BAC Forum
General Boards => Technical Support => Topic started by: Dave Cunningham on March 29, 2013, 12:11:27 AM
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Hey , is there any onan generator experts out there, I am having problems with my 12.5 diesel, in my 03 .
The generator starts right away, smoking like crazy, and usually dies, if you shut off the breaker on the unit itself, on the third startup it will keep running and the smoking clears up after 30 or 40 seconds, then you can turn the breaker back on and it works ok. I had the generator tuned up when I was in bend a couple of months ago, it was still acting up so I stopped at cummins northwest in Seattle , they diagnosed that it needed a computer control board. Got back to Victoria and ordered anew board from Vancouver ( $1000.00) put it in yesterday ,and guess what, nothing changed, and of course they won't take the board back.
Oh, and when the unit dies the first couple of times it is flashing a code 13, wich is supposed to indicate low output voltage. Also when it is running, you can load it up with everything running in the motorhome and the idle never changes.
Dave
Ps the unit only had 30 hours on it when I got it, it has about 100 now
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does it smoke every time you start it up? What color is the smoke?
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Hi John, yes it does smoke every time, the smoke is pretty blue.
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Blue smoke signifies incomplete combustion. Could be air/fuel moisture, could be carbon deposits, could be improper valve adjustments, worn injectors. Should never see blue smoke so definitely a problem that needs fixing
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I'm not sure if your model has a preheat cycle system. I assume that it is relatively cold where you are going through start ups and wondering if your problem is that the cold start system is just not working. I would ask the Cummings shop that worked on it if you have a preheat system and if that issue was related to the diagnosis of changing of the board. There was a reason they thought the board was bad, if it was not the board, they should know what the other possibilities are that could cause the symptom they were working on, perhaps a bad sensor. The low output error could just be that when cold you are not running on all cylinders until combustion starts evenly. That can cause smoking and rough running also.
When you "load it up" and you say the idle is not changing, I think you mean RPM is not changing. I believe you have a constant speed generator and at 1800RPM it produces 120V 60 cycles. It increases and decreases throttle based on load to maintain that rpm which is normal. It must be running right to do so and when yours is cold it is not. Not sure this is your issue but it is worth understanding the cold start system on your generator and see if it is operating properly....
Later Ed
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We have the same generator and ours even on a cold start (we're in Minnesota) it doesn't run blue. We will get some white smoke if we haven't run it for over a month.
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thanks guys, Ed, you are correct in assuming i meant the rpm, and that is a good point about the constant rpm, someone suggested that to me , but every other generator i have had always an rpm increase as the load was increased. it is not actually that cold here right now , yesterday when i tried to start the unit it was about 60 degrees out, i think you may be on to something with the cold start system. its tough here on vancouver island, we don't have a cummins onan shop, the closest one is in vancouver, the local rv guys are useless, and the 45' sapphire costs about $ 250.00 each way on the ferry, oh well might have to bite the bullet, or wait till i go south next.
Dave
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The generators that increase and decrease RPM like the 7.5K-8K Onan and the Honda generators that end in (I) like the 3000I use inverters to maintain voltage and sine wave AC output. That type can vary the RPM as the load demands more or less energy. Most of he others are either 1800RPM or 3600 constant RPM generators. The speed of the constant RPM is dictated by the number of poles in the generator. Sometimes what you hear in terms of noise level increasing or decreasing may be interpreted as RPM but it may just be throttle levels at the given constant RPM. More generators are migrating to electronic inverters.
The 12.5KW Onan mentioned an automatic timed glow plug cold start system. You may be able to look for the glow plugs at the cylinder head, trace the wires and see if you can see 12V being applied for 15 to 30 seconds or so when cold. They look like a small spark plug. Another way to check would be a clamp on DC amp probe on the + feed wire to the generator. When you press the start there should be a delay when the fuel pump comes on and a current draw should be going to the glow plugs at the same time. I would guess it is in the 25 to 50 amp range. If you are not seeing a heavy load before the starter is activated then that system is not working. Another check would be to measure the ohms of each glow plug if the harness can be disconnected. They are likely less than an ohm and should have similar readings. This would only tell you that the glow plug is good, but does not tell you if the control circuit is working properly.
