Gas Engine Help

I have a DL50 that probably has 5 or 6 gallons through it. Love the engine. Runs great and strong. Normally easy to start.

I have a problem I now think may be related to dirty fuel. Some points.

Fuel mixed in jerry jug maybe 5 months ago. Redline synthetic 50 to 1.
Ran plane for an afternoon of flying. Ran great, no issues. Next day out, maybe 3 days later, I noticed fuel coming from the carb while filling the tank. Never noticed this before. She was floaded when I went to start or on the stand. Ignition off, full throttle, several flips to clear her out and then she started and ran great.

Next day out, maybe 2 days later. Same floading issue. Take plug out and she tries to fire up on first flip, but does not run. Flips after that have no result. Take plug out again, same thing on first flip, nothing after.

Take carb apart, blow out with air. Notice some small black particle come out into cloth used to hold carb. Reassemble. She will start on first flip and run. Adjusted high and low needles. Shut off. Will not restart. Take plug out. Starts on first flip. Repeated for pattern. If first flip starts her fine, she runs. If not, she will not start and other flips do nothing.

Take carb off again. Blow out. Notice some of the gasket starting to flake off. Change diaphragm, gaskets, fuel hose, tank. Change fuel set up from 2 line system; vent and line to engine with “T” for filling. New system is 3 line system, vent, straight to engine and fill line. Change fuel in jug, and fueling hoses. Filter old fuel thru coffee filter and find particles. Filter new fuel through coffee filter and mix in oil.

Fuel jug has filter down stream from pump. Plane has fuel filter in fill line.

Reassemble. Engine starts on first flip and runs. Low end needed to be only about ½ turn out to get rid of gurgle except at idle. Ran well. At first was able to get her to restart if she did not start on first flip. But again had problems if not started within a few flips. Would need to take out plug, not wet, then start on first flip.

Head temps seem normal; around 200. 300 and change by muffler.

It seems the low needle is turned in a lot from factory settings. Run near sea level in 90 degree heat, with humidity near the temperature (Abaco Bahamas).


Any suggestions on what I could do? Perhaps soak carb in carb cleaner? Pass small wire thru jets? B Does this sound like a dirty fuel problem?

Any help would be appreciated.

Fuel dripping from the carb means that the internal needle valve (diaphragm operated) does not close. Reason can be a dirty valve tip, or the lever is set too high. The rich idle mixture points in that direction. If the lever has a forked end, be sure the fork engages with the slot in the diaphragm boss. (same effect as lever too high).
Clean the valve tip and valve seat. Carfully! The rubber tip is easily damaged. A toothpick will do for the seat. Rotate with a bit of thick oil, so all debris will adhere to the pick.
Check the lever. It should be about horizontal the moment the valve lifts.
check the gaskets! The lever diaphragm must have the gasket next to the carb body, the pump flapper has the gasket next to the flapper cover.

Do you have a buddy with a DL50-55 that you can borrow the carb from? How did the metering lever look in the carb? Does your ignition/plug test out well? If you do have a friend with one, it's nice to swap ignitions and carbs to quickly narrow things down.

Thank you for your help. Just an update, and some thank yous. I used carb cleaner and blew out the card again. Used heavy oil on a tooth pick. More carb cleaner. Re assembled and all is well. Running like a DL50 again. And we are all here taking a bit more care in filtering our fuel.

I used coffee filters to filter the fuel into my field jug. Any suggestions on a better way would be welcomed.

Loving the help on RCU

Use a Chamois

Very cool idea. Natural fibers. I will give it a try. Thank you.

Fuel cleanliness is an absolute necessity. I am glad you solved your problem.

Yes. For sure. Learned my lesson. Back in the day we used to get our glow fuel from another island, which stored it used 55 gallons drums. There was never a question but to strain the fuel. I will go back to those good practices. I appreciate you so generously sharing your knowledge. Thank you all for your time.

One of these in the fuel can and one in the gas tank and you won't have anything contaminating your gas again. Change them once every year or two.

I heard this recommendation from you then Jody....and a few other seasoned gas engine people recently. I now use these as my clunks. My local hobby store stocks/sells them for only $2. I was amazed. I also use a final filter before the carb. My Jersey fueler gas can has a ceramic clunk and then one of those see-through gas filters. I have 4 filters between the gas pump and the carb. I think that's enough.

I just use the felt clunk in my fueling line, and the clunk in the tank. Of course NO T-fill line.
I used to have an extra paper gas filter element in my aboard fill system line, but that is over a year ago now. When working on my carb last week checking pop-off etc., the internal carb filter was clean after a full season of use.

I also do not have a T in my supply line to the carb. I use a felt clunk for the carb supply line. I use a regular heavy clunk for the fill/drain line. I think in the future I might not use a clunk in the fill/drain line and just bend some brass tubing down into the tank...sort of like the vent line but bent down. I'll still have three holes in the stopper, just one clunk. Except getting that into the tank might be tricky. Probably would have to twist the fill/drain tube up to get it in...then twist it down after the stopper is on.