DA 150 has me puzzled

[Shawn Berkheimer]

OK here's the deal, My DA 150 has been running great. I flew all weekend with it at the SW regionals and it was running like a top. After the contest I pumped the tank completly dry and there she has sat for 4 weeks. Today I packed up and went to go fly. the engine was a no go. I could see that fuel was not getting pumped to the carb. I pulled the carb off and checked the screen, checked my in line filter, checked to see that the diaphram pin was properly engaged, replaced all the lines and I still have the same problem. the carb just won't draw fuel. Has anyone else had this issue after letting the engine sit for a while? my thinking is that the gas in the carb evaporated, leaving the oil behind and that is now blocking a passage. The screen and the inline filter were clean with no debris at all.

Shawn

[torquen]

Iv left fuel in my carbs, ran the fuel out of the carbs, pulled the full out of the tank and also left it in for several months at a time and my engines dont know the difference. Try cleaning out your entire carbs with gas and a little air pressure.
Garrett

[excelpoint]

Its possible that the diaphram in the carb may have dried out. Dry diaphrams dont draw fuel well. Try pumping some fuel direct into the carb to wet it up a bit, might help.

[TheTank]

I second Excels opinion, try to prime it (the carb) manually by squirting a little fuel in there. Re-attach the lines and see if it will draw, just make sure your choke is all the way closed.

[sweetpea]

And its not a tank problem? Can you draw fuel out of the tank?

Or how about this.......Did you make sure your tank had fuel in it?

[Freddy Warbird]

How are the flapper valves in the pump section of the carb. If they are sticking to the case, I don't think fuel can flow. This is the pump section of the carb. The diaphram is the actual fuel pump. This is a pic of a Walbro 32 and a 31, but the fundamentals are the same. In the exploded view part number 20 is the pump. What carb is in the 150 by the way?

[Vic3D]

When you dried out your motor last time you ran it (mistake) you took all the fuel out of the carb and the diaphragm dried up and it's pumping very little fuel. You need a carb rebuild kit available at any garden shop, and just replace the diaphragm and you should be ready to go. Replace the flapper valves(included in carb rebuild kit) on the other side of the carb too.

Vic

[Shawn Berkheimer]

The Diaphram and the flapper valves are all in good shape and very pliable. when i got home and took the carb apart it was full of gas so it appears that fuel is getting to the carb but maybe not through the passages leading into the venturi. My thought now is that when the gas in the carb evaporated, the oil was left behind and that may be what is cloging something. In the 8 years I have been running gassers I have not had this issue.

Vic, the engine was not run dry, I simply emptied the tank. Usually i will leave 1/4" of gas in the tank just to make sure the fuel pickup line remains pliable. Even so, all engines are shipped without fuel in the carb and 99.9% of them fire up and run just fine.

Tomorrow I will run some carb cleaner through it ( Spray can with a straw ) re-assemble, check my throttle settings and try again.

As a side note I finished repairing my Dad's 260 QB. the 100 on it had been sitting for 3 months and fired right up. Put 3 flights on it without even as much as a gurgle.

Shawn

[jongurley]

I would replace the diaphram anyway just to make sure, go and buy a carb rebuild kit from your local lawnmower shop, it will take 20 minutes tops to rebuild it,,, it doesn't hurt to do this every year or so anyway,

[TimDavie]

Was your carb dry when you took apart to check? if completely dry, i would suspect a pumping problem. the only other thing to check that you haven't mentioned, is if the carb is snugged up, and not allowing an air leak. You said you checked the pump flap and it was supple. If the carb is wet on the pump side, but not on the diaphragm, fuel is not making it through the metering pin. If the carb is totally wet and the jets aren't clogged, does ignition has good spark? anyway, we are all interested to know what happens.

[wmat7039]

Shawn.... In my opinion: Depending on what oil you use in the gas, it could tend to stick the inlet valve inside the carb. This has happened to me before on a G-62..... Try taking off the cover plate & also the diaphram...then unscrew the screw holding the spring for the inlet valve on that side.... pull out the valve & look on the rubber tip to see if it's deteriorated at all or feels "gummy".... It may be that is where your problem lies.
Wayne
Sew Busy
http://www.sewbusy.com

[Freddy Warbird]

	Quote:
	Shawn:The Diaphram and the flapper valves are all in good shape and very pliable.

Yep, this is strange.

	Quote:
	Shawn:Tomorrow I will run some carb cleaner through it ( Spray can with a straw ) re-assemble, check my throttle settings and try again.

Good idea, but as said in an earlier post, Blast some compressed air through all the passage ways. Just be carful. keep the air pressure down to about 30 psi, and keep your fingers away from where the air exits the passage ways.

[JoeAirPort]

This happens to my DA50 after it sits for a few months or more. I usually blow in the vent line and flip the prop, that has worked. Also you can plug up the vent and pump pressure into the tank with a fuel filler. Then flip the prop. It starts to draw fuel after a few flips. Works every time on mine.

[GremlinX]

Put your palm over the carb and seal it up. Flip it or rock it. The carb just lost its prime.

[Barney Liftoff]

I the past I have struck the body of the carburetor with something like the handle of a heavy screwdriver. The plane would then usually run for the rest of the day. If you have changed the type of oil you use then there is a possibility of a oil residue causing the needle (of the needle and seat) to become stuck. A slight misalignment between the actuating fork and the head of the seat can also cause this. The only parts that move in the carb. are the fuel pump diaphgram, the needle and seat diaphragm, the fork and the needle. Try it. you have nothing to lose. If it works IMO buy a new carb as they are not expensive. Good Luck.