Onan Generator Stops Shortly After Start Up

[Liming II]

Hello All,

I have a new to me catamaran with an Onan 9.5 Kw Generator. We went to start it up today and when I checked water outlet and it seemed like the was some black soot coming out with the water from the exhaust. Shortly after that the engine died. The error code I got was for a low AC voltage error. I believe that code was generated by the engine not running at full power due to what I'm thinking may be a clogged fuel filter, hence the black soot in the exhaust. Has anyone else experienced this and am I on the right track? If I'm off base please direct me in another area to look into.

Thanks,

Mike

[dougweibel]

Your diagnosis would not be my first choice of explanation.

When you start your generator leave the main generator breaker on your distribution panel set to off so there is no electrical load on the generator. Watch the generator output voltage after startup. What is it showing? If the generator shuts down with a low voltage alarm and no load connected then unless the engine is running very badly it is unlikely it is because the engine is generating insufficient power.

Come back with more info and to help others help you. What is 'shortly after'? What is the AC voltage doing after startup without a load? Does the generator engine start easily and what does it sound like? Do you have a monitoring panel that will show AC frequency and other info that may be helpful for diagnosis?

[kiwin]

It's almost certainly fuel starvation. So empty tank, blocked line, blocked filter (s) , fuel pump or boost pump leaking or not running, or suction leak somewhere. ...
Rule no 1. with diesel engines...it's almost always the fuel. Rule numbers 2 through 10...
It's still the fuel. Other rules relate to compression, air etc

[GordMay]

RV GENERATOR TROUBLESHOOTING GUIDE
See page 4
➥ https://www.flightsystems.com/pdf/on...ting-guide.pdf

Service Manual
➥ https://www.seapowermarine.com/seapo...ice-Manual.pdf

[Tin Tin]

Is the generator running off same tank as an propulsion engine. Is the propulsion engine blowing any smoke? Are tank fuel valves fully open (including the return)? How long since the generator was last run and how many hours on it? When was last filter change? If unknown change it anyway and bleed the system. if it has an air cleaner, clean the filter. You might have a bigger problem with the generator have a seized bearing, but get the easy stuff out of the way first. I assume you have checked oil and coolant levels.

[Liming II]

Good Morning,

Thanks for all the replies. I'm sorry I don't have more information. My generator does not have an AC voltage readout. The engine started smoothly but within 1-2 mins it "bogged" down, resumed running for a minuet then was running rough and shut down. When I tried to restart it it ran for about 30 seconds, it ran rough then shut down.

I am thinking the issue is fuel, to begin with. Does anyone happen to have a model number for the engine mounted fuel filter on an Onan 9.5 HP e-series MDKBM. The filter on there now I think is European and NAPA could not cross-reference it.

Thanks,

Mike

[Liming II]

I checked the oil and coolant, with fine. The generator was run 2 days prior for about 2 hours, no issues. There is no smoke com ing from the propulsion engines. I will start with the fuel filters. Thanks

[Bent Bugle]

Apart from changing the fuel filter & bleeding, I'd clean (or change) the air filter, obstructions in airflow can cause black smoke & rough running...also could be injector issue...it" a process of elimination..

[Tin Tin]

This is the link to complete parts manual
https://www.seapowermarine.com/seapo...rts-Manual.pdf


Onan 149-2106 there are plenty of cross references for this.

[David Mathis]

Black diesel smoke if often a symptom of incomplete combustion due to insufficient air. The simplest and cheapest check is to remove the air filter and start the engine then put a load on it. Does it run properly? If not, it wasn’t the air filter so it’s probably a fuel issue.

[coopec43]

https://alltroubleshooting.net/onan-...oubleshooting/

https://rvside.com/onan-generator-troubleshooting/

https://www.flightsystems.com/pdf/mo...uick-guide.pdf




Has anyone given you this link?

Onan Generator Starts Then Shuts Down: Troubleshooting The Problem

https://outdoorfact.com/onan-generat...oubleshooting/

[coopec43]

Originally Posted by Liming II

I checked the oil and coolant, with fine. The generator was run 2 days prior for about 2 hours, no issues. There is no smoke com ing from the propulsion engines. I will start with the fuel filters. Thanks

Are you still with us?


Did you get the problem sorted out?