Dolmar MS 253 Weedeater won't start

[sgruver78]

I bought this machine about 6 years ago but it hasn't been used for about 4 years since I moved and didn't need to use it anymore. Well now I bought a new house and I can't seem to get it to fire but to be honest with you even when it was new it was kinda hard to start when cold. Anyway, I am not a total novice when it comes to small engines, I can normally figure these things out relatively easily but this one I am stumped. This is what I have so far: it has great spark and the compression seems more than adequate to run. I just did a carb rebuild so I know its not the diaphragms in the carb. I removed the air cover and sprayed gas directly into the engine and you would think I would get a little bit of fire but I yank and yank forever and I could not get it to kick over one sputter. What could be the problem? Could it be that I have great spark out of the engine but when it is in the cylinder it is not producing enough? I can't think of anything other than that...let me know if anyone has any other ideas.


Thanks!

 

[577jersey]

What do u mean by great spark,Is the spark a nice bright blue color or orange?
Also,did u replace the spark plug,,sometimes when they get a little wet with fuel they foul easy when old?
I would put a new plug in,and go over the carb again making sure you have all the little jets cleaned out using a steel guitar string and cleaner with compressed air...make sure the high and low jet is set at 1 to 1-1\2 turns CCW each,,that should get you going.
Then see if the plug gets wet when you try to start it..I know you said you put fuel into the chamber and nothing but try again.
Also make sure the spark is constant,maybe you have an intermittent problem with a broken wire or dirty switch causing it to loose spark especially when you jolt the machine while pulling it over.

All u need is spark,compression,air and fuel too at least fart that engine.

Tom

 

[sgruver78]

definitely bright blue spark, i will try the new plug and hopefully that will do it. thanks for the help!

 

[577jersey]

Well that’s a great sign,,if you have good compression,it should fire by just dropping an oz of fuel in through the spark plug hole...if not I would suggest investing in a cheap compression tester from HF...i assume its a 2 cycle and you should see 100+ PSI after a few pulls.

Tom