Later Ed
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Thanks Ed, I will try those tests tomorrow .you would think Cummins in Seattle might have tried some of these things before they sent me on my way, telling me I need a $1000.00 computer. :(
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I have similar problem with my Onan 10KW on a 2007 Patriot Thunder. The generator always starts and runs for 8 seconds and shuts down with a code 13. I do not have the smoking problem but the generator always shuts down. I had the same problem last year and Lazy Days replaced the Stator, control card and I think the voltage Regulator. I have an appointment at Lazy Days in April unless someone comes up with an answer to these two similar problems.
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Cummins has a "Coach Care" system. http://www.funroads.com/coachcare/ Check the list and map towards the bottom.
It might make sense that they have a higher experience and training level for the Onan units we have in our motorhomes. The Seattle Cummins shop is not on that list.
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thanks Bill, I will check that out
Dave
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I did not see in the posts anything about primimg. You are priming it for at least a minute... especially if it has not been run for several days or weeks?
Over the Winter I tried to run my generator for at least an hour every three or four weeks. It would start, then die after a minute or so. This would happen four or five times. Then I read the manual and saw where I should be priming it for at least a minute before starting it. After that lesson, it would almost always start and remain running without dieing... and this was when it was near the freezing point... from 25 F to 35 F.
My generator has just over 600 hours. I am told it should have a valve adjustment at about 1,000 hours, then it's good for (hopefully) 100,000 hours... assuming regular service maintenance.
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David,
what do you mean by priming , when i start the generator, i hold the switch as it preheats and it just starts when it is ready, how do you prime it,
now the problem has gotten worse, it used to run forever, once it was warmed up , but now dies after about 20 minutes of running.
Dave
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Here is what the manual says.
PRIMING THE FUEL SYSTEM
The fuel system should be primed after replacing the fuel filter or running the genset out of fuel. To prime the fuel system hold the control switch down in its Stop position for at least 1 minute.
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Our diesel generator in our boat used to run for a minute it two or even 15 minutes or so and then quit it turned out we had air in the fuel line. So every year when we put the boat back into the water we would bleed the line at the lift pump. At first we didn't know what the problem was and we burned out the lift pump. Diesel generators a famous for air in fuel problems make sure your tank is full when you store it and bleed the fuel line
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Yes... it's a 3-way switch that is spring loaded to rest in the middle position (its off position). Pushing and holding the rocking switch in the down position accomplishes the priming operation. Hold it in the down position for at least one minute. If everything is off and quiet, then you can hear the fuel pump working. Then push and hold the rocking switch to the up position to start the generator. With my generator, I thought pushing it to the up position actuated glow plugs initially because there was a several second delay before the generator starter motor turned over and started the engine.
The rocking switch in my coach is located on the left dash just under the Kenwood. I have 5 switches there lined up horizontally. From left to right the 5 switches are DRIVING LIGHTS, DOCK LTS, START BOOST, GEN START, and ATC. The GEN START switch has a horizontal light bar built into its lower half, I assume, to signify you have actuated it.
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Dave,
Do you get a code when it shuts down? Is it very abrupt like you would get when you press the stop switch? Your genset is at an age where one would expect the cooling fan belt to have streched and aged. Hours do not matter so much here with this issue. I characterized my genset using an IR gun with the failing belt and with the new belt. From an earlier post....
On my genset with a good belt I read 118F on the radiator face, 144F on the oil pan, and 187F high on the block. Your numbers will vary some from mine but they should be somewhat close. With a slipping belt my radiator reached 216F, oil pan 207F, and the block was 215F. You will not hear any squeal from a slipping belt in this application.
I'm not saying this is your issue but the length of run time before shut down is about right as is the age of your belt. This problem is easy to sort out with an IR gun and the numbers listed above. BTW running with the front cover open for more than a minute or so should be avoided given the enclosure is required to move air through the radiator for cooling.
Later Ed
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Hmmm, I am going to try that, a diesel mechanic I talked to today said it sounded like I have air in the fuel line.
