D 160 (16 onan) choking out after 45 min.of use???

[1maidenfan 201]

OK guys, I actually had to mow my yard last week and today. Last week when I was mowing after about 45 min. the engine started acting like it was starving for fuel or the choke was on. It actually died on me I figured that since it had been so long since i had mowed that the carb got gummed up, so I cleaned the carb completely and changed the fuel filter hoping that would do the trick. Well had to mow again today and like last week about 45 min. into mowing and the engine starts missing out and wanting to die. If I turn it off and let it sit for about 30 sec's or so it fires right back up and runs for a few then does the same thing over and over

So I'm thinking fuel pump

I'm also thinking coil

I checked over the wiring thinking maybe a loose wire or a wire shorting out, nothing

Normal running condition the engine does not smoke at all, now when it starts running rough I'm seeing light smoke from both exhaust. Once it starts running better the smoke goes away That almost makes me think I have valve troubles

ANY HELP WOULD BE GREAT :text-thankyoublue:

[coldone 35]

Check the fuel cap vent. If it gets clogged it creats a vacuum in the tank and dosent let the fuel be pumped.

[Jake Kuhn 1,547]

Mine used to do that when you put a load on it,but if you shut the deck off it would gain all its power back,reset the points and it ran fine ever since. Jake

[JackC 616]

If it runs OK for 45 minutes I would think the valves are OK.

Sounds like a carburetor or fuel delivery problem but could be electrical.

When I cleaned my D-160 ONAN carburetor I soaked it overnight and replaced the float valve and seat and followed the service manual for the initial settings for the needles. I also use clear fuel line just before and after the fuel pump so I can see if there is a fuel delivery problem.

If the fuel drains back over time after the engine is shut off the pump may be weak.

The reed valves in the pump loosen up over time.

I have had problems with a loose vacuum line between the crankcase and the pump.

The clamps on each end of that vacuum line need to be secure.

I use long nose pliers to get behind the tin to secure the clamps.

Here is a picture of the clear fuel line that helps diagnose fuel delivery issues.

[JamesBe1 80]

Wish I knew enough about onan's to offer an opinion. I would love to know the fix when you find out.

[zeedubbya 18]

My 520h was doing the same thing--would run for about 20 min and then choke out. I researched on here and learned of the lovely Onan valve issues so I removed the air cleaner and it was spraying fuel up through the top of carb and eventually the fuel "backwash" would kill it and it would smoke a bit too. I could operate it without the air cleaner and it wouldn't die but it sprayed fuel everywhere. I went ahead and adjusted the valves per a recommendation on here, and it runs great now--no fuel spray. I know your issue could be many things but try pulling the air cleaner off it and see if you have fuel spraying up through the carb. If it is I think you need to adjust the valves--it's a pretty quick process even if you aren't great with a wrench. I'm not and it only took about an hour. Let us know how it goes!

[1maidenfan 201]

Thanks all for the support

I'm not really seeing any fuel spray out of the carb. I adjusted the valves at the begining of the season when I rebuilt the carb. Mine was actully spraying fuel before I done the valve job(took valves out and refaced/seated them) I tried running it with out the air cleaner for awhile(which is a BIG no no!) and it still did it.

I am thinking more and more it is a fuel delivery problem, will check old posts on here as to which electric fuel pump will work with my engine. I know I have seen pposts on here about this.

I like the idea of the CLEAR fuel line , will be looking for some of that also.

Again, thanks for the support.

GOTTA LUV THIS SITE!!! :happy-jumpeveryone:

[1maidenfan 201]

Ok guys after some serious thought and curiosity I figured out what was wrong with my tractor.

Here goes...watched a short video that was posted on redsquare that showed how to reseat the reeds in your fuel pump. As I started taking fuel lines off, I noticed some thing that looked like sand rewind to last week when first noticed problem, when I went to change the fuel filter I thought I seen some sand or some thing that came out of the fuel line well at that time just thought it was some thing already on the shop floor.

Ok, now today as I go to take the fuel lines off so I can check the fuel pump, there is that sand looking stuff Ok whats going on is what Im thinking Look at the fuel filter and its full of white sand looking stuff. Pulled the fuel line off at the tank and blew it out, all kinds of sand came out Time to pull tank and check. Dont have any idea as to how in the world sand got in my fuel tank but their it was Actually looks like sand blasting media.

Cleaned every thing , replaced all fuel lines and fuel filter and the ol onan is running and running good.

Sand in the tank, who'd a thunked :confusion-shrug:

[JackC 616]

Could be the ethanol in the fuel doing strange things to the tank and fuel system that previously used pure gas.

When I cleaned the carburetor on my 520HC I found about a tablespoon full of stuff like you described.

Here is some reading on the things ethanol can do for an old wheel horse tractor that was built to run on pure gas.

Pure gas does leave varnish deposits over time and apparently the ethanol cleans if off the inside of the fuel tank and lines.

I just switched to pure gas ( I can by it in NY state) and started using Star tron based on the recommendations by an outdoor equipment and small engine shop.

http://mystarbrite.com/startron//content/view/14/37/lang,en/