FUEL PROBLEM

flyer · Post by **flyer** » Fri Jan 05, 2007 3:08 pm

1985 M-5 180C. During the last few flights, I have noticed a left wing heavy condition develop. When I checked the fuel on the ground, I found that the left main fuel tank had not used much fuel. The right tank had used about 6 to 8 gal.

The temperature has been below freezing for quite some time and only occasionally gets above 32 F.

Has anyone had this problem? What are the possible causes, ways to check for them, and ways to fix them?

Thanks

flyer

Hottshot · Post by **Hottshot** » Fri Jan 05, 2007 3:33 pm

#1 are you usein' the Both setting on the Fuel selector?

Need a little more info.....

donknee · Post by **donknee** » Fri Jan 05, 2007 3:55 pm

Flyer- Wup is on the right track...you need some more information to acquire a solution. In "maintenance" there is a thread on some things you might want to review as it covers a variety of issues, this will get you close: http://www.maulepilots.org/forums/viewt ... c&start=15

What would tell more information, too...is if the engine will draw fuel from the "left" selected tank. Then you could eliminate frozen water, plugged fuel line, etc. Were you doing a lot of circling to the left, photos, scouting for game? Are the vents clear?

flyer · Post by **flyer** » Fri Jan 05, 2007 4:57 pm

I forgot to include that I have BOTH selected. This imbalance is a new problem. I flew all summer with no imbalance or uneven fuel useage.

I check the fuel when I land and it is out of balance. The next morning when I check the fuel levels, they are even.

It seems that the problem may be in the fuel selector valve. If that is the problem, why do the tanks level themselves overnight?

I also thought it might be some ice blockage but that does not make a lot of sense.

The right tank is where the fuel is being used. The left wing becomes heavy.

It is a mystery.

Flyer

Hottshot · Post by **Hottshot** » Fri Jan 05, 2007 5:04 pm

The fuel levels will siphon at night and even out whe you let it sit in the both setting. as for why it is going un-even in flight there is a reason but it esczpes me at the moment. I will search and get back to you ASAP. or Jeremy will get back to you.

maules.com · Post by **maules.com** » Fri Jan 05, 2007 6:08 pm

Flyer, follow the link placed by donknee above. There is a little more to that q and a but I won't write of it right now, it's beer time.

g5280 · Post by **g5280** » Fri Jan 05, 2007 7:19 pm

Flyer,
Jeremy told me some years ago that to fill up the main tanks on my 87 M5 235 it is best to put your fuel selector on rite or left leaving it on both will allow the fuel to drain back and fourth. I think that should solve morning fuel equally distributed mystery.

flyer · Post by **flyer** » Fri Jan 05, 2007 7:56 pm

g5280

Thanks for the response. The problem is not the tanks equalizing. I want them to be equal. The question is why has the fuel tank useage changed with the fuel selector still in Both. In the summer the fuel appeared to feed equally. Now the right tank feeds significantly more than the left in flight and then equalizes on the ground. Fuel Selector always on BOTH.

Thanks

flyer

g5280 · Post by **g5280** » Sat Jan 06, 2007 12:54 pm

Flyer
Back to what donknee pointed out http://www.maulepilots.org/forums/viewt ... c&start=15 READ THIS Jeremy explains your exact mystery. If it still doesn’t make since we will ask him to explain it again

flyer · Post by **flyer** » Sat Jan 06, 2007 3:34 pm

g5280

I have read those postings before. I discounted them since I flew all summer without this problem.

In the winter I fly when the weather permits to keep the engine active. I do not like it sitting all winter.

In the winter I fly very light and slower since I am not really traveling far.The difference may be that at the slower speeds and lower power settings a yaw may be created that is different than when I fly in the summer.

I am burning more fuel out of the right tank. That is opposite than the problem in the posting.

Flyer

Gene · Post by **Gene** » Sat Jan 06, 2007 4:19 pm

Stab in the dark, but you may want to verify your tank venting. Remove the tank caps. Take a plastic hose and gently blow into the 3/8" vent line behind the strut. It should not require much pressure. Verify both side are in same position behind strut. Good Luck!

flyer · Post by **flyer** » Sat Jan 06, 2007 4:55 pm

Gene

Thanks for your input. A clogged vent line could cause this problem. I checked both of them and there seems to be no restriction.

flyer

donknee · Post by **donknee** » Sat Jan 06, 2007 5:57 pm

Flyer- It sounds like you are going through all the possiblities rather thoroughly. You might check to see if you get enough fuel flow on the LEFT tank to run the engine at full power...just for a safety issue, if you need to run on the LEFT tank. It could be a partial obstruction in the fuel line from water/mung/etc. You can check your fuel flow gauge on LEFT and RIGHT tanks, too....just to mine a little more data. If you can get it into a heated hangar for overnight, drain some fuel to satisfy you have clean lines...you can eliminate the frozen obstruction. If you have to get down to nuts and bolts...you want to know where to start. I seldom fly on BOTH, so I don't know about these characteristics.

flyer · Post by **flyer** » Sat Jan 06, 2007 6:30 pm

Donknee

Thanks for the suggestions. As soon as the snow on my runway is down to a useable depth, I will try full power on the left tank. I have flown with the selector in Both all of the time.

Do most of you fly with your fuel selector in Both?

Has anyone else had similar problems?

Thanks

flyer

maules.com · Post by **maules.com** » Sat Jan 06, 2007 10:53 pm

To check your fuel access from the two separate tanks, on 'both', note the fuel pressure, then switch to your right tank and run for a few minutes and note any fuel pressure change, then switch to left tank and again note the pressure. This is best done at cruise power and level (not climbing or descending), the pressure should be approx 4.5 on all settings, or at least the same on all.
If you fuel up your plane with the selector on 'both', then by the time the gas attendant closes the first tank, comes down the ladder, moves the hose and ladder, climbs back up, undoes the cap and fills the tank, some gallons can move from the first tank to the second and you will not have full tanks.
Always move the selector to 'left' or 'right' before refuelling and when leaving the plane parked with full mains.
If one tyre is softer or an oleo weaker or the ground is not level, then fuel will transfer from higher side to lower side if the selector is in 'Both' or 'Off'.
It is adviseable for the most accurate determination of fuel remaining to fly on 'Left' or 'Right', Except, when landing or takeing off or performing slip maneouvers with Low fuel.