371xp help

[shaunbagone]

This is my father in law's saw. Sat in the shed for 1 or 2 years without use. Couldnt get it started so I dumped out the old gas, cleaned out the fuel line, put in new fuel filter, cleaned plug. Put in fresh gas and saw started right up. Now it will sit and idle put rpm's go up and down, sometimes. I took it out to try and cut and it will scream for about 30 seconds then boggs down. Have to feather the throttle to keep it running. Then it takes off for another minute or so, then does the same thing. I dont really want to mess with the carb settings because I dont really know how to do it correctly. Any ideas?

 

[HiOctane]

Let's say your base setting should be roughly +- 1 turn out on each.Rpm going up and down tells that your LO speed have to be opened a bit,lets say 1/8 out more.Same for HI ,if you need to feather to keep it alive,you are too lean,so open H a bit too.

 

[shaunbagone]

What is the top screw on the carb? I have High and Low screws near the bottom. If I can get it running the top screw doesnt seem to make much difference. I can get it to a point where it seems to be idleing fine but then it will idle up then quit. Have to choke it to get it restarted. None of the adjustments seem to do much of anything.

 

[HiOctane]

What is the top screw on the carb? I have High and Low screws near the bottom. If I can get it running the top screw doesnt seem to make much difference. I can get it to a point where it seems to be idleing fine but then it will idle up then quit. Have to choke it to get it restarted. None of the adjustments seem to do much of anything.

The top screw is your idle speed that increases or lowers your rpm at idle.If she quits at ilde after opening a bit your LO ,then either your carb is dirty or worst,you got an air leak somewhere.Another thing,when you look at carb,opposite side of needles,look for a short tube like a "U" if ist well connected ,not torn or damaged.

 

[Nicholas]

Sounds to me like there's dirt, varnish, particulate matter, water in your carburator circuits/jets. You'll have to completely remove and disassemble the carb, remember to remove the high and low needles too. Blast the carb & parts out with a can of carb cleaner. Then blast it out with compressed air. You may need to repeat this a few times. Also, look at your fuel pump diaphragm. Does it look stretched or blistered out? If so, that will need replacment. Take a look at your inlet needle. Does the viton tip look like it have a ring wore into it? Does body of the inlet needle have light scratches, wear marks, or shiny spots? If so, that will need replacement as well. Now look at the inlet needle pivot rod and lever. If there are wear spots present those will need replacement too. After all the parts are cleaned, worn parts replaced, begin reassembly. Let start with the fuel pump side. Dip the fuel pump diaphragm into some fresh clean mix gas, and align/place on to the fuel pump side of the carb. Now dip the fuel pump gasket in mix gas, align/place on top of the pump diaphragm. Now align/place the cover on to the carb over the gasket & diaphragm. Tighten the screw securely. Now the metering side of the carb. Take the inlet needle and dip the tip in some mix gas, and place the inlet needle in to it's bore. Now the tricky part...Place the pivot rod into the lever, hook the lever into the inlet needle head. With a tweezers or similar instrument, place the spring under the inlet needle lever assembly. Use a finger/thumb to hold the assembly down. Place and tighten the pivot rod screw securely with you other hand. With a straight check to make sure the end of the inlet needle lever is level with the deck of the carb. You will need a small screw driver or two to make adjustments either prying up on the lever if lever is too low, or pressing down on the lever if it is too high. Okay, now dip the gasket in mix gas, and align/place on to the carb deck. Dip the diaphragm in mix gas, shake the excess mix gas off. Now align the diaphragm and place over the gasket. Place the metering cover over the diaphragm & gasket and secure with 4 screws. Now srcew in your high and low needles in to their proper positions. Screw in the needle lightly into their seats and back off 1 to 1 1/4 turns. This is the basic setting to make adjustment off of. If you have access to a pressure/vacuum tester make sure the newly assembled carb hold +0.8 BAR, and -0.4 BAR 30 seconds.

Hope this helps.

Nick G.

 

[Simonizer]

Metering diaphragm has gone stiff. Install a carb kit. Walbro K10-HD. $16.99.

 

[Jacob J.]

You need to rebuild your carb, like Simon said or Simon says.

 

[Nicholas]

Metering diaphragm has gone stiff. Install a carb kit. Walbro K10-HD. $16.99.

