Gas in the oil EFI

[No1Piddler]

Hi guys, I have a 2020 Cushman Hauler 1200 EFI, I did not buy it new, so all history not known. I am getting gas in my oil, driven maybe a mile a day by me and not hot rodded. Had the cart about 6 months. Not sure if it came this way or just started a couple months ago. Motor smoked when it gassed down on it, then checked the oil and was about 2 or 3 times to much oil, Changed the oil and 2 weeks later looked like maybe 1/2 quart to much. Got to thinking how that could happen, ordered a new injector and plug (plug looks good, little smoke) and installed it, about the same thing still happening. Did compression test today, 70 PSI (what should it be). Going to pull valve cover and look at rocker arms to see if might be a problem with valve opening. Can not find much info on the EFI motor to help. If something is wrong with rings or piston, does this motor have a jug or have to pull head and a pan (if it has one) to get piston out. The compression seem low but motor still runs pretty good, but unburnt gas may be blowing by the piston. Any input you might have will be a help, Thank you, Eddie
Update
Checked rockers, all seem to have full movement, intake set at .000 to .001, exhaust at .015, what is valve setting ? .000?
20210530_152903.jpg

[Fairtax4me]

You NEED to hot rod it. It’s not getting up to full operating temp, so you’re getting excess fuel dilution from the engine never getting hot.
Run it more, run it full throttle, and that problem will go away.

[Down South]

Check the gas cap. It may not be venting correctly. Try leaving it about a half turn from tight.
You changed the injector, right?

[No1Piddler]

Yes, changed injector, now I be sure to turn switch off each time I get off. So fuel pump will not run while parked. My old one, never cut switch off, but not EFI. There is no fuel return line to tank, so fuel line is under pressure for a while (till it bleeds off, somewhere) after switch turn off but tank does have a full time vent. As far as injectors go, don't think to much gas (no gas smoke), but computer or whatever may be telling it to mess up. Again don't think so, the injector only has 2 wires, but I'm guessing it is a variable voltage to control the amount of fuel, not just open or closed, but not sure on that. All kind of questions on a problem like this to think about. Not knowing much about this motor and setup. I read something, while back, where they had some kind of recall in early 2020, on some ATV with this motor for that problem. I called factory, they said the recall did not cover mine and would give no more info.

[Fairtax4me]

The EFI system on newer carts is basically the same as what has been on automobiles for the last 40 years.
The ECU controls fuel timing and duration by commanding the injector On. It's either On or Off, there is no adjustment to flow or nozzle opening. Like turning on a light switch. Fuel mixture control is changed by increasing or decreasing the On time of the injector. More On time = More fuel. Some use PWM control, but normally this is just done with duty cycle control.

The ECU commands more fuel when the engine is cold to ease with starting. Any cold gasoline powered engine has to use more fuel because gasoline doesn't atomize as well at lower temperatures. This means while it is getting more fuel tan normal, the actual burn mixture is lean, but you have that excess unburned fuel still in the combustion chamber. That unburned fuel condenses on the piston, and the cylinder walls and washes them down. Ring wash, or cylinder wash is what it's often called.

With ring wash, unburned fuel removes oil from the piston rings, and is then allowing fuel to get past the rings and into the crankcase, where it collects in the engine oil. This happens in ALL internal combustion engines, no matter what fuel they burn. The extent to which it happens varies by engine design and usage.

Why and how does engine temperature have an effect? When the engine is cold the gaps between the piston, rings, and cylinder wall are larger. This allows more cylinder pressure to get past the rings and into the crankcase. And since the ECU is commanding more fuel when the engine is cold, it also means more fuel gets into the crankcase.
When the engine gets up to operating temp those gaps close up. The piston expands and the rings expand to their normal operating size. The cylinder does as well, but not as much as the piston because the cylinder has more mass, and it has a cooling system. When those gaps close up blow-by is less of an issue, and at the same time the ECU is generally starting to see a temperature reading from whichever form of temperature sensor is used on the engine, at which point it will start to decrease the fuel rate which will then bring the fuel mixture back into the correct range for warm operation.
Not all small engines have a temp sensor. Sometimes the ECU just has to rely on programming that says run X amount more fuel for Y time period. This mostly ensures the engine doesn't stumble or pop when trying to start and accelerate. The down-side is that it means more fuel may be getting tossed into an already warm engine if it has been run for any length of time and then stopped.

