Bobcat turns over but rarely starts then runs excellent

[Johnskid]

My old bobcat with a 1.6 engine (732) turns over but rarely starts. Once it does it runs excellent though. I have added a new electronic ignition, plug wires, plugs, new coil, and it runs better with these but still does not start better. Anyone with a similar problem that they solved?

 

[farmshop]

Is there spark? Have you tried so either to see if it fires? Need to determine if you have a spark or a fuel problem

 

[walio123]

Is there spark? Have you tried so either to see if it fires? Need to determine if you have a spark or a fuel problem

There may be many reasons. Incorrect ignition timing /more advanced/, incorrect distance between the spark plug electrodes, Most probably a poor fuel-air mixture.By the color of the bottom of the spark plugs you can understand a lot. When working properly, they are red- brown in color and dry. When the ingition is too advanced they are white, in a poor air-fuel mixture they are also white. With rich air-fuel mixture and ignition timing delay they are black- blue and wet. After you've changed everything in the ignition system ... the carburetor remains to deal with. Sorry for bad English language.

 

[craigb93]

There may be many reasons. Incorrect ignition timing /more advanced/, incorrect distance between the spark plug electrodes, Most probably a poor fuel-air mixture.By the color of the bottom of the spark plugs you can understand a lot. When working properly, they are red- brown in color and dry. When the ingition is too advanced they are white, in a poor air-fuel mixture they are also white. With rich air-fuel mixture and ignition timing delay they are black- blue and wet. After you've changed everything in the ignition system ... the carburetor remains to deal with. Sorry for bad English language.

Start with the suggestion above and verify that the ignition timing is correct-10degrees BTDC and that the vacuum advance diaphragm is not leaking and therefore functional. After that the carburetor main jet and the immulsion tube must be cleaned. Both of these can be cleaned with the correct size number drill. DO NOT enlarge either one, just be sure they are clean and restored to their original size. Ethanol fuel will leave a scale deposit that reduces the orifice size and thus a too lean mixture. Carburetor cleaner does not remove deposits like this. Whether your carburetor is a Zenith updraft like mine or a different brand, the cleaning method is the same. -Dick [The tube has 6-holes across plus the main tube itself. Don't overlook cleaning the anti-dieseling solenoid on the carburetor bowl inlet if so equipped.]

 

[Johnskid]

Start with the suggestion above and verify that the ignition timing is correct-10degrees BTDC and that the vacuum advance diaphragm is not leaking and therefore functional. After that the carburetor main jet and the immulsion tube must be cleaned. Both of these can be cleaned with the correct size number drill. DO NOT enlarge either one, just be sure they are clean and restored to their original size. Ethanol fuel will leave a scale deposit that reduces the orifice size and thus a too lean mixture. Carburetor cleaner does not remove deposits like this. Whether your carburetor is a Zenith updraft like mine or a different brand, the cleaning method is the same. -Dick [The tube has 6-holes across plus the main tube itself. Don't overlook cleaning the anti-dieseling solenoid on the carburetor bowl inlet if so equipped.]

Thanks for all of the good advice. I will give these a try!

 

[Wayne440]

Thanks for all of the good advice. I will give these a try!

The first thing I would check is to verify that the choke plate closes properly when you pull the knob. My 742 has a similar engine and does not start well cold with less than full choke.