Onan Emerald I genset, hard to start and can?t keep running.

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Jasindude1

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Mar 20, 2018
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So working on the generator of my 88 Pacearrow, changed the plugs, installed new starter, primed the fuel pump (I am using a 5 gallon container) anyways I can get it to start and run for a few minutes and then it dies, after it dies it will just crank and crank and will not start again, if I let it sit (I let it sit overnight) it will start again and run for a few mins and do the same thing. I can?t keep it running at all, today the smoke was grey color, yesterday it was kinda dark n black. I don?t wanna pay out $$$ to the dealer, I was hoping someone on here can help me out, I need to do this on a budget. Please help. Thank u
 
check/clean air filter element. Also the float bowl on carb...There probably is a lot of gunk inside needs to be cleaned out. Do you have a new gasoline filter installed? Definitely sounds like fuel problem...
 
Those old Onans used points and condenser ignition didn't they? Coil could be bad also.
 
The air filter is good, the fuel pump is the faucet style, it?s clicking so I?m thinking that?s good. It almost seems like when it runs for a few mins that?s it flooding the engine. Idk sure seems to be a pain, I have the carb soaking in Seafoam currently. Ugh. So frustrating!
 
If the coil or condenser is bad, it may sometimes start and run fine, but stall and not start again until it cools off.
 
Well I just got it started it ran great for about 5 minutes, white smoke coming out pretty steady. But I am noticing fuel in the oil, what would cause this?
 
It is flooding probably due to a worn or gummed up carburetor inlet needle. Gas is pouring into the carb throat and entering the crank case. Did you completely diassemble it or just soak it as an assembly?
 
So.... I took the carb off, I inspected the floats it actually looks pretty good. I cleaned a little bit and atjusted, I don?t know if they were sticking or not anyways the other thing I noticed was the gasket before and after the carb we?re missing, hey weren?t even there. Idk if that would cause this issue or not. I cleaned the carb, which wasn?t even dirty, idk if the floats were the issue I put them in water and no holes were found. What else could this be? I completely dissesmbles the carb and cleaned it but honestly nothing was really dirty or gummed up.
 
I've never heard of a "faucet type" fuel pump. But if it a mechanical pump attached to the engine block, that is the likely culprit.  It will have a diaphragm in it that probably has a hole in in. This would allow fuel into the oil and oil into the fuel.
 
The older horizontally opposed Onans also have a crankcase breather that can fail, causing the engine to smoke and will pump oil straight into the carburetor.
 
this is the style pump I have, https://www.pegasusautoracing.com/images/L/1107.JPG

so the pump will allow fuel into the oil?
 
I think you have a couple problems. First, I think your fuel pump is dead. Secondly, like Roy M said, you have a worn or stuck needle valve causing fuel to enter the crankcase when the engine isn't running.

I recently had a fight with the carb on my generator. After keeping my head in the clouds for too long and not running the generator on a regular basis, the carburetor went wonky on me.  I ended up using a temporary fuel line ran from the pump to a gas can filled with non-ethanol gas and sea foam. After two gallons of this mixture, the engine was starting to run slightly better. I ended up removing and cleaning the carburetor twice before it would finally run correctly.
 
Why would you think my fuel pump is dead? I might just buy the whole rebuild kit for the carb then bc I couldn?t tell just by looking at the float needle if it was worn or not, it looked fairly new and so did the floats
 
Jasindude1 said:
this is the style pump I have, https://www.pegasusautoracing.com/images/L/1107.JPG

so the pump will allow fuel into the oil?
Click to expand...
That's an electric pump. It should be okay and not cross contaminate oil/gas.
 
Jasindude1 said:
Why would you think my fuel pump is dead? I might just buy the whole rebuild kit for the carb then bc I couldn?t tell just by looking at the float needle if it was worn or not, it looked fairly new and so did the floats
Click to expand...

Because I had a riding mower that did the same thing. It would start easily when cold then sputter and die once it warmed up. Once it was warm, it wouldn't start or run without the choke out. I installed a new fuel pump and it ran like a champ.
 
The missing gasket.. While the choke is cold it may allow enough fuel into the engine to start and run but as it opens the missing gaskets can let too much air in causing a stall.  That would be one suspect.

But you also had gasoline in the oil
This could be caused by dirty needle valves (The float valve) Float looks good but valve does not close, this will cause flooding and excess fuel can get past the rings.

Had that happen on a VAN once. And the cause, as it turns out, was a failing fuel pump. Never did figure it out but the pump failed 100%, leaving van dead in road. Slapped a new fuel pump on and solved BOTH problems.

I learned a lot with that big Dodge Van. (The hard way)

There are other possible causes as well.. But it's been a long time since I worked as a mechanic.
 
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