The only way you can change or fix any of that is to run the engine more. It needs to reach full operating temp and stay there long enough that any unburned fuel that got past the rings will vaporize out of the oil and escape. Driving for 5 minutes and then stopping is the worst way you can treat one of these engines. Very much like the engine in your car or truck, it needs to run, it needs to get hot and stay hot. 15-20 minutes at least, longer is better.
These are glorified lawn mower engines, designed to run the most efficient at full speed. Full speed being relative here, since the designed running RPM varies based on several factors, but simply put these engines need to run at full governed throttle. That's how they are set up to be used, and where they will be the most efficient.

70psi compression sounds spot on for an engine that has an automatic compression release mechanism. That may be 100% normal. But if this engine does not have an ACR, it would be indicative that cylinder wash has ruined the piston rings, and it will never be right without a rebuild.

[CP241]

Well put. I agree with you completely. This time I won’t copy your answer for fear of retaliation and plagiarism

But

Can you tell me how many licks it takes to get to the tootsie roll center of a tootsie pop?

[ThreeCW]

Good explanation Fairtax4me

I did quick search online and found a number of cases in EFI engines large and small ... in marine, utility vehicles (quads, side by sides, golf carts, etc.) and automobile engines, where gas in oil problems have been happening (see: https://www.google.com/search?q=EFI+...client=gws-wiz)

In one posting, a suggested reason of an engine running cold is because the thermostat is stuck open.

Another post indicated that a bad pressure regulator resulted in a fuel in oil problem.

Yet another indicated a leaking injector bleeding off line pressure caused a fuel in oil problem.

Increasing your engine oil level by 1/2 quart (2 cups !!) in 2 weeks of 1 mile per day driving is a problem you will want to rectify soon.

There is probably no quick fix and it may be time to find a competent small engine mechanic who is familiar with EFI fuel system troubleshooting. I would be very concerned about potential damage done to your engine as a result of running with gas diluted oil (i.e. potential damage to bearings, cylinder wall and piston rings).

Edit: Are you seeing any codes on your EFI Malfunction Indicator Light (see attachments).

[No1Piddler]

Very good answers. Thank yall for your time and post. Keeping the temp up on the motor want work for me. I mostly use this cart to go back and forth from my house to my shop (800 ft) and around in the yard (4 or 5 ac). Most of my trips run time is around 3 to 4 min at a time, the motor never gets warm. Fairtax4me, thank you for your post, I understand everything you said. The compression is one thing I was worried about, but you think 70 is ok, that reading was taken when motor was cold. The valve setting was something still not sure of, I set the valves at .003 to .004 while I had the cover off. It seems to run ok at this setting. ThreeCW, thank you for your research, I may need to ck fuel pressure, but again, I don't know what the fuel pressure should be. The 1/2 quart to much oil is a guess, but I have seen it a good bit above full, the reason I caught the problem, is the motor started smoking when I pushed it a little hard going up a hill. I have been knocking this problem around for 2 or 3 months. But the time it started smoking, the oil had been in there about 3 months. The motor does not smoke oil or gas smoke at correct level. I changed the oil 3 weeks ago and it was just below the full line when filled, checked it last night, right on the full line now. The level increased the amount of the line in 3 weeks. I just looked at the fault light, when turn switch on, it is on (solid red), no flashes at all, with peddle pressed, red light turn off, no flash.

[CP241]

If changing your driving behavior is not an option to get the engine up to temp, I would probably consider selling this and getting an electric cart. If you live in a colder climate, lead acid batteries are probably best but if you live where it’s milder or warmer a majority of the year a lithium powered cart would be significantly less maintenance overall regarding charging nightly and etc. but either would probably suit your needs better than a gas cart

[Fairtax4me]

I think I would just find a reason to drive more.

What engine is in it? I know it's a kawasaki, but they have dozens of different variations of engines. Should have an ID label on the fan cowl with a FD-400 or FE-350 or FK-650 or some other code like that on it.
Valve clearance is usually .005 intake and 0.008 exhaust but that can vary based on the engine.