I have a Sears Craftsman chainsaw that won't start after I put in a new carb kit, fuel lines, primer bulb, air filter, spark plug, and fuel filter.

Any suggestions?

 

Craftsman saw are really made by Poulan. Keep that in mind next time you need parts.
Checked to see if your getting a spark?
Tryed starter fluid?

 

I Ihave checked for spark and it does have it but it still won't start. I havn't tried starter fluid because periodically if I pull on it long enough, I can get it to run and then it speeds up and dies.

 

Did you get the diaphragms in the right place, right side up, on the correct side of the gaskets? If not, this can happen.

 

Ok thanks for the suggestions. I will check that today.

 

Have you done a compression test on it ?? If it doesnt read 90 psi or better it probably isnt going to start.

 

Becareful using starter fluid on this saw to start, it will dry the cylinder out and cause damage to cylinder and or piston. NO LUBE,,,,LOCK UP!! starter fluid WILL take off or out the LUBE!

 

I found in the carburetor that the needle was not set properly. I readjusted it and put a bit of silicone spray on it because it wasn't moving freely. Anyways, got the carb put back together and tried it out. It only runs on choke now and I have been messing with the adjusting screws and seemed to be getting somewhere on the adjustments and then it died but won't start again. It seems as though there is a problem that when it heats up, it won't restart and then it has to sit and cool off before it will start again. I checked for spark and it still has spark and the fuel is still floeing through the fuel line.
Any suggestions?

 

While it is running spray/dribble some carb/brake parts cleaner behind the carb and along all the mating surfaces, if the engine tempo changes you have an air leak and can take the appropriate action. Have a good one. Geo

 

Thanks for the suggestion. I will test that method out tomorrow.

 

x2 on checking for vacuum leak. I had a blower engine that died on full throttle and sure enough, it was a little air leak around the carb. Geo actually recommended that one, too.

 

Right now, I am in the process of replacing the gasket between the intake boot and the cylinder intake hole. I have already replaced the gasket right behind the carburetor where the surface of the carburetor meets the intake boot. I will post later tonight if I have any luck after testing it and seeing how it runs after I replace the intake boot gasket.

 

I changed the gasket between the intake boot and the cylinder. I did a compression test on it and got 120 psi. Up to this point, I have replaced the gaskets between the carb and intake boot, replaced the fuel lines, fuel filter, new fuel tank cap, new air filter, and new spark plug.

It still won't start. Any other suggestions of things to try?

 

Did you by chance check screen in carburetor to see if fuel WILL pass through it? If ethanol has been used in that saw the ethanol will plug up that screen, even though it looks clean try getting gas to go through the screen.

 

Did you by chance block the pulse port hole when you replaced the gaskets. Have a good one. Geo

 

I took the carb apart and put a complete rebuild kit in and replaced the screen. I was thinking that there might be some carbon that is blocking the spark arrestor in the muffler. I was going to check that tomorrow if I get a chance. I will post a note on this thread if checking the muffler shows anything that might be blocking the spark screen.

 

I've had saws do that in the past and turned out the gas lines were deteriorated and had tiny cracks in the bends so it would suck air and needed the choke on to keep running. If the saw is over a few years old, I'd change those lines out. Pretty easy job, fixed mine instantly.

 

I don't think that the fuel lines are the culprit because I just replaced them and put a new primer bulb in.

 

Make sure you plumbed the fuel lines right. The carb pulls fuel through the fuel filter into the carb, the other line goes from carb to primer bulb, primer bulb pulls fuel through carb and returns it to fuel tank.

 

The first time I started the saw, it wasn't connected properly so I switched them around and it ran for about 5 minutes and ever since that, have not been able to get it to fire for a couple revolutions. I have checked the fuel in the tank and the filter is completely covered by fuel but the next thing I will check is the spark arrestor and see if it is plugged up with carbon. From these symptoms, it sounds like there might be some carbon clogging it because it seemed off how it ran great after I switched the fuel lines and then, I turned it off to get some fuel and it won't start. It's like there is a piece of carbon in the exhaust port that loosened from sitting so long (prior to me receiving this saw for repair, it had been sitting in its case for 6+ years and the fuel lines had rotted out). I will have some time this afternoon to work on it so once I check out the spark arrestor, I will try it out and post an update later tonight.


Thank you to everybody for commenting with different ideas!

 

By any chance, does anyone know the air gap between the coil and the magnets on the flywheel? The air gap may be too large causing it to not get sense the magnet going past the coil.

