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Discussion Starter #1
Okay, I am back to the main machine "The Ghost" while we don't have any snow in the forecast to need the blower machine. Soonest will be a slight chance on Thursday, probably mostly rain.

So, I have an ongoing issue with The Ghost. I have done some searches on the forum and found some similar issues with other machines but didn't see anything on the Onan engines. It takes a while and usually a full charge to start and then it promptly dies. It will eventually start and runs fine but if I shut it down and sits for even a short period of time, a few minutes, it takes a while to start again. With the other machines I read about (James even commented on one!) it was attributed to a possible crack in the fuel line which would allow for air to enter the system and allow the fuel to drain back into the tank. I replaced the fuel filter about a month ago. It was a clear cartridge style and you could see quite a bit of stuff in there. The fuel tank is plastic so I doubt there is any rust in there to flake off and travel up the fuel line.

Questions:
Is this a common thing? I don't remember changing the fuel line on this tractor although I did on one of the machines we have. I should keep a log on what I do to each machine (a paper copy would last longer than my memory). Is there other things that would cause this to happen? As stated in one of the other posts I don't smell gas while trying to start the machine, although once in a while it does backfire while trying to start. Other ideas that were suggested in the other thread: add a check valve at the tank or add a shutoff valve near the fuel filter. Is there something I need to be concerned about with integral fuel pump on the engine?
 

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Make Better Mowers
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What's the condition of the fuel pump? A bad diaphragm could cause issues. Or, perhaps, a bad gasket.
 

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Discussion Starter #3
I have never taken the fuel pump apart. Not sure I want to if I don't need to. Is this a common problem on the Onan engines?
 

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No idea. Never had an Onan. I was just "feeling" your symptoms. Any air intake or pumping air could create your symptoms. Like so many posters, I'm simply throwing out what I think might be suspect.
 

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I have never taken the fuel pump apart. Not sure I want to if I don't need to. Is this a common problem on the Onan engines?
I'm not an expert but replacing this fuel pump diaphragm cured my starting/running issues on my 78 GT/18 Onan. I have seen numerous posts here about this diaphragm. I'm not sure how to check it other than open the fuel pump and visually inspect it. If I recall correctly the diaphragm is super thin rubbery material and it can lose it's elasticity and also get pinholes in it. If yours hasn't been replaced before it's one of those relatively easy things to just go ahead and do considering the age of the engine.

You should be able to google your engine model number and find pictures of the carb and diaphragm.
 

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Discussion Starter #6
I am at a total loss. The last time the tractor was driven was last Thursday by Elsimonito. Last night I thought I would give it a go and see how she reacted. She started right up and ran fine. Tonight I tried again with the same result. She fired right up and continued to run.

So I guess I don't really have a problem.
 

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Cranky Motorsports
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you can take the fuel pump apart, and soak the rubber diaphragm in oil over night then reassemble. If it is dried out a bit that usually helps. The rubber lines they sell these days is pretty crappy, I have seen line harden up within a year or two and warrant replacing. If you ever tried any type of vinly lines, they harden up much faster and even with clamps will leak air or fuel pressure off very quickly.

So what I usually do if I am having issues, replace all the fuel line from the tank to the carb with fresh good quality rubber line. I have been buying Continenetal brand from my hardware store, and have had good luck with it so far.

Make sure you put hose clamps on all the connections. Use a low suction sintered bronze fuel filter which reduces the amount of suction needed.

If the pressure still bleeds off, the pump could be getting weak- however, it should not drain your fuel bowl of gas when sitting, it will merely drop pressure in the line, and the filter may empty out.

If thats the case, soaking the diaphragm in oil will help the pump keep suction.

