Generator Problems

[Joebus]

I have had problems with my genset (7.5 Onan DKD). sent it to a repair shop (Onan authorized) $ 1005.00 later and still not right.
Problem; no load= 119.8 VAC, as load is applied VAC decreases, 20 amps= 101 VAC, and down from there. I am sure they will take it in the shop again, but they are slow, (a month so far) and will continue to charge to replace parts until it is done.

I need to speed this up and maybe have some money left in the bank. This unit has a transformer regulator, I think it may be the problem, but the shop doesn't agree....yet. Any suggestions or prior experience

Do not want to leave for warmer area's without it. 

[wrench]

   Run it with a small load (20 amp),  does it smoke(black)?  check air filter, fuel filter,  rubber hose from the tank for crack,  It may bog down under load because starving for fuel or air.  With the same load, you can cut one injector at time by cracking the injector nut loose, that will tell you if the injector & each cylinder are working.  If one is bad there will not be much difference as the engine run when you open that injector.
     Are you in the south?
            wrench

[Dreamscape]

I sent you a PM that might help.

Paul

[desi arnaz]

ask sean   he will know

[Joebus]

Thanks
wrench: motor never changes (1805 rpm) regardless of load...just VAC. We are still in Ontario getting cold
Paul: thanks for the PM, I have now posted as well.

[robertglines1]

guess you have checked the easy things..I had a 15 kw Onan that dropped voltage under load..cussed and pulled hair out--turned out to be worn out breaker on gen set..when the load came on  the breaker would heat up and not tripp but would loose partial contact--would have been better if it just tripped..no scientific reason..changed it and all was well..sometimes we can't explain the why--I don't have the education just the result. look for something that doesn't seem rite  discolored  loose connection  smell   corrosion..does voltage drop on both legs?

[Sean]

If the RPMs are rock-steady (does not bog down under load, etc.) that tends to rule out governor problems as well as anything mechanically wrong with the engine.

If this is a transformer-regulated set, as you mentioned earlier, then there is a good possibility that all that is required is to "flash the field."  Your generator manufacturer should be able to provide instructions for this procedure on your set.

Alternatively, if this is an electronically regulated set, it sounds like a bad regulator.

If the set is transformer-regulated and the field is properly flashed, there is a simple terminal-strip adjustment, usually, to set the voltage.

If you post the complete model number from the nameplate I might be able to look some of this up.

-Sean
http://OurOdyssey.BlogSpot.com

[Sean]

... dropped voltage under load... turned out to be worn out breaker on gen set..

This is an excellent point -- I presume you are measuring the voltage AT THE HEAD, not at the load.  If not, you definitely want to measure at the head.  If there is a substantial difference between the voltage at the head and the voltage at the load, you could have a problem with the wiring such as too small a gauge, or loose connections at a terminal somewhere, or even a bad main breaker as Bob describes.

-Sean
http://OurOdyssey.BlogSpot.com

[Joebus]

Thanks to everyone for your responses. I took it back to the repair shop, they called a couple hrs later. Told me they could find anything wrong with it, and it muast be a bus problem. I returned and checked it at their shop and was ok so  I brought it home installed it as normal. Works great. So I am happy .
Thanks Joebus

[FloridaCliff]

Thanks to everyone for your responses. I took it back to the repair shop, they called a couple hrs later. Told me they could find anything wrong with it, and it must be a bus problem. I returned and checked it at their shop and was OK so  I brought it home installed it as normal. Works great. So I am happy .
Thanks Joebus

Joe,

That's generator repair speak for " we found what we didn't do or hook back up"

Glad your your back in the power generating business

Cliff

[gus]

Cliff is probably right, if he isn't it will happen again just when you most need it!!