 

If it ran good when the lines were switched, then apparently it was picking up fuel from the line with no filter, which could mean the screen in the carb is clogged again.

 

I read through most all of the replies, a lot of things have been covered.
For your question on the air-gap between the flywheel and pick-up coil, use a dollar bill. Make sure there is no rust on the flywheel or pickup coil ends. Also. unless the pick up coil has been moved, or removed, there should be no need for adjustment here. Remove the plug, rotate the flywheel until the magnets are under the pick-up coil, place a dollar bill between the two (flywheel and pick-up coil) loosen the two screws and set the pick-up coil too where there is slight drag. Tighten the screws, remove the Dollar Bill and send it too me .
........for SAFETY REMOVE THE CHAIN WHILE DOING THE FOLLOWING...........
To check for spark while pulling to start and short period while tuning, take a clear flexible hose about 1/4" or 3/16" inside dia. cut a piece about one and a half inches long. Find a Wire clothes Hanger and cut a section of wire from it about one and a half inch long, (maybe a bit longer) take the wire, and using needle nose pliers, bend a real small loop in the wire at one end. when you get it right, the loop will be barely nudged into one end of the hose and at the other end of the hose the wire will end about half an inch up inside the tube. Slide the wire inside the plastic hose, with the loop sticking out of one end, plug that end into the spark plug wire boot, slide the other end over the spark plug and leave about 1/4" or so of a gap between the wire and the spark plug end.
You can install the plug, or just fix it to the cooling fins (for ground) and with the switch in run position, give the cord a pull while watching inside the tube for a spark. The spark should be BLUE and regular... if it is orange or red, try again with a good pull on the cord, if the same, try moving the pickup coil a bit closer..... you have spark ? good, install the plug, and move to next... No spark? check the plug wire to see if it is being pinched and grounded somewhere, also check the wiring at the kill switch, make sure everything is hooked up properly, and not grounding where it shouldnt. I am going to guess you will have a good spark since previous you stated it will run for short burst, speed up then die.
Now to your Actual problem... lack of fuel... ( and for future reference, NEVER purchase a 2-stroke unit that has a Primer Bulb)
Earlier, geogrubb asked a Very good question...geogrubb
Did you by chance block the pulse port hole when you replaced the gaskets. Have a good one. Geo....
a very valid point and common mistake that can cause the situation you described.... starving for fuel... also a vacuum leak, or a blockage in the fuel pickup system, or carb. can do the same.
Here is a URL to help you with the Fuel Line Routing...
How to Replace Fuel Lines on 2-Cycle Engines : eReplacementParts.com
Now your Fuel Lines are correct, and you have spark, you stated you have 120 psi compression (new chainsaw?) this still leaves Vacuum Leak, or fuel mixing/carb.
Your next easiest step.
Normally one of the first things I do when looking into 2-stroke problems is remove the muffler and work the piston up and down slowly while looking at it through the exhaust port to check for Any wear or scratches. If the engine has cylinder/piston damage you will see it here first as it most always starts at the exhaust port. But, again, with 120 psi of compression I would imagine it will look Brand New...
back to the carb. Get a can of WD-40, the one with the spray tube/straw that you have to place into the spray nozzle, NOT the convenient flip up straw. Not PB Blaster, Not ANY other Lube,... WD-40 with the spray tube/straw taped to the side of the can.
Remove the Carb (again) and remove the diaphragm cover, remove the rubber diaphragm, place the straw of the WD-40 can into the inlet fuel fitting, it should fit snug, while holding the carb up level with the spray tube, give it a short spray of WD-40, release the spray nozzle, wait a few seconds, then trigger the inlet needle up. It should release a short/small amount of pressure... this means your needle is seating good... Go ahead and completely dis-assemble the carb.
Rinse every bit of it with WD-40, blow it through all the ports and the screen.
Look inside the Carb Throat, there are (usually) 3 fuel inlet holes in the side of the bore... two around the butterfly, and one a bit further above the butterfly.
Keep cleaning until you can get WD-40 to flow fairly free through each hole.
(one hole - the one closest to the engine is the low speed/idle fuel, the second one back is for higher speeds, and if it is a big engine there is a third hole, which is more fuel for Wide Open Throttle)
Now, got your Carb all cleaned up? put down a nice clean shop towel, re-clean and rinse EVERYTHING with WD-40 and begin re-assembly. When you get to the inlet needle, pin and lever, go online, look up your Carb and find out how far below Carb Face to set the Lever actuating tab ( if you put in a kit, most of them are right from the package) but it does not hurt to check. finished with assembly?
