Onan Gen set

[wshelton]

I have a 43 Hatt DC with a 7.5 Onan diesel genset. For some unknown reason the unit will not start. I have an electricl box on the unit that has a fuse, breaker, amp meter, pre-heat switch and a 3 way start/stop switch. I have the same switch set up on the eletrical panel in the saloon. Problem is noted. On the box on the genset the amp meter is pegged down -5 amps. If the genset is running of course it shows a + setting. This reading is without the genset running. I turned the battery selecter switch off to remove 12 volt power to the unit. When I turn 12 volt switch back on, this smae - reading on the meter. Of course I cannot start the genset/ go to start position I get nothing. I am conerned of couse this - amp reading on the meter when not in use and 12 volt power on. Fuse is good and breaker appears to be ok. Big question is when 12 volt power on why this - amp reading on the meter???? Of course cannot run gentset either.

Solenoide seems okay too as it will cleck back and forth if I push in breaker and apply power to the unit and attemp to start unit with switch. I have monkeyed around with these to make solenoide move, FWIW

Ideas please or call: Will Shelton 901-680-7798.

 

[REBrueckner]

(1)So with 12 volt power supplied to the genny, you get a negative 5 amp reading indicating discharge?

(2)And when you toggle to start position nothing happens....genny does not turn over??

(3) What solenoid clicks...the start solenoid that activates the starter??

Sounds like maybe a relay is improperly stuck in the run position....but that is inconsistent with (3). And (3) seems inconsistent with (1).

If you have the Onan owners manual, it should have the start sequence explained....each step that the genny takes during the start cycle.....that's the place to start...but maybe someone here has worked on one recently and remembers what takes place.

 

[RTyler]

I've had that problem before. I'll bet your centrifugal switch is stuck. On mine it's located just to the right of the fuel filter ( lower right hand corner ).

Robert

 

[stilespb]

There is also a high temp cut out switch usually mounted exterior to the cylinder block on the generator end just below the head level. The thing is made out of plastic with a sheet metal base and a bimetalic switch inside that opens when hot. Wire lead up to it are screw mounted to it.

I have broken this thing moving around the generator room because it is very light weight. If that it is the problem, starter will crank it over but it will not start because the stop solenoid circuit is open and the fuel is shut off.

 

[Trojan]

Will, check your safety shutdown switches I think there are two, Low oil and over temp. I also think your meter is OK. The negative indication is only a zero voltage rest point. Either switch will keep the unit from cranking. It's the first thing check.There will be no voltage through the unit until the safety switches are clear. These switches are tied back to the relays in the box. The over voltage control is next to look at.

BILL

 

[Nonchalant1]

Just a thought - If it's like the MDJF, it has a low oil pressure switch that shuts off starting when it has been tripped. If so, there is a "reset" button for it, so it can be started again. That switch is operated by a heater coil around a metal release and when the coil heats up, it throws the switch and shuts the engine down and won't restart. The coil draws current to heat it up until it is reset. Maybe that's your draw?

Doug

 

[Canuck Dennis]

always check simple things first.....

Is the 12 v ground strap and connection clean and bright on the genny ?

Does the starter solonoid click but not engage ?

Is the Battery fully up ??

Check the red reset button, sometimes this just burns out in the open position, (90.00 item).

Check HT exhaust switch if intalled,

Check High Cyl Head and Low oil safetys; ( temporarily disconnect) one at a time.

Check contact points if faulty.

Will most likely be one of the above....

Be aware that parts for those control boxes are becoming obsolete and a new box (450.00) will be the next step after they discontinue the red emerg. stop switch.

Good luck....

 

[Bob Bradley]

And if you get sick of screwing around with the damn thing after a couple years like I did, just install a new Norpro 9kW for about $6k and forget about it.

I do still have MDJE parts if you need any.

 

[Bill Allen]

Don't know what it's called but theres a rod that gets pulled in by a solinoid mine (before I got rid of it) wouldn't pull in. Push it up when you engage the switch on the set and see what happens

 

[wshelton]

Many thanks for all of your responses.

After calling three mechanics for an appointment and all no shows I thought I owed it to myself to at least once again crawl down into the sauna for another professional look.

After pulling out my lower back and burning my right forearm on the engine I settled comfortably down on the battery boxes bending my neck about 90 degrees out of whack to have a good look at this beast.

Here is exactly what I did. I first did inform the wife I did not call her and I was okay and just fine. That what I said was for her to please go find my tennis racket so we could play tennis later knowing this search would require her to leave the boat for a while.

I then unscrewed the fuse and took it out to see if it was good (no meter of course) and while out attempted to start the engine. To my surprise the engine turned over fine but would not run. Did notice a solenoid moving back and forth. Of course do not know what it went to. So I monkeyed with it moving it back and forth a few times while burning my other arm on the other engine. Satisfied this burn was no worse then the other arm I hit the switch again. The engine would turn over fine again and this time the solenoid appeared to be in a different position. About this time the wife returned from her futile attempt to locate my racket and upon boarding the boat the listing cause me to loose the fuse I had taken out to eyeball. While the wife was looking for the replacement fuses she did however locate the mussel relaxers which I suggested would work just fine and I ate three of those because it was impossible to sip any liquids while in the position I currently was in.

Apparently gravity has something to do with this I assume. As luck would have it I found the fuse along with an old cell phone and a 9/16 socket.

Assuming the fuse was okay now that it was lubed up nicely with oily bilge water I screwed it back in although it took me about 30 minutes to find the screw cap it fit in.

I then gave the Onan another thorough eye examination and was satisfied I was not going to be caught in the fly wheel and/or electrocuted should this SOB fire off when I hit the switch.

The SOB fired right off and has run just fine.

Now all I have left to do is go buy at least two new batteries and another tennis racket because the inverter carried us through the weekend up to this point.

Thanks to all of you who responded. I think all the responses got to the root of the problem.

 

[SportFishCruising]

LOL..... that sounds like the typical manner in which I tackle my chores.
I can relate my man.... good luck in your future endevours.
PS... thanks for the funny and probably totally honest follow-up.

 

[Nonchalant1]

Great post! I love it when screwing around with something triumphs over these mechanical beasts. BTW - is "mussel relaxer" something you use to get clams and oysters to open up, or does it just put them at ease?

Doug

 

[wshelton]

I can not spel and spel checker does not katch such mistakes.

 

[REBrueckner]

Hilarious story, happy temporary ending....I'm gathering you don't know what was wrong so unless it was something stuck from lack of use, be ready for a repeat....