If all that fails, you can switch to a briggs style pulse pump and just use it in place of the onan one, and those pump way better
 

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Discussion Starter #8
On to another trial with this. It doesn't look like I am drain fuel back into the tank. I can see a slight air bubble in the filter no matter when I look (after it sat for days, while running or right after it dies). What is perplexing to me is that it takes a full charge to start and doesn't usually start right up, no matter the temp. Then at random it will sputter and die as if it ran out of fuel. Sometimes when this happens it will start right up (if I am close to the garage). Other times it won't start at all (if I am at the end of the driveway or down the road plowing for a neighbor). Last year I was thinking it was the charging system so I disconnected the lights so they wouldn't draw power (I don't think it has made a difference).

In the next day or two I will be trying GT-80's suggestion of tearing the pump down and checking it out. Although I can't see how it would be making a difference like I am seeing. There have been times she will run for an hour or more before she quits and other times it is only a few minutes. Monday while pushing 14" of snow from Sunday I got about half my driveway done in about 45 minutes before she quit (at the bottom of the driveway) and even after leaving the charger on for an hour she refused to start. My son helped me tow it back to the garage. She hasn't started in the two or three times I have tried since then.

Another thing I am going to check will be the plugs just to see how they look. I don't remember when I changed them last. The oil is clean and topped off. The fuel is full and fresh.

Any other ideas people have? This is my 18/6 with an Onan engine in it.

Again, thanks for all the help with these two machines I have. I have no idea how you guys keep a whole herd of these things running.
 

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The gas cap vent isn't clogged is it ?...that can let it get air locked and refuse to start or starve for fuel ..I'd also check for spark right after it quits,it might be a coil or condensor failing (if it has points)...
 

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Discussion Starter #10
I'm quite sure the cap vents more than enough. The clear plastic cap over the fill indication is long gone so there should be plenty of venting going on.
What is the easiest or best way to check for spark when it dies?
 

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You can use a spark tester,or just another spark plug with a real wide gap as a tester..
Put the plug wire on the tester and ground the other side of the tester and crank it over--you should get a healthy "snappy" blue spark that will jump a gap of at least 3/16" easily if the coil,points and condensor are working properly..sometimes a condensor will crap out intermittently and kill spark,then magically come back to life the next time you go to start it up..

You can make a crude spark tester out of a piece of wood or plastic by making a hole about 1" diameter in it and putting two screws in it ,that face each other in the hole,leaving about 1/4" gap apart,and hook one screw to the spark plug wire and ground the other screw...
 

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Discussion Starter #12
I dug into it tonight. I got the filter off and then got the cover off the pump. Here are some pics. I haven't been able to find a hole in the diaphragm. So I think it is good. There is one concern with the center piece to the pump. At the top there is a small chip on the carb side. I can't imagine this being the cause of my problem. What are people's thoughts?
 

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Cranky Motorsports
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tough to say from the pics, but if you pull the top off the carb, does it squirt gas when you are cranking it over? If you pull the top off the carb, is the bowl full of gas, or almost empty?

I would say oil the diaphragm, put the pump back together, and see if it squirts out the top of the carb when the top is off. Also, do you have a foam float in the carb or brass? If it has a foam float, it could be randomly swelling up and getting caught on the sides of the carb not allowing it to fill. Foam floats cause a lot of weird problems. Also, nine times out of ten, the carb is always the issue, I have never had a coil fail on an onan, and if the plugs are fouled, sometimes it will run on one cylinder, but usually will still "chug". PLug wires can cause misfires and have them only fire on one cylinder too sometimes... BUT usually it is a carb issue.
 

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I dug into it tonight. I got the filter off and then got the cover off the pump. Here are some pics. I haven't been able to find a hole in the diaphragm. So I think it is good. There is one concern with the center piece to the pump. At the top there is a small chip on the carb side. I can't imagine this being the cause of my problem. What are people's thoughts?
Hey Elsimon. I'm not to familiar with Onan engines, however I have had a tractor very similar symptoms like yours has. I had a 1993 Craftsman LT4000 that was doing almost exactly what yours was doing. Dying out and not restarting and just being a problem. And sometimes, it would work perfectly fine. And when it stopped, it sounded like it had ran out of gas and wouldn't restart. I threw all kinds of new parts at it. I put on a new fuel pump, fuel filter, fuel lines, spark plug, air filter, cleaned the gas cap, cleaned the carb, and just did everything in general. However, there was one thing I didn't look into. The ignition coil. I don't know if yours has a coil, but mine did and it was $15 because it was only a Kohler Command from the 90's. It fired right up and I never had another issue with it. So I would look into ignition. What was told by my neighbor who's a retired mechanic, was that as the rubber gets old, it has trouble transferring enough energy to the plug as it heats up. Mine was so worn out that you could barely even bend the rubber. After replacing it, I had no issues at all. So I'd look into that.
 