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David/Ed,
For some reason didn't see your post before my last reply, thanks for those ideas, I am going to get right into this thing in the next few days, I was busy all weekend finishing all the paint repairs at my shop, and other than the ice maker, that hasn't arrived yet, thagenerator is my last issue( unless something else broke since I drove it home this afternoon)
Dave
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If you suspect air in the system usually the diagnostic tool is a sight glass worked into the fuel line on the engine side of the filters etc. If you see air passing through with the fuel you can then tighten fittings, change filters etc until the air source is found and resolved. Air leaks would tend to make it not start. Your running 15 minutes and dieing would seem to not fit well for an air leak. I'm not sure of that, just a guess. If air was getting in it would seem that the engine would run rough as it dies. If it is an overheat or some parameter the computer system monitors for, when the safety systems shut the engine down it would be like hitting the stop switch with a sharp cut off. Usually a code is transmitted with that type shut down. This site has sight glass fittings available.
https://secure.k9bytes.net/~monacoto/cgi-bin/k9bytes.pl?command=listitems&pos=0&type=search&search=cummfsy
Later Ed
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Ed I disagree. The first thing the mechanic said when I told him the issue with our generator was air in the line there are so many places for it to come in including a microscopic hole in the line itself including all the fittings. Once we started keeping the tank full and bleeding the line at the lift pump we solved the problem
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Have you looked at the switch on the generator itself to see if it is showing a fault code? The codes do not show on the remote start switch on our Onan.
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As I mentioned in the first post, it does show a 13 code, when you first try to start it, but I did not check for a code after it died the last time , I will have to check that
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John,
As I think about it, if there was an air leak it would allow the fuel line to drain back to the tank, therefor the hard starting and the need to prerun the pump. I'm not sure you would get it to start and die 15 minutes later with an air leak unless the small filter held enough fuel for a 15 minute run. For my generator I never pre run the pump and even a month later it goes through the start sequence, does its short delay preheat, starts the fuel pump and then just fires up. I have never had to do anything special. I think that assures that I do not have any air leak....
I guess the only way for Dave to know for sure is a sight glass. I had my older Beaver die one day and had to get towed into a a Cat dealer in Denver and they installed a sight glass at the engine fuel inlet and saw air in the fuel stream. We worked it back to the line from the tank and saw no air in the fuel stream. The secondary filter gasket was leaking and ended up being a Cat Part defect. They treated me kindly given that. It had gotten cold and the gasket was already marginal in a compromise location on the filter interface to the housing. Cat bean counters had them redesign three PN filter designs into one offering which turned out to be the bad compromise unit for me. The original filter had two well spaced O rings and the new PN had one that lined up right at edge of the flat gasket face on the housing.....upsetting when the bean counters are in charge.
The sight glass is the definitive way to rule this issue out or to diagnose the problem source but it does have to be plumbed in to use it.
Later Ed
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The other issue it could be is with the lift pump overheating as a result of air in the line. Ours ran for 15 minutes and then quit just like Dave's. There should be a bleed screw on the lift pump. It's easy to bleed by yourself. If that doesn't solve it have the lift pump tested. We found that we had overheated it and killed it before we found the air leak.
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I am waiting for a call today from Cummins in Vancouver , they are trying to help me out since I spent all that money on the board there, they have one of thier rv guys looking at the problem, I am going to gather his suggestions , combine them with the ones you guys have given me , and see if I can figure this thing out.
John, I am assuming the lift pump is part of the generator itself? is it easy to get at?
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Dave,
We have over 3000 hrs on our 10KW unit (many summers of nothing but dry camping near the Grand Canyon) and have experienced similar smoking and shutdown issues. We found that Ken Vick at the Rocky Mountain Cummins shop in Albuquerque NM was a virtual whiz at troubleshooting and resolving our issues over the years. A couple times, when this issue reappeared, Ken was able to diagnose a restriction in the fresh air intake system ... due to dry camping on our wilderness property, wood rats and field mice had been "sucked" into the intake. Upon "exhuming" the dessicated carcasses, the generator returned to good operating condition.
If your travels ever take you to Albuquerque (maybe for the Baloon FIesta??) and you are still seeing the problem, give the shop a chance ... their number is (505) 247-2441.
