Generator problems

G

guitarfish

New Member
Oct 6, 2010
26
Southern California
Boat Info
1990 sea ray 270 da sundancer
Engines
mercruiser w/bravo III
I have a 1990 Sea Ray 270 DA /Sundancer that has an Onan 3.0 First Mate Generator. ( I assume it came with the boat originally). It worked okay until recently. The last couple of times I ran it, it shut off after about 15 minutes. My first suspicion was overheating, but it seems to be drawing a normal amount of water. Then the last time I tried to use it, the switch would turn the generator on, but the generator would not stay on unless I held the switch in the "on" position. This was the same whether I used the switch on the instrument panel in the cabin, or on the generator itself. Just wondering if I have an electrical problem, overheating problem, both, or neither?!?!? Any suggestions out there in CSR-land?? Thanks Pete (guitarfish) :huh:
After reading a couple of replies, I'm wondering why my generator would not start at all, if it's cold and hasn't been run?!?! In other words, why would the switch all of sudden not be able to start the generator without holding the switch down, even with the generator being cold??
 
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Sounds like the oil pressure switch is bad. I think it gets bypassed when you hold the switch and when you let it go if it dosen't see oil pressure it will shut down. I had one of these one my last boat. I had a few problems but mostly was good. My gen would shut down after extended runs which turned out to be a bad fuel pump. Another time the t-stat got stuck closed and did not shut down. Could not get a t-stat so I took it out. And the last problem was the choke spring fell apart. Never did get that quite right after that. Parts are now hard to find so good luck. How many hours do you have on yours?
 
I have the same genny and it was shutting down after about 10 minutes at the end of last season. I just put in a new impeller hoping maybe it had a slight lack of water flow ( old impeller looked okay but did have a "set" in the vanes.
I have not splashed yet to start troubleshooting it. I have the original manuals if you need part numbers etc. I know these units have three "shut down" sensors.
1 - oil pressure
2 - engine temp
3 - exhaust temp
 
To Quint4 from guitarfish re: Gen probs: thanks for the input; I could probably use any part numbers if you have them handy; I may have the manual, however. Thanks again; Pete (guitarfish)
 
I have the same MJAB Onan in my 96 290. It does nothing but turn over. No spark No fuel.

I don't even know where to start.
 
I have the same noisy little ba$tard on my boat as well:

Part numbers are as follows:

1. Item #20 P/N:309-0002 Switch, High Engine temp (Located on cylinder block assembly)
2. Item # 8 P/N: 309-0484 Switch, High Exhaust Temp (Located on exhaust assembly)
3. Item # 5 P/N: 309-0322 Switch, Low Oil Pressure ( Located on the clyinder Block assembly)

Try Unpluging the wires for the sensors and see if it stays running, Thats what I did to troubleshoot which sensor was causing the problems, mine was the high exhaust gas temp sensor.

FYI: All sensor/switches go to ground for cut out, so unplugging them would keep them from grounding and shutting the unit down...Use caution regarding the oil pressure, if it runs without pressure...your toast! I'm sure you knew that though. Check the oil level as well!
Good Luck!
 
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Here is the troubleshooting page of my manual. Shore are you getting 12v to the fuel pump?

gen2.jpg
 
No spark would be cause by one of those sensors grounding out the ignition circuit. or possibly a bad ignition coil.
 
I have no idea, this is my 1st gen set. All I know is it cranks all day long off the inside switch or the gen set switch. I pulled the plug and no spark while cranking. I tried starting fluid to bypass the fuel issue and nothing still.

It's like it's not getting any electrical beyond letting the starter spin.

Also, it's still in the boat.
 
From guitarfish, re: my original post re: Generator problems; thanks to all, for all of your input. Unless I missed something, I'm still in the dark as far as why my generator all of a sudden, won't even start without actually holding down the "start" switch?!?!? :huh:
 
Your not listenting....IF!!! One of your sensors is grounding out YOU WILL GET NO SPARK! Once again, try unplugging your sensors and attempt to start again. If it still wont start, check your DC control fuse, it acts as an emergency stop, and if its blown, it will cut out the genset. (The top fuse of the three fuses)


You are not telling us what actions you are taking to eliminate problems.

Also, what are you usuing to test spark? An indicator or are you just holding the plug to ground?

The more details you give the better we can help.
 
plug to ground to test. then I tried starting fluid just to see if it would fire at all. Nothing.

