Idles but doesn't rev up.

[rivergold]

Hi JDers,

I am new to this site, glad I found it. I have a 78 spitfire 340 kohler that will start no problem, but will only idle and not rev up. I have ruled out carb, fuel pump. I believe it is a CDI ignition problem. I cleaned up the coils.....didn't make a difference. I replaced the CDI unit with another used one. It ran perfect again for about 2-3 minutes then went back to doing the same thing, wouldn't go more than idle. I would rather not put another CDI in for fear of it blowing again. My questions are (#1) what is blowing the CDI unit? Or (#2) is it even the CDI unit? I tested the old one with ohmmeter according to the service manual and it didn't check out as indicated. I didn't test the 2nd used one I put on until after I installed it, but it too now is no good according to the manual. (#3) Is the JD service manual correct for ohm testing the CDI? Someone said it could be running off one coil, not providing enough spark for anything past idle speed. I will try an ohmmeter test on coils too. Any suggestions? Anyone have this same problem?

Thank you all!

[Matt]

You need to test your stator (internal coils) with the ohm meter, and I am not sure on this, but that may be what the service manual is referring to. There is no way to test a CDI box with a regular meter. Stators and external coils, yes.

[rivergold]

Opps! next time I will post in the right category.....

And Matt, my tech manual does have a ohm test procedure for the CDI unit. I agree, I need to test the coils next. Thanks for reply.

[SpitfireKing]

Silly question, but the track spins by hand nice and free? And if off the ground and just a tiny bit of throttle it will move? I have a 80 spitfire that did the same thing, just seemed to be a ground issue.

[jd4455]

How old is your gas ? I had 3 friends this year that got there sleds out this year and worked on them for hours, they asked for help they said they would idle and that was about it. they had a hard time to just dump all the old gas out and start with fresh gas that would burn. They were surprised to find out how great there sleds ran after that.

[rivergold]

My track does not run freely Spitfireking. I'll check into that also. And jd4455, my gas is new, I had been using the machine up until this problem and it ran perfectly.

Are new CDIs available anywhere? I really just need to !

[SpitfireKing]

I've more often then not found that cdi's either work or they don't... I think you need to search out the other issues before that investment. If your track won't spin then that's a first issue, maybe it's adjusted way too tight or bad bearings, or possibly a secondary issue?