Fischer Panda Question...

I have the standard Fischer Panda 4200 in my 2006 330 Express. It currently has about 450 hours on it.


I am experiencing a mysterious condition that even the FP Technicians are stumped about. Thought I'd share my story with you and see if you have any suggestions.

After running my generator for about 3 hours, the RPM's (and voltage) suddenly begin to fluctuate up and down.
The generator doesn't stall but I can see on my panel the voltage going from 120V down to about 33V then rising back up to 120V then dropping again. It will do this repeatedly but never stalls.

I have found that when this happens, if I turn off the generator and let it rest for 5 or 10 minutes, it will start up and run smoothly again. It therefore seems like something in there gets HOT and needs to cool a bit - not sure...


In my search for the root cause, have done the following to no avail:
- checked electrical connections to all thermo sensors (3),
- replaced the fuel pump and fuel filter
- replaced the relays to the starter and fuel pump
- replaced the water pump impeller,
- changed and checked the oil level,
- checked the coolant level
- checked the tension on the water pump belt

Any suggestions?

Thanks Ron but no, I have not tested voltage elsewhere in the boat. Not sure what that could conclude or prove.
To your point, I know the A/C shuts down when the voltage drops down to like 33 volts momentarily before it rises back up to 120V momentarily before again dropping down again.

The voltage fluctuates because the generator itself fluctuates (RPM's going up and down like a yo yo). And yes, I need luck on this one as I'm baffled... Might it be a bad fuel solenoid? Could that get hot after 3 hours of use? The FP Technician says the solenoid either works or doesn't so it's probably not that.

Thank you Ron for your thoughts and brain storming. Something in there is getting hot and causing the generator to want to shut down or fuel (or air?) starve. It never actually shuts down though. I'll keep at it and check and test everything.

Thank you Bill for taking the time to supply such detailed information! Excellent info here!

I spoke with another Technician today at FP (named Bob). He was very helpful and was describing things noted in your response above - most of which I do not understand BTW.

Anyway, Bob said for me to disconnect wires 5 and 6 from the thick gray cable that comes from the generator and leads into the AC Control box. These wires are for the Boost Capacitor (per my notes in talking to him). Bob said to be sure to tape off these two wires as they deliver high voltage. He said disconnecting the boost capacitor (wires 5 and 6) will not harm the generator in any way.

So today, I did exactly as he said and my generator ran under a load flawlessly today for 4 hours! Previously it would start to act up in 3 hours or less.

So, I frankly don't understand why the disconnect of the boost capacitors works but it did. So far, this seems to have fixed my ocillating RPM issue.

Does this make sense to you?

Just got off the phone with Bob in the Technical Support Dept. of FP.

Bob said the boost capacitors in my AC Box is a second set and by disconnecting them, he said I should not observe any performance issues. If there are issues, a new AC Box runs about $1,400. He said he would not upgrade the relays because it will not necessarily improve anything (I'm not sure why but that is what he said).

He advised to: 1. Use the generator regularly, and 2. to apply a nice medium load of 15-20 amps by using one major appliance at a time. I have been doing this and he said this is perfect. For example, in most cases, I would only operate ONE of the following: Water Heater, A/C, Microwave, or stove top. This is easy to do while in the cabin at the AC Panel.

So, if I do observe performance issues, I guess I will do the $1,400 solution or send my AC box to FP for evaluation. It is comforting for me to at least know that if I see performance issues, I can zero in on the relays and or a new AC control box. Thanks for all of your help Bill. I appreciate it greatly and feel you got me on the right track here.

Yes agreed on all counts. Thanks and I'll just have to see how it goes running on 2 of 4 capacitors.