One more thing, before remounting Carb, (with the CHAIN OFF of the saw) spray about 2 or 3 seconds worth of WD-40 straight into the cylinder, hold the saw down, and give the start cord a good pull. The engine should start before you get the cord half way out. It will run for a few seconds and die out ( smokes a lot when you do this because it is running on oil)
Rinse the carb, boot and gaskets with WD-40 and install them.
Dump all the old gas ( even if you JUST put it in) use a wire and fish the filter from the fuel tank, remove it and either replace it, or blow backwards through it with the WD-40 make sure it flows freely, install filter put into tank and give it a half tank or so of Freshly mixed fuel.
Hopefully, ..... the nice part...
everything in place? Everything tight? re-install the chain.
now.... you have probably turned the fuel mix screw's earlier, so that will need re-done. There are (in most cases) three screws. one is Idle Speed adjust ( this one sets the butterfly position) looking down the throat, back it off until the butterfly stops moving (it wont exactly close) run the screw in until you see it nudge the butterfly and give it about 3/4 turn in
Next screws are lo-speed and hi-speed adjust... Keep in mind when adjusting these if you run a 2-stroke lean, you WILL scald/score the piston and cylinder, always stay just a bit to the rich side.
Close both the lo and hi speed adjustment needles, and re-open them about 2 and a half full turns to three turns. this will start you out rich and might flood but you can adjust them leaner as needed.
Now to tune it
Fresh Gas in? Filter clean and on? check all over and make sure all looks right.
pump the primer bulb about 5 or 6 times, apply full choke and set switch too run.
On the first pull you should hear the engine "pop" a couple of times, set the choke to half on, or full off, if not, pull it again... more than 3 times is excessive. After you hear the engine pop, set the choke to half off, or full off, give it a pull,
Running ? good... blip the throttle a couple of times, is it running right or do you need to adjust the mixture screws? Does it smoke and sputter at idle? run the lo speed screw in about 1/2 turn and try again repeat as needed with both.
I find they usually trim out at about 1 and 3/4 turns to 2 turns.
Get it adjusted? will it sit and idle?
Now for Hi speed adjust wind it up... it should start to flood (Hi speed screw still at 2 and 1/2 to three turns right? let it down to idle, and run the Hi speed screw in half a turn or so and run it up again ... better? worse? adjust accordingly. Keep this in mind when setting hi-speed, there will be a spot where it will run faster than ever before.... this is a bad thing it is too lean, and is burning up the piston and cylinder. A 2 Stroke Always has to run a bit rich for lubrication purpose.
Well, do you have it about where you want it? Smokes a little but not too much? Good Throttle response? Now, put it in some wood. May still need a slight bit of adjustment on the hi speed side, but be careful, remember, Lean BAD.... Rich Good !!!!
....
the worse part...
if all the above did not get it going, check the crankcase for leaks...the piston moving up and down develope positive and negative pressure inside the crankcase... this drives the Carb Diaphragm through the pulse hole.
If the Crankcase has a leak (usually from being dropped or age) the repair here would cost more than a new saw......
When I worked in a Small Engine Shop.... if I had done the above to a saw, I would charge around $100.00 ... and damned if I dont think it took me as long or longer to write then it would to do it...
Prolly something, but from the situation you described, the above should cure it.... with any luck...

 

Back on the #8 post you said the inlet valve wasn't moving freely and you used silicone to free it up. that could be the source of your problem. The silicone spray would come right off once gas hit it.

It definitely sounds like fuel supply to the engine is the problem. The valve hanging up could be the problem, but you really have to find out why it was hanging. It may have been the way the diaphragm was sitting.

I'd see if you can get it started off the primer bulb alone. If not, put a little gas directly into the plug hole and see if it will start off that.If it does, then dies, the problem is likely in the carb pump or a blockage leading to it. That would bring you back to the inlet valve on the diaphragm.

 

Could be timing....Pull flywheel... check timing shim is not sheered ... My craftman 358.350990 which is really a Poulon... had this problem...plenty of spark and fuel...but not even a pop when trying to start...if your chain came off and stopped engine abruptly...this could be your solution..replace flywheel

 

ell i had one of those saws ran it four yrs before she finally died, one time i had the same trouble and the cases are made from plastik so the "magneto" has a tendecy to move just enough to make it not want to fire properly!, make sure the magneto is .025 -.25 dont remeber wich one but anyway if its not exactly that it will not start...good luck