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My 8KW 1.0L Diesel generator will start up OK. Then the starter kicks in again after it is running. I was told that it was either low oil pressure or a defective oil Pressure switch. I added a oil pressure gauge 45PSI and replace the oil pressure switch with a normally closed switch that opens at 8 PSI. I even tried disconnecting wire 85 to the control board after it started, to rule out that one of the other safeties wasn't triggering this. It appears something else is telling the start sequence that the generator isn't running..... Need ideas where to look.



Generac 8KW Engine # 70939 1.0 L Shibaura S753 Alternator Data: Model 00449-0 SN 3113852 120/240v 1800 RPM



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sorry late to the party..
do you have the service manual?
always a great place to start is the wiring diagram!
are you good with electrical and volt meters? as well as test lights?
click here for the tools page
ok you have been there on the oil rodeo...
also check the output sensing in the controller.
it may have loose wires or under crimped or over crimped wires..
making for an no output voltage sense in the gen controller.
that would signal a re start.

you can add an start over ride relay easy.
just place a 125 vac coil relay or a 240 vac coil relay at 30 amp contacts depending on the gen output sense.
inline with the call for start wire going to the small starter relay coil feed.
that way when you have gen output it will not over grind the starter.

the controllers are way to complex these days..
they are not as simple as they used to be and expensive to replace them.
is the generator engine mechanical injected or is it electronic injected?
a lot of the tier 4 or even the tier 5 engines have electronic injection..
and are harder to convert back to basic full relay / switch controls...
we built a board for a late model cat last week for a mining client that was old school conversion.
late model engine on an old piece of equipment.
pricey... but when you are dealing with special equipment like that you can spend some money in an upgrade update!
 

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Discussion Starter #3
sorry late to the party..
do you have the service manual?
always a great place to start is the wiring diagram!
are you good with electrical and volt meters? as well as test lights?
click here for the tools page
ok you have been there on the oil rodeo...
also check the output sensing in the controller.
it may have loose wires or under crimped or over crimped wires..
making for an no output voltage sense in the gen controller.
that would signal a re start.

you can add an start over ride relay easy.
just place a 125 vac coil relay or a 240 vac coil relay at 30 amp contacts depending on the gen output sense.
inline with the call for start wire going to the small starter relay coil feed.
that way when you have gen output it will not over grind the starter.

the controllers are way to complex these days..
they are not as simple as they used to be and expensive to replace them.
is the generator engine mechanical injected or is it electronic injected?
a lot of the tier 4 or even the tier 5 engines have electronic injection..
and are harder to convert back to basic full relay / switch controls...
we built a board for a late model cat last week for a mining client that was old school conversion.
late model engine on an old piece of equipment.
pricey... but when you are dealing with special equipment like that you can spend some money in an upgrade update!
Will be going to the mountain this weekend and checking the sense wire on the board. Now that I know where to look, I'm confident I can track down the issue of why it is not sensing that the generator is making power.
 

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The starter engages after the generator has been running... sounds like a short to the starters signal wire.
 

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Discussion Starter #6
I'm currently at the generator. Started it up with fluke connected to the S15 & S16 leads, at the common lead and power on one leg of the breaker. When it started it was at 320v then went to 168v and starter stoped, then it went to 320v again and starter kicked back on. This all took place within a few seconds and I turned it off.
 
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