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Discussion Starter #17
AYP123, I haven't looked into that yet. An earlier post suggested checking for spark when it does die. This would be along the same lines. I think I have the original coil and spark plug wires. I can only imagine what new parts would cost me. However not having checked yet I might be pleasantly surprised.

Saturday after getting Smurfette running I got The Ghost out and she ran fine to plow all the snow the city and county plows piled up in front. She only died a couple of times but each time started right up and ran for a while before dying again each time. I think I had her out there for only about an hour though.
 

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After our trip to Arizona we are back to the cold North. We had a couple of storms blow thru leaving about 6" on the driveway and a whole lot more from the county/city plows in front of the house. Started her up and began plowing. She died about as far from the house as she could get and still be on our property. I tried several times to get it started again with no luck. Towed her back the garage. Been a busy week at work so today was the first change I got to look into it.

It's not a fuel issue. I thought about starting a new thread but decided to continue here since this is where I started with the basic issue.

I got a spark tester from ElSimonito. Connected it up to the front plug and tried to start it. It was a little dark in the garage so it was easy to see if I had spark. Nothing. I pulled it off and tested the tester on Smurfette (SS15). Tester works. Back to The Ghost and tried the rear plug. Again no spark.

Possible causes include (that I can think of): coil, condenser and points. So the question is where do I start? Do I start with trouble shooting each item or do I buy a kit with all the parts I might need and replace them all and not worry about the next thing that might go wrong? Is there a simple fix I am overlooking? This is a Sears Suburban 18/6 with an Onan BG-MS/3272A engine.

Since there is yellow paint that matches the color of the engine I am guessing that I have the original coil and plug wires. With those being original perhaps the rest of the electrical system is also original......

I could really use some help with this.
 

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I'd try cleaning the points with a nail file and some spray cleaner,the stuff for electrical contacts works best,but carb or brake cleaner will work,just let it all evaporate completely before attempting to crank the engine over..

A quick way to test the points is to hook a test lamp to the negative side of the coil,which is grounded thru the points..ground the test lamp to a good ground and crank it over--if the points are making contact and the condensor is good the test light should flash on and off as the engine spins over..
The ignition switch needs to be on--I'd take the plug wires off so it cant start,just in case..

Points can still test "good" and not make good enough contact to make good spark so cleaning them is a must..

If you still get no spark,it might be the condensor,the best "test" is to replace one thats suspect because they can work fine one minute and kill spark the next when they short out..one that fails wont allow the coil to build up sufficient charge and discharge quick enough to make a spark jump...in a pinch just about any condensor from an old car will work..I've used many from GM straight sixes in the past..
Onan's twin tower coils seem to fail frequently,and are mega-expensive..there are ways to use a electronic ignition coil off a later GM car instead,they can be had for next to nothing at salvage yards or about $20 at parts stores new..
This video shows how to wire one up..
 

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all the parts are available from onanparts.com- you'll probably spend about $75 on points, condenser, and wires. You can get solid core wires from tractor supply or napa for a Ford 8N and use those, but the onan ones seem to be better to me. I use Champion H10C plugs, have even bought them from Walmart I think.

That could be a bad condenser- You can get a 12V condenser from Napa or a small engine shop, and try that first. Wrap your factory plug wires from tip to tail in electrical tape, and that will fix any stray sparks till you decided if you want to buy some. I doubt it's the coil, I have never had an Onan coil fail. Theyre really robust.
 
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