
Andrew Butler,
RV7100,
Galway, Ireland.

pierre smith · #2 09-05-2008, 05:44 AM

.....not a waste, Andrew,
We're building a -7A with a Lycoming IO-360 and it'll have a gascolator as well. If it's rated for the pressure, you're good to go. A lot of guys on here poo-poo a gascolator on FI engines but my question is, "Where does the trash and water collect then?" I've seen both on an IO-520 Conti on an Agwagon in the past.

Regards,

Kahuna · #3 09-05-2008, 05:51 AM

A search for gascolators will yield much discussion and debate on this topic for you.

David-aviator · #4 09-05-2008, 07:30 AM

I used a gascolator with the Subaru installation but it was before the fuel pumps just after the fuel valve. Over a 4 year period of checking it periodically, no appreciable amount of dirt was found and no water was ever found.

As I proceed with the Lycoming installation, the gascolator is out of the picture. It will be AFP in line filter only. I have not decided where to place it in the system, before or after pumps, but there will be no gascolator.

frankh · #5 09-05-2008, 07:48 AM

Absolutely nothing wrong with a gascolator on a FI system..Almost fitted one myself. There is no difference between a FI and carbed system..If your going to fit one to a carb'd airplane then the same argument is there to fit one to a FI system.

It is at the low point in the system and would be your last line of defense if you had water in your fuel...Hmm as Im now running 10% ethanol maybe i should have fitted one..but I digress..

BUUUT...330 hours (airplane mostly in a hangar) of IFR rain flying etc has not shown any problems, in fact I have yet to see a single drop of water in my main tank drains so I'm comfortable without it.

But I would also be comfortable in NOT putting one on a carb's motor for the same reasons.

Frank

w1curtis · #6 09-05-2008, 08:23 AM

The question should not be "gascolator for fuel injection systems" but "gascolator for low wing aircraft."

Gascolators are typically used in high wing aircraft because when the aircraft is sitting, if there is water in the tanks, water being heavier than gasoline will flow to the lowest point. In a high wing aircraft the lowest point in the fuel system will be below the tank drains in the fuel lines so just draining the wing tanks will not remove water from the system. A gascolator in high wing aircraft allows the draining of water in the system that is already lower than the wing tank drains.

In a low wing system however, the fuel tanks are at the LOWEST position in the system so any water in the tanks can be removed by the tank drains. A gascolator on the firewall in a low wing aircraft should never have any water in it from the aircraft just sitting. Additional, a gascolator will not stop water that is being force by the pumping action since the flow will not allow it to settle. For this reason a gascolator on a aircraft with the engine higher than the lowest point (fuel plumbing that goes "up-hill") of the tank is useless. As for filtering, you already have the Airflow filter before the electric fuel pump.

For those that have gascolators on RVs--have you ever found any water in them on draining? If so, you have found a new secret to flight, water that can defy gravity.

rv7guy2 · #7 09-05-2008, 09:00 AM

Gasolators are MANDATORY on amateur builds here in Canada. At least here in South Western Ontario. The MDRA inspectors insist on them and will not pass an inspection without one. I installed mine as per the Van's drawings for a carb engine and my 10-360 runs like a charm. No problems at all. And it gies me, that one extra fuel check before I fire up and turn hard earned cash into exhaust vapour.

Dave
RV-7
C-GCPD

rv6ejguy · #8 09-05-2008, 09:18 AM

On FI systems with return fuel flow, they are of little or no value as the return fuel flow may exceed a gallon per minute. Any water is thoroughly mixed up with the fuel due to this recirculation.

On returnless systems, they may have some value, depending on where they are placed in the system. Gascolators placed under high pressure are not of much value.

Quick drains at all low points work fine and are highly recommended.

In short, won't hurt other than more plumbing and more money but may not be of any benefit either. Check your local requirements.

In my view the Canadian regs don't make sense for all FI applications but they cover everyone the same way regardless of system because they don't understand some of these systems and how they work. Proper filters are far more important here but I've never seen them checked for.

rtry9a · #9 09-05-2008, 10:00 AM

Im guessing that gascolators add little value when mogas is used or anywhere a bit of ethanol is added to fuel- the alcohol scavenges the water and holds it until its burned. Comments?

RickWoodall · #10 09-05-2008, 02:43 PM

What i am planning due to regs in Canada and AFP discussions, is one gascolator on each wing root as low as i can, hard plumbed to outside of fues. Then, a flex line from gascolator to fuel line. On a 9 thats not easy but seems to be worth the trouble, i am not sold on mounting it Fwfwd on FI. Would really like to see more pics if other have done it this way, or criticism if this is dumb