Generator won’t start

[Flymitch]

Onan Geni.
Hit start switch for 20 seconds, it does a split second crank then nothing.
Pulled starter.
Jumped with cables, it works fine.
Rotated engine with wrench, it rotates.

Put back together, same issue.

Took boat out for 2 hrs, got back to doc, started like nothing was ever wrong.

Let boat sit for one week with full time battery chargers on main bats, and still give me the Ugh at 20 second., no start.

Any clues why?
Possibly a corroded power or ground cable?

Thanks for all opinions.

Merry Christmas!

[madhatter1]

No crank or no start while cranking?

[Pascal]

Yeah I would check the wiring between the batteries and the starter especially if it starts with jumpers.

How old is the battery? What size battery and what size genny?

I ve had a similar occasional issue with the Ohno 27.5s on the boat I run. Sometimes when I press start, it will go they it’s sequence cranks for a split second and stops. Usually it starts on the second try. Once or twice I had to use a jumping pack. In my case I suspect a group 31 is a bit light for a 27.5 but no room to switch to a 4D

[Flymitch]

I have to look now that I am suspecting the battery OR possibly ground or power connection, corrosion. I will find the size, took some photos last time I was in the bilge pulling it apart.

Thanks for opinions.

Mitch

[Flymitch]

4962133 9 kw.

[bigbill]

Yeah I would check the wiring between the batteries and the starter especially if it starts with jumpers.

How old is the battery? What size battery and what size genny?

I ve had a similar occasional issue with the Ohno 27.5s on the boat I run. Sometimes when I press start, it will go they it’s sequence cranks for a split second and stops. Usually it starts on the second try. Once or twice I had to use a jumping pack. In my case I suspect a group 31 is a bit light for a 27.5 but no room to switch to a 4D

84 foot boat and no room to up size a battery?

[JLR]

Check the start solenoid plunger that shuts off the fuel.

[Pascal]

84 foot boat and no room to up size a battery?

Not without Major surgery...

[bigbill]

can you move it to another spot close by? maybe too small of cables on the existing battery... i used a group 31 for a while in my bertram to start a cummins 5.9 300 hp till i upsized to an 8d per engine.

[Boatsb]

FLYMITCH.

start simple.

Check the battery and cables. If there is even a slight doubt replace them.

I use grp 31 batteries the time to start 5.9 and 8.3 Cummins. The generator is probably less than 30 hp and if all in the system is done right there's usually no problems.

The usual issues I find are.

1) Weak battery. A good pulse tester is a must.
2) Poorly made cables or wrong size cables. Soldering the ends is a bad thing.. proper crimps are square or hex, hold hundreds of pounds of pull force and have glue lined shrink to protect them.
3) Bad switch or fuse on the line causing voltage drop.