Tecumseh Ultima 5hp Engine.

This mower came to me with a fair few problems.

The first was associated with having no spark whatsoever. The coil was dead as a dodo no matter what I tried. After pulling the engine down to check everything out there was no obvious reason why there should be no spark so I replaced the coil from a another Tecumseh that had a rod poking outside the block and hey presto some bright blue spark appeared. I gave it a quick test and the motor fired with a little petrol in the block so that was the first problem solved.

My first question is in relation to the dead coil. I like to understand a little more about why this happens and what can be done to prevent damage moving forward. I am thinking at some point or another the mower may have overheated.

This carby has caused me a fair few problems and I think my rough running problems are associated with fuel supply.

Work done to date:

� Thorough clean with carby cleaner and compressed air.

� O Rings on the emulsifier and jet replaced and reinstalled correctly.

� Sealing gasket found to be in excellent condition and re-installed.

� Top part of carby thoroughly cleaned and re-installed along with the breather hose.

� I cleaned the primer system down and all appears to be functioning correctly as I can get nice easy one pull starts.

Now here are some further problems � no matter how I adjust the speed screws near the carb, I cant make it stop chugging or change the speeds. The mower doesn�t stall it keeps running but its chugging and smoking just a little like its running rough. The plug when inspected was a little blacker than I thought it should be. If I put a good splash of fuel down the hole the engine sings sweetly for a few second and then it goes back to chugging away toughly

I am think there is something I might have missed so I would appreciate some suggestions.

Note: Compression registered at just over 100psi so I think that shouldn�t be the problem.
I have included a couple of photo�s below which show the mower is in quite good condition.

I have done a fair few of these utima�s know so I know the carb�s reasonably well however in this case I must have missed something!





[Linked Image]
[Linked Image]