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DA 100 Carb problems

Old 11-13-2011, 12:31 PM
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wally3185
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Default DA 100 Carb problems

Could not get carb to draw fuel. Took it apart and cleaned it out good. Now I'am getting to much fuel? I have the needels set at L 1-1/4 H 1-5/8. With the throttle closed and just idle trim it still is pushing way to much fuel drip, drip, drip. Any help would be helpful. Thanks Eric
Old 11-13-2011, 12:35 PM
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Tired Old Man
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Default RE: DA 100 Carb problems

If the carb is dripping the metering needle was not installed correctly. It is being held open by the diaphragm or improper adjustment of the needle lever fork. That is ALWAYS the cause of carb dripping fuel when not being choked.
Old 11-13-2011, 12:49 PM
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Default RE: DA 100 Carb problems

OK, thanks for the tip.
Old 11-13-2011, 01:37 PM
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Default RE: DA 100 Carb problems

Make sure the metering diaphragm is against the cover and not the body of the carb. Dan.
Old 11-13-2011, 04:40 PM
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Default RE: DA 100 Carb problems

Make sure you have the fork on the arm engaged into the slot on the button attached to the diaphragm.
Old 11-13-2011, 05:02 PM
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Default RE: DA 100 Carb problems

Most likely the reason for the problem.
Old 11-13-2011, 06:19 PM
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Default RE: DA 100 Carb problems

How long has the engine been running OK when this happened?
Old 11-13-2011, 06:32 PM
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wally3185
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Default RE: DA 100 Carb problems

Bought the engine used, this is my first atempt getting it ready to fly. Engine has good compresion, and the price was right. If all I have to do rebuild the carb or buy a new one I'm still money ahead.
Old 11-13-2011, 06:44 PM
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Default RE: DA 100 Carb problems

Try the rebuild before you do any thing else. It's very easy to do and there is plenty of RCU help from knowledgable members here to ask questions. Dan.
Old 11-13-2011, 07:50 PM
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Default RE: DA 100 Carb problems

The key was the carb had been disassembled. It's quite common for people to err when fitting the diaphragm pin back into the metering fork. When they do carbs always drip because the pin on the diaphragm is sitting on top of the fork, lifting the metering needle all the time. Really hard to tune since they will be running filthy rich. You have to slide the diaphragm onto the fork, usually lifting one end of the diaphragm for sighting to assure proper installation. Then add the cover plate.
Old 11-14-2011, 04:17 AM
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Default RE: DA 100 Carb problems


ORIGINAL: wally3185

Bought the engine used, this is my first atempt getting it ready to fly. Engine has good compresion, and the price was right. If all I have to do rebuild the carb or buy a new one I'm still money ahead.

The easiest way would be to get a new carb from DA to fix both no and extra fuel problem.

But, rebuilding the carb may fix the original no-fuel problem. Just wonder when you disassemble the carb, you noticed that the diagram on the pumping side sticks hard to the carb body, or the tiny metering needle (with a black tip) sticks to its seat. Either can prevent the gas from flowing, and can be fixed via a simple replacement of these parts from a rebuild kit.

Blockage can also happen in some or all passages for gas to enter the venturi. I have seen often this with carbs used for small engines (up to 50cc), but not often for bigger DA85 or 100 ones, in Texas. Those tiny passages can be cleared after the removing of a small cover on the carb body. A new cover can be punch installed.

Hope this helps.

Old 11-14-2011, 03:36 PM
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Default RE: DA 100 Carb problems

if you ever need a new carb its a walbro wt-71 dont get the wt-71-1
Old 11-14-2011, 03:48 PM
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Default RE: DA 100 Carb problems

That would be a WJ-71
Old 11-14-2011, 05:10 PM
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Default RE: DA 100 Carb problems


ORIGINAL: jedijody

That would be a WJ-71

hehe you got me
Old 11-14-2011, 05:18 PM
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Default RE: DA 100 Carb problems

Got to give it to him, he doesn't miss to much..
Old 11-14-2011, 07:00 PM
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Default RE: DA 100 Carb problems

Especially when Jody and I were having a dioscussion about the same part numbers for a different reason earlier today.
Old 11-24-2011, 08:07 PM
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Default RE: DA 100 Carb problems

