BX tach needle sticks.

[frogpond]

I have a BX25D with about 650 hrs. When I start it up, the tachometer needle goes way up, as usual, then down to zero, then stays there instead of going up to slightly above idle (where I set the throttle to start). At the same time, the battery light stays on. Both of these persist until I goose the throttle higher, and then the needle comes up and the light goes off.
I have checked under the hood while the needle is zeroed and the light is on, and the fan and alternator are turning. When I check the belt (with engine off, of course), the deflection is normal.
Any theories? No problem running, but I am worried that this might be advance warning of things to come.

 

[dodge man]

How’s the battery? Just a guess but is it a little weak?

 

[BleedingOrange]

Check the tightness and wear on your alternator belt, just in case it might be slipping.

 

[oldballs]

Maybe the tach cable is about to break...just a guess.

 

[frogpond]

Thanks for the suggestions. I'll be able to check on Sunday, and report back...except, how do you check the tach cable?

 

[dodge man]

Does it have a cable? I’ve got a 10 year old BX and the tach is digital. It might not have a cable and be electronic.

 

[Agvg]

Your tach does get the signal from your generator, so missing tach and charge lamp are symptoms of the same problem.

 

[frogpond]

Well, the belt does deflect about 1/2", which is slightly more than spec. To adjust it, you oosen the alternator mounting bolts...but it appears that to get a wrench on the lower one, you have to take off the whole engine shroud. I think I'll wait until it gets worse.