I'll play with the sensors.
 
guitarfish-

This is YOUR thread originally, and others have hijacked it. You need the Onan service manual for proper diagnosis of your electrical problem. Good luck!
 
Scupper Guppy said:
guitarfish-

This is YOUR thread originally, and others have hijacked it. You need the Onan service manual for proper diagnosis of your electrical problem. Good luck!
Click to expand...

Not sure how that happened; :smt021glad someone noticed?!?!? :huh: I'll just have to pour thru the manual and see what I can figure out. :smt100 I'm only marginally mechanically inclined, but I'm tired of paying marine mechanics $150 per hour to figure this stuff out, and only sometimes fixing the problem!! (My apologies in advance to all you marine mechanics out there!!) - - but I'm going broke trying to keep all the "bells and whistles" on this boat operating!! I'm sure I'll be posting another problem soon!!! :smt024Stay safe on the water everyone!!! (Gotta love all these goofy icons?!?!?)
 
Gensets have a similar wiring arrangement brand to brand.

If the your fluids are topped up including coolant, and safety sensors check okay, and you can test them (Do a simple continuity test when cold as current should pass across the poles. If one is bad you'll find it and replace.), and you are sure the raw water is moving adequately, you have a gremlin.

Still not starting? Check the alternator circuit. Yes, 90% of the units out there have that cheeky bastard is tied in to the shut down circuit, if it fails, the whole system shuts down and there is no over ride.

Check the remote starting switch to make sure it is functioning. If it's okay then check the stupid electrical connecting block in the starting circuit, probably behind the Main breaker panel. I had mine jiggle loose and half the boat was not functioing inc. the genset and one main engine starter! I wire tied it (modification upgrade) back together, and shazaam, the gremlins went away.

Your service manual should have a wiring diagram for the safety and starting system.

My last PITA genset failure was mind bending, and after about 300 in replaced parts I found I was just throwing money at it, I found the real problem after careful observation. On the back side of the genset is a sensor for over heat which is driven off exhaust gas in the riser. It's contact poles stick out proud, for reasons I won't get in to the sound shield was vibrating and making intermittent contact and shorting the whole safety cut off system down ... the Insulator boot had wiggled out of the way exposing a pole. The boot had been wired tied at the yard after some non related work was completed requiring the genny to be shifted for access.

Their use of wire ties was in a nonsensical way which let the boot slip off the sensor.

I realize you have a gasser genny, but the problem is probably not usual like low coolant, because at the onset it would start cold at the genny but die when the circuit at the genset was used, but not start at the control panel.

Grab your multi meter and go after it. If nothing seems to be the cause, if the alternator is in the shutdown circuit, take the alternator to a shop and have it tested.
 
Asureyez said:
Gensets have a similar wiring arrangement brand to brand.

If the your fluids are topped up including coolant, and safety sensors check okay, and you can test them (Do a simple continuity test when cold as current should pass across the poles. If one is bad you'll find it and replace.), and you are sure the raw water is moving adequately, you have a gremlin.

Still not starting? Check the alternator circuit. Yes, 90% of the units out there have that cheeky bastard is tied in to the shut down circuit, if it fails, the whole system shuts down and there is no over ride.

Check the remote starting switch to make sure it is functioning. If it's okay then check the stupid electrical connecting block in the starting circuit, probably behind the Main breaker panel. I had mine jiggle loose and half the boat was not functioing inc. the genset and one main engine starter! I wire tied it (modification upgrade) back together, and shazaam, the gremlins went away.

Your service manual should have a wiring diagram for the safety and starting system.

My last PITA genset failure was mind bending, and after about 300 in replaced parts I found I was just throwing money at it, I found the real problem after careful observation. On the back side of the genset is a sensor for over heat which is driven off exhaust gas in the riser. It's contact poles stick out proud, for reasons I won't get in to the sound shield was vibrating and making intermittent contact and shorting the whole safety cut off system down ... the Insulator boot had wiggled out of the way exposing a pole. The boot had been wired tied at the yard after some non related work was completed requiring the genny to be shifted for access.

Their use of wire ties was in a nonsensical way which let the boot slip off the sensor.

I realize you have a gasser genny, but the problem is probably not usual like low coolant, because at the onset it would start cold at the genny but die when the circuit at the genset was used, but not start at the control panel.

Grab your multi meter and go after it. If nothing seems to be the cause, if the alternator is in the shutdown circuit, take the alternator to a shop and have it tested.
Click to expand...



Thanks for all the info! I'll have to get to work; thanks again; Pete/guitarfish
 
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