Need help, believe I have a fuel problem

[BigRed96]

I rebuilt a MS200t for my Father to give him as a Christmas present. Currently I can get the saw to pop with the choke on, then I can get it to start and run on high idle for a second or two. A little history on the saw. I bought the saw doing pretty much the same thing and tore it down. I did not split the cases. I replaced the seals, put in new piston rings, cleaned the carburetor in my ultrasonic cleaner and rebuilt using a kit. The impulse and fuel line are brand new, however I can't remember if the filter is or not. One problem the I do have is the damn flippy cap on the fuel tank leaks. I have pressure tested the fuel line and visually checked it for leaks and it seem good. Also the fuel tank vent is brand new and seems to be function. I put oil in the impulse line and it blows back out when you pull the starter so I think its clear. I am pretty good with the carburetor rebuild having done a bunch of them. At this point I don't know what else to check. Btw also vacuum tested and pressure tested the saw and it passed both test. I also inspected the intake line for cracks and didn't see any. I set the flywheel gap using the business card method. Anyone have any suggestions?

 

[Czed]

Check your low setting on your carb I've had similar issues. Just a thought.

 

[BigRed96]

Check your low setting on your carb I've had similar issues. Just a thought.

It is one turn out.

 

[Mark71gtx]

If memory serves, that 200T carb has so.e funky check valve or something like that, that can be a bugger at times. @Lone Wolf would probably know better than anyone about a 200T.

 

[Czed]

I rebuilt one and had to eventually replace it just wouldn't hold it's settings.

 

[Chainsaw Jim]

Fuel filter or bad carb... possibly both.

 

[BigRed96]

Fuel filter is easy. I will replace it. I tried another carb the was a walbro for a 200t and had the same problem. Previous owner said the carb was brand new. I disassembled it and it looked good. Still same problem though. That is why I rebuilt tho Zama.

 

[Chainsaw Jim]

Don't be afraid to disassemble it all the way down to the bare crank if the filter doesn't fix the problem. No specialty tools or heat needed, the case easily pulls apart by hand and the bearings are a different style allowing them to slide right off the crank. The seals stay in place without being damaged.

 

[Mark71gtx]

If you are having the same problems with multiple carbs. I would look elsewhere. Filters are cheap and easy. Put a new plug in it. They are cheap too.

 

[Lone Wolf]

I rebuilt a MS200t for my Father to give him as a Christmas present. Currently I can get the saw to pop with the choke on, then I can get it to start and run on high idle for a second or two. A little history on the saw. I bought the saw doing pretty much the same thing and tore it down. I did not split the cases. I replaced the seals, put in new piston rings, cleaned the carburetor in my ultrasonic cleaner and rebuilt using a kit. The impulse and fuel line are brand new, however I can't remember if the filter is or not. One problem the I do have is the damn flippy cap on the fuel tank leaks. I have pressure tested the fuel line and visually checked it for leaks and it seem good. Also the fuel tank vent is brand new and seems to be function. I put oil in the impulse line and it blows back out when you pull the starter so I think its clear. I am pretty good with the carburetor rebuild having done a bunch of them. At this point I don't know what else to check. Btw also vacuum tested and pressure tested the saw and it passed both test. I also inspected the intake line for cracks and didn't see any. I set the flywheel gap using the business card method. Anyone have any suggestions?

I wonder if the impulse line is blocked from the oil?
. Did you try a carb that was a known runner? I know the guy said it did but did you take it off a running saw? If you want it running for Christmas get moving ,times running out. Blow the impulse out with carb cleaner that oil you put in there could be the problem . If the saw was vac and pressure tested like you said its prob the carb after you try clearing the impulse line, then buy a carb . You can get an aftermarket carb from Definitive Dave or you could send me the saw.

 

[BigRed96]

I wonder if the impulse line is blocked from the oil?
Try an aftermarket carb from Definitive Dave if that dont work send it to me . Did you try a carb that was a known runner? I know the guy said it did but did you take it of a running saw? If you want it running for Christmas get moving ,times running out. Blow the impulse out with carb cleaner that could be the problem . If the saw was vac and pressure tested like you said its prob the carb.

