Mac ms1635av wont start i have spark and gas, plug looks good, what next?

Try spraying carb cleaner inside the carburetor. Left over gas will clog the tiny ports inside the carburetor. Next time either add stabilizer in your gas tank or run it dry until next season. Good luck!

hi craig first of have you changed the spark plug ? it may look good but might be breaking down inside was it running then stopd or has it been stored >

Check your spark plug to see if it is fouled out see if it is dirty with carbon deposits white discolored or tan looking also check to see if the plugs are wet with gas or oil if everything looks good and you don't smell a high content of gas the next thing you could do is compression check and or check intake valves

What did the spark plug look like when you first took it out? Was it black/wet/sooty or was it a light tan/gray color. If it was black/sooty, then I would guess you need a coil. I know you said it had a good blue spark when you checked it, but if you poured a little bit of gas in the cylinder and it still wouldn't fire that would be my first place to check. If it ran briefly after you poured a bit of gas in the cylinder and then died, then it's a fuel supply issue. Remove the line that goes from the gas tank to the carb and make sure you have gas at the carb. If you have gas, then I would remove the carburator and take it apart making sure all the jets and passageways are clear. Use carb cleaner and an air attachment and if you still can't get it out, use a small wire to clear things up.

Reassemble and it should run, otherwise report back and we can go to the next step.

spark plugs are deep in the head yet you should get all the the old fuel out first, stale fuel wont ignite and will also clogg fuel filter. you need a mix of atleast 70% new fuel even then its not good for the injecters. If its a manual gearbox a tow start is a quick fix although no go for auto's. cant be much wrong if car was fine when parked, plugs-fuel-filter and possibly fuel pump for sure. If that doesnt fix take plug out put in lead and crank engine to be sure you have spark even just put any plug you know works in lead leaving your plugs in engine just to check for spark y turning over engine looking for spark on plug good spark will be blue but any spark is good.

Check for spark at the plugs and check the fuel pressure. Also remove the spark plugs and check for fouled or wet plugs. A plug that is saturated with gas will not spark. Clean the plugs and dry them off and try to start. If all looks good then check cylinder compression to check for a blown head gasket.

Check to see if the plugs get spark next.
If no spark look for a bad ground somewhere along or around the coil area.

This will be a good place for you to look:
http://carburetor-manual.com/mcculloch-chain-parts-manual-ms1635av-ms1838av-p-1078.html
Copy and paste the URL into your browser and check out the downloadable instructions for the saw.
Paul

Only three possiblities. no gas, no spark, or the timing of the 2. So first follow the full lines and disconnect and turn on the ignition. That will start the full pump. you should see gas flow. Next remove a plug wire and dont hold it but place it near a plug or anything metal on the engine. You should see a spark when cranking the car. Finally its the timming of the two. remove spark plug from number 1 cylinder, with a wrench turn the crank shaft around untill the cylinder comes to top dead center. Look through the spark plug hole you should see the piston top. Now take off the distrbuter cap and look to see which terminal the rotor is touching. follow the wire and make sure it is the same wire that goes to the number 1 cylinder. Of course if the distributor rotor isnt rotating then of course your timing belt is broke. Good Luck.

It is good that you have spark. That means that it is probably not an ignition problem.

Next best bet is to check if your fuel system is working correctly.

Next I would suspect the fuel pump or fuel pump relay.

It will probably help if you buy a haynes manual for your vehicle and follow the troubleshooting steps.

It is hard to go through all of the steps through this system.

Good luck. I hope that it is an easy fix.

Tim