KAD32 Engine fuse popping - trim control issues?

[Somerset Taz]

Hi All,
I have a number of strange electrical issues that might all be related. First, the port engine tacho works fine until the starboard engine is started, then the port tacho seems to drop and then get stuck at around 1100 revs. When the port engine is running on its own (tacho reading correctly) and I beep the trim switches (switches are on the port throttle leaver) the tacho drops about 500 revs on the scale then recovers when the trim switch is released. When both engines are running the starboard tacho is unaffected by the trim adjustments. Also recently, the port engine has started popping the main engine fuse. This does not seem to happen when the supercharger is engaging or disengaging. In all other respects the port and starboard engines perform very well - they start first turnover, are able to reach the spec WOT, no cooling issues, alternators 14v etc (engines approx 250 hours and regularly professionally serviced). Could the throttle and/or trim switch be causing these issues? Any thoughts out there from the gurus gratefully received.

 

[Aardee]

Probably no help here, but if this were a car with seemingly unrelated electrical issues I'd be checking all the earthing points...

 

[BruceK]

Not a guru just some thoughts


On my control levers there is a neutral microswitch. If it is faulty it can cause the breaker to pop. (Been there done that many times)

I have had gauges act in a similar way to yours when both panel sets take from a common starter battery and one loom has more resistance to it coupled to twin fuel tanks with separate fuel gauges that share a common positive. (Weird I know but verifying the fuel gauge connections are good solved it - some VDO fuel gauges have voltage rectifiers in them) . Also the two seperate systems can often be cojoined by sharing a common instrument light switch However I do not suspect this being your issue but probably more to do with a bad loom connection creating resistance. Pull them all apart and clean using a good switch cleaner. As for the micro switch I just forwent the damn thing and completed the circuit. Two yellow wires per lever.

 

[Somerset Taz]

Thanks for the advice. Will check out the throttle trim switch and instrument panel wiring next.