I don't think fuel is even getting to the carb. I will go to the dealer tomorrow and try the fuel filter. Simple enough. I have 6 or 7 carbs for these saws. That would be great if it was just a filter. I only put oil in the impulse after I couldn't get it to run. I will spray it out with cc tomorrow and give it another try.

 

[Lone Wolf]

I don't think fuel is even getting to the carb. I will go to the dealer tomorrow and try the fuel filter. Simple enough. I have 6 or 7 carbs for these saws. That would be great if it was just a filter. I only put oil in the impulse after I couldn't get it to run. I will spray it out with cc tomorrow and give it another try.

Prob aint the filter. Is there even a filter on the fuel line, maybe missing? Take the line off the carb and see if fuel comes out when you tip it. Blow the impulse out with carb cleaner too. Did you use a new impulse line?

 

[Lone Wolf]

Did you forget to connect the impulse line under the handle?

 

[Stump Shot]

Check your spark plug, if it's wet you may have a weakened coil. I just went through this with a saw, had spark but it was skinny and weak. Would pop, fire for a little then nothing. Not only should it be able to jump about a 5mm gap, it also should be a nice thick blue color. If it's pink, white or faint blue your coil is suspect.
If the spark plug is bone dry, go back and look through the fuel system again. Sometimes they have a hard time pumping air at pull start speed, spray a little fuel in the carb throat or the spark plug hole usually after a couple tries with this, it should be primed up and running.
Check the muffler/screen for obstruction.
Also compression should be over 100PSI.

 

[BigRed96]

Prob aint the filter. Is there even a filter on the fuel line, maybe missing? Take the line off the carb and see if fuel comes out when you tip it. Blow the impulse out with carb cleaner too. Did you use a new impulse line?

Yes there is a filter on the line. Will do on the tipping the saw. Impulse is brand new.

Did you forget to connect the impulse line under the handle?

Nope, it's connected. One thing I did check already.

Check your spark plug, if it's wet you may have a weakened coil. I just went through this with a saw, had spark but it was skinny and weak. Would pop, fire for a little then nothing. Not only should it be able to jump about a 5mm gap, it also should be a nice thick blue color. If it's pink, white or faint blue your coil is suspect.
If the spark plug is bone dry, go back and look through the fuel system again. Sometimes they have a hard time pumping air at pull start speed, spray a little fuel in the carb throat or the spark plug hole usually after a couple tries with this, it should be primed up and running.
Check the muffler/screen for obstruction.
Also compression should be over 100PSI.

One thing I didn't check was muffler. The spark arrestor has already been removed. I did put my hand over the exhaust port while pulling the starter. It's moving air through. Will check compression tomorrow. Should be good being brand new Stihl rings.

 

[Chainsaw Jim]

I've noticed more than one of these with bad fuel filters. They still look good but get really restricted.
You can easily test by poking a hole in it or pulling it apart to remove all the guts so the fuel line gets direct flow. It'll ruin it if it is a good one, but it'll still work for further troubleshooting until you replace it.

 

[Lone Wolf]

I am curious as to how much compression it has. It can have an air leak even if you tested it believe it or not. I might bet on the carb after you check the fuel flow and blow out the impulse line.

 

[Lone Wolf]

I've noticed more than one of these with bad fuel filters. They still look good but get really restricted.
You can easily test by poking a hole in it or pulling it apart to remove all the guts so the fuel line gets direct flow. It'll ruin it if it is a good one, but it'll still work for further troubleshooting until you replace it.

Just take the line off the carb and see what it flows like.

 

[Chainsaw Jim]

Just take the line off the carb and see what it flows like.

The thought is good until you realize you don't have anything that will weigh the line down to keep it submerged.

 

[Lone Wolf]

The thought is good until you realize you don't have anything that will weigh the line down to keep it submerged.

Fill the tank first