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Carb has fuel but no flow

I have a push lawnmower that has transmission control, and blade engage control.

I have checked spark and it’s very strong, compression is low but seems present, fuel flow from the tank, to the cut off, to the carb is ok, carb fills with fuel, but there’s no flow into the chamber. I got it running by adding a cup of 10-30w oil and started due to starting fluid then died, to keep it running I push 1 second bursts into the intake hoping it will start sucking in fuel, it still shows no fuel flow.

I removed the carb and cleaned it, used air to blow the holes clear and reinstalled, still no ignition. The plug is gapped correctly, fuel is super unleaded, oil comes out almost black metal paint color (i an unable to find the drain plug) i added some oil and shows stronger compression. still no ignition

lawn mower is similar to Husqvarna HU725AWD

but the parts are inverted, intake and exhaust are opposite and blade/transmission controls are on the other side of the handle

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Android 维修工具包



Android 维修工具包



2 Answers

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Hey Mike.

To do an oil change, empty the gas tank first. Remove the oil fill cap/dipstick and check the oil level to see if it is overfilled. Your model doesn’t have an oil drain plug, by the way. Position a catch pan on the oil cap side of the mower and tilt the mower over on it’s side (oil fill tube side) and allow the old oil to drain into the pan. Then set the mower back onto all four wheels.

If there was too much oil measured on the dipstick, earlier, remove the spark plug and pull the start cord several times to help evacuate any oil that may be in the cylinder. Clean and inspect the plug, and make sure it’s properly gapped, then reinstall the plug (or a new replacement plug) and reconnect it’s boot. Also, check the air filter and clean or replace as required, at this time.

Carefully add new engine oil in increments, taking care not to overfill, until the correct amount registers on the dipstick. Then cap the oil fill tube.

Add some fresh gas (marine gas would be a better fuel as opposed to “super unleaded”, by the way), and try to start the mower. Allow several attempts, as the fuel likely lost it’s prime during the service just performed.

If you still have a no start result after your fuel supply to the carb is re-established, the carburetor might be varnished – usually caused by leaving fuel in the system for too long. The metering needle, jets, etc., may become clogged or glazed with the old fuel, which tends to become sticky (like varnish) and sneakily alters the prescribed air:fuel mixture. Blowing things out alone won’t likely solve this problem. You’ll either need to thoroughly clean the carb using carb cleaner and fine gauge wire (s), plus compressed air, etc., or the carb may need rebuilding or replacement.

Hope this helps. Good Luck.

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One step at a time: you got it running with starter fluid and then put a cup of “10-30 W” oil in the gas tank? Really? Why? This could aggravate a gum or sludge problem. Did you clean the float needle and it’s passage? If it’s stuck, no gas will get into the float bowl.

Then “still no ignition”. Hmm, you had ignition before when you were running it with starter fluid. Same comment for the spark plug gap. And then you commented that the crank case oil is like black paint. I’m not surprised the compression is low since the rings are probably worn out. And how would adding some good oil to the sludge already in there affect the ignition, that was already working?

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