Having issues with my Onan microlite 4k generator. I think the voltage regulator (model 305-0851) may be at fault. Before replacing a $200-300 dollor part can someone give me a testing procedure or literature on how to test?ThanksGenorater starts but stalls as soon as the start button is released. It is producing power just won't run off its own power. Possibly a relay in the regulater. But it is a sealed non serviceable part. pcb is in a box and covered with epoxy??

I don't believe there is a way to test it. When mine went bad it was all one unit and cost was $1800 for the part for my diesel generator.

What is the spec letter on that 4k and I'll post a service manual. There are a lot of of things that it could be need to test them before you buy that brain and it still does the same thing. Don't just just start throwing parts at it ..Start by looking at all connections then the start soleniod. When you let off the start switch it has to be making power to run. How many hrs are on the unit ?

There is an excellent guide (link to pdf file) on the Flight Systems website. They also sell the best, imho, replacements.

Model # 4KYFA26100BAbout 2500 hoursOil sensor has been unplugged and grounded. Remote panel disconnected. Same result. when running (with start buton pressed)it's does produce power.On very rare occasions it will run normally, when it does it's rock solid which leads me to believe its a mechanical failure like a stuck relay.

Here you go. 981-0503 ky service manual

Onan V/regulator testing | Good Sam Community

Ranger_Smith
Explorer
Jun 09, 2014
I don't believe there is a way to test it. When mine went bad it was all one unit and cost was $1800 for the part for my diesel generator.
Kpackpackkelley
Explorer II
Jun 09, 2014
What is the spec letter on that 4k and I'll post a service manual.
There are a lot of of things that it could be need to test them before you buy that brain and it still does the same thing. Don't just just start throwing parts at it ..
Start by looking at all connections then the start soleniod.
When you let off the start switch it has to be making power to run.
How many hrs are on the unit ?
Chris_Bryant
Explorer II
Jun 09, 2014
There is an excellent guide (link to pdf file) on the Flight Systems website. They also sell the best, imho, replacements.
Cstoliker
Explorer
Jun 09, 2014
Model # 4KYFA26100B
About 2500 hours

Oil sensor has been unplugged and grounded. Remote panel disconnected. Same result. when running (with start buton pressed)it's does produce power.

On very rare occasions it will run normally, when it does it's rock solid which leads me to believe its a mechanical failure like a stuck relay.
Kpackpackkelley
Explorer II
Jun 10, 2014
Here you go. 981-0503 ky service manual
Kpackpackkelley
Explorer II
Jun 10, 2014
Chris Bryant wrote:
There is an excellent guide (link to pdf file) on the Flight Systems website. They also sell the best, imho, replacements.

I believe flight systems will test old one for 25.00
Generator_Jim
Explorer
Jun 10, 2014
***Oil sensor has been unplugged and grounded ***
Remove the ground, that's how the oil sensor shuts the unit down.

JimL
Ranger_Smith
Explorer
Jun 10, 2014
Generator Jim wrote:
***Oil sensor has been unplugged and grounded ***
Remove the ground, that's how the oil sensor shuts the unit down.

JimL

Is it a normally closed sensor that opens with pressure or is it a normally open sensor that closes with oil pressure. I thought it was the latter.
Handbasket
Explorer
Jun 10, 2014
Ranger Smith wrote:
Generator Jim wrote:
***Oil sensor has been unplugged and grounded ***
Remove the ground, that's how the oil sensor shuts the unit down.

JimL

Is it a normally closed sensor that opens with pressure or is it a normally open sensor that closes with oil pressure. I thought it was the latter.

Micro-series are splash-lubed. No oil pump, so no oil pressure to operate a switch. If it's got a low-oil safety, it's probably a float.

Jim, "Life is short. Drink faster."
Kpackpackkelley
Explorer II
Jun 10, 2014
Some spec's had a low oil switch.