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Onan MDL4 Fuel Issue


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  #1  
Old 09-04-2017, 09:54:48 AM
ageless1 ageless1 is offline
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Default Onan MDL4 Fuel Issue

I have a 20kw marine generator that is spilling fuel into the exhaust. When I shut the fuel valve off the sheen out the exhaust stops. I don't have access to my manual until I get back to the boat and twinscan is down so I though I'd pick the experts brains
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Old 09-04-2017, 10:27:00 AM
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Billy J Shafer Billy J Shafer is offline
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Default Re: Onan MDL4 fuel issue

If the oil level is normal. The only other way is a bad injector leaking fuel into the cylinder.
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Old 09-04-2017, 10:32:59 AM
Birken Vogt Birken Vogt is offline
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Default Re: Onan MDL4 fuel issue

What do you mean when you shut the fuel valve off the sheen stops? Doesn't the engine stop running when you do this?
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Old 09-04-2017, 10:47:55 AM
nothingbutdarts nothingbutdarts is offline
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Default Re: Onan MDL4 fuel issue

Not loading it down enough and wet stacking? Thermostat stuck open and not running warm enough?

As mentioned above, without a little more detail of what is going on it's hard to say what is being asked.
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Old 09-04-2017, 10:48:25 AM
AngrySailor AngrySailor is offline
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Default Re: Onan MDL4 fuel issue

Does it have a fuel cooler? If the cooler sea water is piped to a wet exhaust could explain your issue
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Old 02-12-2018, 01:28:32 PM
ageless1 ageless1 is offline
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Default Re: Onan MDL4 fuel issue

Sorry I haven't followed up on this, discovered the sheen issue was not from the generator, but I do have a new issue.

Model number: 20MDL4-3CR/25804B
Serial number is D870891256

I noticed my fuel filter was leaking (while running)when in the process of changing. Once I installed the new filter I continued to get a leak from the back side of the filter. I removed the two nipples that the filter slides on to ensure they weren't damaged, and I see nothing abnormal. I installed them back, checked the filter inserts to ensure no damage and placed the filter back on---still leaks.
My manual doesn't reflect the removable nipples so I am not sure of the answer to this but are those nipples supposed to have o-rings on the end that pushes into the mounting plate?
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Old 02-12-2018, 01:33:21 PM
ageless1 ageless1 is offline
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Default Re: Onan MDL4 fuel issue

here is the filter
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Old 02-12-2018, 01:33:49 PM
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Default Re: Onan MDL4 fuel issue

A few pics would be good , your model is not common enough that many guys would have direct experience with it but a number of the Stakkers have many years of general experience. Cheers Dan
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Old 02-12-2018, 01:37:33 PM
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Default Re: Onan MDL4 fuel issue

here is one of the nipples
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Old 02-12-2018, 01:56:34 PM
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Default Re: Onan MDL4 fuel issue

There should be two o-rings on the filter. That seal off the system. I have never seen the nipple come off. Clean it off well and see where the fuel is coming from.
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