He we go. I was having problems with my DA 100 carb. Decided to buy a new one and rebuild the one that can on the engine. Got the new gasket set and rebuilt the old carb. Put it on and had the same problem, will not draw fuel. So, I took out the fuel tank to check it out, eveything looks fine. Checked out all the lines for leaks or cracks, they look fine. Took off old carb, swapped out control link stuff, put new carb on. New carb will not draw fuel either. I've been farting around with glow and gas engines for arond twenty years or so. I am baffled as to what he problem is ??
Old 11-24-2011, 08:36 PM
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Default RE: DA 100 Carb problems

Is this a new engine or used? Can you tell us all about the engine as far as if it ever ran good or not at all. Need more imfo too determine what may be wrong. Thanks Capt,n
Old 11-24-2011, 09:18 PM
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Default RE: DA 100 Carb problems

Bought the engine used from a reputable person, and it was built in 2005. Pulled the plugs when I got it and they looked fine. Engine has good compression. I have removed the plugs and listened to he reeds they seen to be doing thier thing? At this point I'm looking at sending it off to DA. Unless tiher is just something I'm not doing right or overlooking
Old 11-24-2011, 09:21 PM
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Default RE: DA 100 Carb problems

There are two covers on the carb. One covers the diaphram and it has already been addressed that the slotted pin on the diaphram has to engage the meetering needle. Also check the needle itself, the tip is rubber and should be pointed with no gouges.

The other side is actually the pump. The cover is held in place with a single large phillips head screw. After removal you will notice two little flappers on the gasket. Actually it is one gasket that seals the edge of the cover and the flapper valve membrane. The flappers have to be positioned over the correct holes and have to be flat against the carb body. I have seen the gasket installed first and then the flapper valve membrane which is backwards. I usually will fill the fuel resivoir with gas ( area around the screen ) then put in the flapper valve membrane, gasket and then cover. This primes the carb so it draws fuel easier.

If your carb will not draw fuel, it is dry, flapper membrane is installed wrong, flapper valves are stuck to the carb body, carb has fuel passages clogged, meetering needle is stuck, choke plate is not installed correctly or low speed needle is closed too much. Eliminate all these and the carb will draw fuel.

If everything is put together correctly and the carb leaks, just buy a new carb. I tried like hell to clean, adjust and filter a DA 50 carb for months before giving up and putting a new carb on. Seems the bore in which the needle resides had worn just enough to allow the needle cock sidways and hang up.
Old 11-24-2011, 09:33 PM
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Default RE: DA 100 Carb problems

Chances are the carb is dry as pointed out if it hadn't run since 2005. The new carb will be dry as well. Take the cover off with the 4 screws and fill it up with gas and put the cover back on, then do the same on the side with the single large screw. That is the side with the diaphragm that pumps the fuel.
Old 11-25-2011, 01:22 AM
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Default RE: DA 100 Carb problems


ORIGINAL: Super08

Chances are the carb is dry as pointed out if it hadn't run since 2005. The new carb will be dry as well. Take the cover off with the 4 screws and fill it up with gas and put the cover back on, then do the same on the side with the single large screw. That is the side with the diaphragm that pumps the fuel.

double check fuel line.... blow through vent line and fuel should come out of line going to the carb........ look at reed valves?
Old 11-25-2011, 04:34 AM
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Default RE: DA 100 Carb problems

Is your choke closed completely?
On several engines following rebuild, I filled the demand regulator chamber, this was accomplished by pressing down the diaphragm with a small allen key through the vent hole while proping. If the pop off pressure is high, the fuel pump cannot over come the pop off. I actually could hear the air vent once the diaphragm was pressed down.
Can you rig your fuel can to the carb to provide positive presure if you suspect a tank issue?
If you been doing this for 20 years you surely know what's right and wrong, thats why I would suggest depressing the diaphragm.
Old 11-25-2011, 06:05 AM
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Default RE: DA 100 Carb problems

Things to check:
Is your clunk filter in the tank totally clogged? Blow into tank vent and see if your ears pop.
Is the pulse port on the engine lined up with the hole in the gasket and pulse port on the carb?
Is the pulse port clogged with anything like gasket sealant?
Are your reed valves cracked or badly chipped or not closing?
Old 11-25-2011, 06:28 AM
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wally3185
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Default RE: DA 100 Carb problems

The carb I have on now is the new one from DA. I did check to make the sure fork and diafram are hooked up. The back side cover has four screws, I took it off to make sure that the gasket and flapper is correct. There is no screen that I could see. The fact that it is dry makes sence. My idea is to force a prime by putting some pressure in the tank while pulling it thourgh. Going to try that today when I get a chance. Thanks for all the help and advice.

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