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Discussion Starter #1
Last summer it had spark but wasn't getting fuel.  Now I just rebuilt the carb and I noticed i'm getting no spark on either side.  75 tnt 340 fan.  I don't know anything about points and condensors, i think this is where the problem is.  I did make sure the kill switch was working.  I do have a multimeter for diagnostics but not sure what to check or what to do??  HELP!!!
 

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remove the recoil [starter recoil]behind that there is a pulley take the three bolts out of that remove the crank bolt with a 3 jaw gear puller pull off the pulley uwill see the magneto there are little windows in it thepoints can be filed through the window this sounds much harder than it realy is i did it on my old 399 it takes about 30to45 minutes this should take care of your problem if not you my need to replace the points hope this helps
 

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Discussion Starter #3
Yup, you were right corvette 77, I cleaned the contacts now I have nice blue spark.  Next problem:

I am right where I left off from last year.  I just rebuilt the tillotson HD carb.  But it won't suck gas!  When I put gas into the cylinders, it pops off first pull then dies right away.  HELP! I'm sooooo close. :0
 

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Make sure your impulse line and fuel filter are not blocked or loose-also check your carb diaphrams to make sure you don't have any little tears.
Hope that helps
 

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glad my info helped as for the carb remove the carb remove the fuel pump you will see a spring loaded lever that controls the needle and seat unscrew the screw just enought to remove the lever be carefull not to lose the little spring remove the needle take a small drill bit and holding it by hand spin it in the seat area using light pressure this will take the sharp edge off the seat reassemble the carb if this works you may run it like that or get a new needle and seat i have done this many times and most of the time it works but not always  but it is definitly the needle and seat that is causing you problems hope this helps
 

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hey mopar i have a 75 tnt440fan and just got a tnt340 fa for 30$ also have 70 399 nordic and 72 640 nordic i realy enjoy makein these old sled stay runnin im not a sled tech but i havent hade any problem figureing these sleds out did you figure out your carb problem yet?
 

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Discussion Starter #7
you have quite the collection  


Well I got part of my question answered.  Your advice once again helped.  You were right the needle was not dropping, it was stuck.  So I cleaned that out.  I had to install a primer to get the fuel to the carb, I hope this is ok?  I then got the sled to idle but it will only idle on choke, as soon as I take the choke off it dies right away.  I did notice that the impulse nipple on the crankcase (which I don't need with my carb) was NOT plugged.  I am going to try plugging that up.  Do you have any other suggestions?  The carb is a tillotson HD, both needles are set at 1 turn out.

Thanks for all your help.
 

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you said you rebuilt the carb did you also rebuild the fuel pump it should not need to have a primer to get the fuel to the carb you can also check to see if the port that the fuel pump gets its vacume from is open if you take the carb off at the bottom of the manifold you will see a small hole this is where the fuel pump gets vacume from make sure it is open and also check to see if the hole in the carb is clear if these ports get clogged the fuel pump will not work if they are clear you might have to get a fuel pump rebuild kit go to                   MFG supply.com they have them pretty cheap another thing you can try you said the motor has a vacume port try putting an external fuel pump on it and run the gas line thats on the bottom of the carb to the the inlet side of the external pump and the outlet hose to the filter on the bottom of the carb
 

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another thing i forgot to mention is make sure the pickup tube in side the tank is good when they get old they get hard and normal rideing will make them crack i fought with my 640 for hours trying to get it topick up fuel then i notice bubbles in the fuel line so checked the pickup tube and found that there was a crack at the top it would suck air and gas but not enough to fill the filter if the filter is not full the carb cant work
 

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Discussion Starter #10
I did replace all intake hoses with new ones.  I did also replace all the "guts" or fuel pump gaskets and diaphrams.  I will take the carb off and look for this hole you speak of.  It must be getting some vaccum because the motor will idle on its own with the choke on, it just dies once I take the choke off.  I just use the primer to get it going for the first time.  Thanks for all the help!
 

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Discussion Starter #11
Ok, getting a little closer.  I found out that when I cleaned the needle and seat I forgot that little brass washer.  I put that back in and I could turn the choke from all the way on to about 3/4 of the way on and the motor wouldn't die and I could rev up the motor.  BUT, there was a bog at first when I pushed on the throttle.  And when I took the choke all the way off it would die.
  Damn I can't seem to figure this out.  Should I be able to run this motor with choke all the way off?  Am I at a point where I should just mess around with the low speed needle?  Is it possible the crank seals are leaking?  HELP???
 

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It could be your crank seals. Fire it up and try to keep it at a steady idle, choking or not. Spray starting fluid on the pto side crank seal behind the clutch. If it revs up at all, then you need to replace. We did that on our Raider this fall and it runs good now and it's cheap to fix too.
 

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It could be just a matter of turning out the low speed needle a bit although I doubt it. I was wondering if you took the welch plugs out of the carb when you rebuilt it and cleaned out the passageways under them. Also the inlet control lever adjustment is very critical on these carbs. I will send an information sheet for a Tillotson carb to you in case you did not get it with the rebuild kit. I guess it will have to come as a private message as it is too large to post here. Here is the inlet control lever setting though.
 

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Discussion Starter #14
Didn't do welch plugs because I only bought the kit that does gaskets and diaphrams.  So I don't have any new welch plugs to put in.  Maybe I'll try soaking it, and check the lever.
 

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Discussion Starter #16
Thanks for the info Paul,

Ok, got a never used tillotson carb via e-bay today.  Put it on and the sled did the same thing.  It only ran in choke, the second I took choke off it died.  It appears I'm getting good spark but maybe not.....

When I do go from choke to no choke I quick give her the throttle and it revs up, track spins and everything, but the second I let off the throttle it dies, not sure if this helps.  I'm getting frustrated!  
 

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Well it sounds like you have more serious problems than first indicated. You may have an air leak which is leaning out the mixture so that is why you need the choke on. The air leak could be the outer crank seals or leakage where the crankcase halves bolt together. I believe you said you changed the carb mounting adapter so that should be good. The inner seal in the crankcase could be shot so there is not enough suction to pull in enough gas for it to run normally. Thirdly maybe the compression is way low. Try backing out the low speed needle a few turns until it will run on its own and then spray the WD40 or starting fluid around to check for external air leaks.
 

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Hey Mopar4u how much did you pay for you tillotson carb from ebay?
I am having some similar problems with my 69 Olympic.  But mine wouldn't even start untill after I rebuilt the bottom end of the 335cc engine.  Put new bearings and seals.
Now it will idle fine but when you give it gas it just bogs and almost stalls.  I have rebuilt my carb also.
Let me know how yours goes and maybe I might have the same problem.
Matt
 

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Discussion Starter #20
I paid $22 with shipping.  Turns out I didn't need it.  Make sure you have your 2 outter needles set properly and the internal needle.  Probably wouldn't hurt to replace all fuel line.  Oh yeah, don't make the same mistake I did, make sure you have the impulse line hooked up (although some used the small hole on the flange part of the carb instead of the hose which may need to be cleaned out).
 
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