Metering diaphragm gone stiff? That's a new one I have yet to see/experience. I have seen metering diaphragms get stretched/loose their elasticity. I have also seen inlet needles adhere to the seat in the carb cause a whole host of power/acceleration problems.

Nick G.

 

[ropensaddle]

Sheesh the poor guy, he posted that he did not know how
to properly adjust a carb, and he now is expected to know
how to kit. Anyway my suggestion is to take it to a local
small engine mechanic, tell him it needs a carb kit and
ask him if he will show ya how it is done! I would not
blow with compressed air.

 

[Simonizer]

Metering diaphragm gone stiff? That's a new one I have yet to see/experience. I have seen metering diaphragms get stretched/loose their elasticity. I have also seen inlet needles adhere to the seat in the carb cause a whole host of power/acceleration problems.

Nick G.

I have seen this a few times, Hmmmm, maybe 3 a week, times 52 weeks/year, times 20 years, yeah 3000 or so, not too common.

 

[HiOctane]

I have seen this a few times, Hmmmm, maybe 3 a week, times 52 weeks/year, times 20 years, yeah 3000 or so, not too common.

Yep,have seen that quite often too.

 

[HiOctane]

Sheesh the poor guy, he posted that he did not know how
to properly adjust a carb, and he now is expected to know
how to kit. Anyway my suggestion is to take it to a local
small engine mechanic, tell him it needs a carb kit and
ask him if he will show ya how it is done! I would not
blow with compressed air.

You are a logical guy,your suggestion is quite valuable.

 

[shaunbagone]

I think I may have had a cracked fuel line. I am trying to replace that right now to start with. What a PITA. I cant get the line into the tank. Any ideas on that?

 

[04ultra]

Cut the end of the line into a point or angle and lude it up and push it through the hole ....




.

 

[bama]

Cut the end of the line into a point or angle and lude it up and push it through the hole ....




.

I use an 8" piece of wire that I poke through the absolute end of the hose to fish it through so I can get a needle nose on it. I always have a hard time getting the hose to stop bending at the wrong time.

 

[Sprig]

This is my father in law's saw. Sat in the shed for 1 or 2 years without use. Couldnt get it started so I dumped out the old gas, cleaned out the fuel line, put in new fuel filter, cleaned plug. Put in fresh gas and saw started right up. Now it will sit and idle put rpm's go up and down, sometimes. I took it out to try and cut and it will scream for about 30 seconds then boggs down. Have to feather the throttle to keep it running. Then it takes off for another minute or so, then does the same thing. I dont really want to mess with the carb settings because I dont really know how to do it correctly. Any ideas?

Haven't gone through the whole thread yet but first off the bolded part of the your statement is the first thing you should have done imho, by not doing so you may have pumped who-knows-what varnishy sludge into your carb, potentially making the diaphram work too hard, plugging tiny holes, etc.. Time for a good cleaning there and/or a rebuild kit. I could be wrong but I've never had fun with any old gas except pourin' it into my pos car with other good gas, small engines are not that forgiving especially newer ones. as usual I stand ta be corrected. Think someone mentioned particles passing through the system too, good thought, but I think a thorough cleaning is in order after that much sitting. As well go over all the lines, pull the filter (the felt ones clean up nicely if theres minimal particles with straight gas soak to get the varninsh out and multiple rinse, at least its worked for me). Good luck and keep us posted eh!
Further ready shows Nicholas is on the ball, but 'blast off' should read 'gently blow' when dealing around the diaphram or non-metal parts imo. Extra care with those needle valves and seats too and super gentle with the jet holes (I use a small soft brass wire, wonder if a horse hair would work? hmmmm....).
Simon probably has the best plan of all! :rockn:



Serge

 

[Nicholas]

I have seen this a few times, Hmmmm, maybe 3 a week, times 52 weeks/year, times 20 years, yeah 3000 or so, not too common.

That's interesting. I'll keep my a sharp look out for that.

Nick G.

 

[Nicholas]

Yeah, take it easy on the compressed air. You don't need to blast it off with 200 psi of air pressure. After washing all the parts in carb cleaner, just blow then the excess cleaner, and loose matter off.

Nick G.

 

[shaunbagone]

Thanks for all the help guys. I changed the fuel line and it runs alot better. I gave it back to him and told him to try it next time he goes out. If he still has problems I will buy a kit for the carb. Doesnt look that hard. I think he wants to sell the saw anyway so who knows.