Good luck and safe travels.
Glenn
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Thanks, Glen!
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Just had a tech from Cummins spend 2.5 hours trying to diagnose the generator issue, I had it all set up for him to work on and the first thing he did was pull the air cleaner element, on the initial startup it fired , pumped out a bit of smoke for about 3 seconds and ran perfectly, I know your thinking " Dave , I thought you said you just had it serviced by beaver coach in Bend, " which I did, apparently changing the air filter is not part of the service . the other problem that he detected is that I am only getting about 9 volts to the unit on startup, ( it has always cranked a little slow ) and he said that there are relays on the board too control the glow plugs , controller ect. that need good voltage to engage, checked all the connections at the unit and they all seem fine, I need to see how the positive lead is routed to the batteries and find out why there is a voltage drop, but it seems like the air cleaner was playing a big part in the situation. So after a $1000.00 control board and $ 450.00 in mobile service charges, I will replace the $ 30.00 air cleaner and see what happens.
Dave
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Even Jiffy Lube checks your air filter when giving an oil change. They will show you the air filter and either recommend a replacement or not. In any case, even Jiffy Lube checks the air filter and notifies you of their recommendation. BCS needs a boot in the rear on this one.
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Got to the coach this morning, installed the new air filter, fired it up, and after a 2 second puff of smoke it purred like a kitten, oh by the way I got the revised bill via email from Cummins in Vancouver, the service call didn't cost $450.00 it cost $890. With tax, $2000.00 to fix a bad air filter, I am going to be making some phone calls on Monday, that's for sure.
One more problem though , as I mentioned before, after about 45 minutes to an hour, the unit still dies, checked the code this time and it was over temperature, Ed , in an earlier post you mentioned the fan belt possibly slipping, I took a quick look in there and the rad in on the bottom of the unit in the front, can't see how it could have a mechanical fan, just wondered if anyone had any ideas as to why it might be overheating. The coolant is topped right up.
Dave
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Dave,
The squirrel cage fan is on the right end of the genset and driven by a belt. The design uses the cabinet enclosure as ductwork so the fan is not near the radiator.
There is a sensor that could be giving false readings and causing shut down or it could be the belt, thermostat, or the water pump. Water pumps rarely go on these units and the thermostats are not problematic. You need to IR gun the block and radiator and use the readings that I provided to see if it is a true overheat situation. Fan bolts onto the aluminum hub in the attached photo...Photo of the fan and one of the sensor just in case your IR gun finds that the temps are normal and you are getting an overheat shut down. You can change the belt with the unit in place but it is not easy. The back cover bolts need an Ichabod Crane arm reach to get to them... my guess is the fan belt is stretched due to the aging of the materials.
Glad the air cleaner solved the engine issue, just one issue left to go....
Later Ed
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Thanks Ed, now I get it , I can see that changing the belt, must be real fun while the unit is still in the coach, I am definitely going to work through this problem myself, I can't afford any more help from Cummins. Sounds like I have a good excuse to go buy one of those cool IR guns.
Dave
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The IR guns are inexpensive and once you have good data on your unit you will know what the "normal" is when you run into issues.
You have to get the top cover off and the right end cover off to do the job. It is not very involved just time consuming due to the position of things. You may want to precheck that the tools on hand swivel and get to the bolt heads in various positions that you need to get to. I used a gearwrench on some and a rachet on others. You cannot see it in the photo but there is an alternator towards the back and that is the unit that swivels to tighten the belt. I found that I could work a clamp on things in a way to swivel the alternator incrementally, and hold it, to get the tension where I wanted it before tightening things down. That was a big help. The black crap that you see on the parts is the aged belt breaking down. I only had 180 hours or so on the generator so none of this is wear use just age.
If I had my choice I would have replaced the back top cover bolts with something that were quick release by pulling but I did not get to it...just would make that job or any generator job almost tolerable in the future.
It is too bad that the technical folks missed the obvious on your unit and still charged you a lot of money. Hope you get some satisfaction (like in the Rolling Stones song)...
Later Ed
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thanks for the info Ed, should be quite helpful, I will let you know how I make out
dave