Hedge trimmer , mod.040090D 40350. Won,t start.. I pulled the plug, grounded the plug body, a spark should be seen at the plug gap., but instead a spark is seen from the plug body to ground, what would cause this

You need to make sure you have spark. Remove plug, connect spark plug wire, hold plug to motor to make ground. Pull recoil and take note if you have a blue spark on the electrode of the spark plug. If you do, then it is a fuel issue, most likely gummed up the carb. Try carb cleaner spray and fresh gas.

Two items fairly easy to check; the condition of the spark plug and whether the ignition coil is healthy. The plug must be removed to check it for fouling (a buildup of deposits near the spark gap) and also wipe the insulator of the plug clean and inspect it carefully for fine lines; a cracked insulator (not uncommon) will provide a path for the spark voltage to ground before it reaches the spark gap. The ignition coil can be checked by sight in a shady area (sunlight makes it tough to see). Pull the plug wire free of the plug and insert anything metallic into the female connector that will extend the contact. Position your extension near some metal part of the engine and watch this gap as you tug on the starter rope. You should be able to see the spark appear a couple of times with each pull of the rope to its limit.
These coils are not very well made and cost $30-40 US to replace.
Once you have access to the coil. use some gauge (could be a knife or screw driver blade) so you can re-gap the coil if a new one is installed.
I suggest that you go to the Sears website below and enter your model number. You should find it listed there and it will have a parts breakdown of your trimmer along with part numbers, etc.:

Sears parts dept.

Using this you can orient yourself on the innards of the trimmer.

could be the air filter needs replacing

GAP ON THE COIL ? USE A MATCH BOOK COVER. SPARK PLUG FOLD THE MATCH BOOK

clean spark plug and gap, remove air filter and clean, look at the spark plug and tell us what color it is, You may need to adjust the fuel mis to get it to run right or you may need a gas filter. Post here with more information.

Do you have fresh gas? If so is the mix right? If you can get to the carb easy spray some carb and choke cleaner in it. Check the gap on the new spark plug. The gap should be located somewhere in the manual. The big problem is making sure that the mix is right. To much oil in gas will foul plug smoke like crazy and foul the plug and hard to start. Not enough oil and you can seize it up.

Good luck let me know if this helps.

roundo4

need to gap plug correct

Remove spark plug from the engine, reconnect it to the plug cap cable which come from the bobin.

Find a piece of steel wire jumper, atleast a foot. Make a jump from the metal body of the plug to the chassis of the engine.

Safety issue: Place the plug away from the spark plug's hole on top of the engine to avoid gas ignite.

Set the trimmer on the floor, set the gap of the spark where visibility while you pull the string.

Pull the start string and the arc could be seen right on the plug gap. Consider an Arc Purple or Blue coloration are good.

If the arc has not been seen, the Magneto need to be serviced.

No. Sounds like the crankcase is filled with fuel.

remove plug and ground and see if you have spark at electrode.

Sometimes will not fire under compression.

Check that kill switch is not shorted, just remove the wire going to ground and try again.
If not probably bad coil.
Joe