https://www.manualslib.com/manual/11...0.html?page=11 Your atv chart is listed in left lower side of page

 

thanks, I bookmarked it.

crazy it starts cold with 35 psi.

 

There is a one way check valve on your compression tester. Your engine isn't holding pressure in the head and cylinder.

There is a leakdown tester you can buy to use compressed air to determine how fast it's leaking down. All engines will leak down. The issue is how fast.

An engine running rich will put dry black carbon deposits on the plug. But, for example, if you have a carb engine, you choke it to richen the mixture to start it cold. Usually you run it for a bit to warm it up and then take the choke off. If you choke it, start it, run it for a few mins with the choke on, then shut it off and remove the plug, even if the engine is running properly you'll see a slightly darker plug. Then, if you reinstall the plug, run it like normal with the choke off, then shut it down and remove the plug, the black carbon deposits will burn off and then will be white or off white. A spark plug that stays black no matter what is indicative of excess fuel. Thick, gunky, oily black deposits are indicative of oil being burnt.

You mentioned you saw a fuel mixture coming out when you cranked it over with the plug removed. That hints to me your injector is feeding too much fuel. The amount of fuel per power stroke is miniscule.

 

I know there are leakdown testers, but just from what I saw I don't think mine leaks very fast which would be good I'm assuming.

I'll try to rememeber to take a picture of the plug. I recall it being very black and thick, but not wet or oily.

I'll also try to take a video of the fuel coming out of the cylinder. Keep in mind when it was shooting out, I was holding the throttle wide open. Would the EFI not accomadate the wide open throttle by matching it with more fuel? Or is there a sensor which tells the injector to add more fuel?

 

With the check valve in your compression tester, leaking down or not leaking down is irrelevant. When you crank the engine over, it forces pressure into the tester which then doesn't allow it to flow back into the cylinder due to the one way check valve.

A slow cranking engine (but otherwise functioning correctly) will test low on compression but if it can start, it will run fine.

The amount of fuel in the cylinder per power stroke is almost non existent. Very very tiny amount of fuel and should be extremely finely atomized....basically just vapor. If you are seeing liquid drops, even small ones, you have too much fuel entering the cylinder. The big, massive clue is the dry, black carbon deposits on the plug. Low compression won't cause that. Excess fuel will. Everything you keep describing is excess fuel. It sounds like you maintain your equipment very well so for that mileage, unless you have a broken ring, it's highly doubtful that your rings are shot. Most early wear on engine rings comes from poor maintenance....too few oil changes and air filters leaking dirt in. Doubt that's something that effects your equipment. If you had a broken ring I would also expect to see scored cylinder walls...which would trigger burning oil. But, you aren't describing that either. Fuel in the crankcase doesn't come from low compression.

You may have a couple issues. A weak starter or battery could cause the slow cranking. A leaking injector would cause the excess carbon and hard starting. Combined together they would DEFINITELY create hard starting symptoms.

The PCM takes inputs from the sensors and decides, based on the info from the sensors and the preprogrammed data in the PCM, how much to open the fuel injector. The pressure from the fuel pump is what actually feeds the fuel into the intake. The injector is just simply a variable valve that is supposed to only open the amount it gets told to by the PCM. If it begins leaking, it will be feeding more fuel than the PCM is directing it to.

Another thing is....If the injector is leaking fuel into the intake when it is shut off, the fuel is washing the oil from the cylinder walls as it runs down into the crankcase. That increases wear (due to lack of oil at start up) and decreases compression...again due to lack of oil helping the seal. There is very very little oil on the cylinder walls in a properly functioning engine anyway so washing off the oil on the cylinder walls is a bad thing.

 

Any updates on this atv?

 

I'm sorry for not updating this thread any sooner, but I just got the ATV fixed tonight.

I have a small garage and so its impossible to repair more than one machine at a time. After I last posted on this thread my truck broke down 3 times, wife's car broke down 2 times, and a snowmobile needed work. So the acrtic cat just kept being put on the back burner.



Anyways, after a LOT of thought I figured what is probably wrong with the machine is the starter. I mentioned ealrier that it was turning very slowly and took a LOT of cranking to fire up. While starting it, the lights on the ATV would also dim down. I also mentioned this machine eats batteries for lunch and when it was newer the factory battery lasted about 4 years.

So I figured during this slow cranking starting I was pulling current from the spark plug as well. This would also make it more difficult to start. So while it slowly cranked over and over, the fuel injector was spraying into the cylinder and the plug had very little spark. This is what keeps fouling the plug so bad and so fast. When the plug got really fouled, then it caused my other issues of stalling, rough ilding etc..

A bad starter also accounts for loss of compression. The start was REALLY slow and sturggling to crank the engine over and over and over before it fired. There's no way I could properly test compression with my old starter.

All this also explains why it eats batteries.

And it explains the fuel in my oil. Over time, the injector sprayed so much while it struggling to crank and fire, the extra gas would drip into the crank case.

Anyways, put a new starter in tongiht and holy mother of god it starts better, faster and easier then my brand new honda rubicon. I can't even count how fast it cranks per min becuase it cranks so fast and fires up after one or two cranks.

I'm an idiot and forgot to test the compression with the new starter before putting it back togehter. I'd test compression now, but the front rack and plastics need to come off to fit the tester in there. I'll ride it and enjoy it rather than pull it all apart. If the problems continue, I'll test the compression again.

I think right now, I need to really work on getting all the carbon build up out of the engine. WIth the plug fouling up so bad, I'm guessing theres tons of carbon in the engine as well. I put a 1/4 can of seafoam in fresh fuel tongiht and I'll burn at least 1/2 tank of gas this wekeend and run it hard.


Thanks for the help and fingers crossed I have solved this problem.

 

Glad your making headsway on this atv also thanks for updates glad starter help issues like we mention in 6 page post please keep us ALL update on any changes and I know your glad you can ride some now an not burn quad..lol Good Luck Our friend

 

I had lots of free time tongiht so I tested the compression with the new starter. on a warm engine at WOT the PSI is about 110-115. My compression testor is a cheap chinese amazon special, so I wouldn't doubt its higher than the reading.

After I compression tested it I sprayed a full can of seafoam top end cleaner, then let it sit and ran the **** out of it. Very noticeable difference after the sea foam.

 

Awesome Thanks enjoy it