mf 135 not firing

[Mike476]

http://l-36.com/carb.pdf

If the rebuild kit was for the Marvin Schebler, was the idle needle tip rubberized. Mine was, and caused a lot of the same symptoms yours is. After installing the original and vacuum checking with a propane torch it was running quite a bit better, but still needed adjustmenst as stated earlier.

 

[tcsarge]

i finally figured it out it took awhile but its running great, i took some fine sandpaper and cleaned the points and it started right up thanks for all the advice. Tim

 

[Soundguy]

YIKES!

if nothing else get an ignition hone.

I've found brown grocery sack or even white typing paper is the best cleaner for points.

sand paper leaves grit that will cause arcing and pitting, not to mention it pretty heavilly removes the hard coating off the contacts.

soundguy

 

[Mike476]

Guess I assumed you had purchased the kit when you stated you had changed ignition parts, I've found I have to change points on mine every year, button / condensor and cap about every second or third year.

 

[Soundguy]

every year? OUCH! something ai'nt right. My 'youngest' set of points on an tracor I have with battery ignition is either 5ys old or older, unless i put a new set in when I bought it, if I'v owend it less than 5ys.

my oldes set is going on 11ys now.. I have a few tractors that are still on their set of points i bought hem with.. and at least one of those appears to be an oem vintage set. not probably the ORIGINAL set.. but at least a vintage one...

soundguy

 

[Mike476]

It does seem odd doesn't it. It's not that they burn out, or that I couldn't probably get a few years out of a set, but with where I live I've found they begin to pit (atlantic coast) just enough that it takes a few more revolutions to start and idles just that little bit rougher. Could clean / re-gap them but for 7 dollars and 10 minutes work I just replace them. I like to walk up, turn the key and within 2-3 revs start it up, whether in the coldest winters day with the choke pulled or mid-summer, and I've found the difference of whether I can do that or not are the points.

 

[Soundguy]

pitting is usually a sign or excessive primary current, and / or they are not setting square, thus the entire surface area is not conduction the current, making hot spots and or arcing.

For kicks, try a premium quality set of points.. not a economy set.

most economy sets are les sthan 10$.. most premium are 18-25$

that and make sure your coil or coil and resistor is correct for your system voltage, and see what you get.

soundguy

 

[Mike476]

Not setting square was what I had first thought might be the problem, but they were fine. Radial play on the distributor shaft is also good, there is some but within tolerances and I've cross-referred the part numbers of the coil and ignition components thinking sometime during it's life someone might have changed the distributor, but it's OEM.

You're right that a better quality set of points will provide longer life, haven't been told that ones exist for the old girl but will do a little research.

 

[WilliamBos]

Does an electronic ignition kit exist for these?? I would ditch the points in a heartbeat ...

 

[Mike476]

Don't know about electronic ignition but points are easy enough to replace and inexpensive, even if I do find a higher quality set at or around the 20 dollar mark. Now if the distributor was in an inaccessible location I'd be looking for a more permanent solution, but to me the 10 or 15 minutes it takes just gives me another reason to spend a little quality time with the old girl, and thankfully that's not how these basic old tractors were built.