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Discussion Starter #1
I know this is a honda forum but I can’t find ANYTHING online about this atv not even a picture NOTHING!! Ok well my friend has a Craftsman 300 atv (I donno if they are pos good or what ) It's a a/t 2 and 4 wheel drive (you can pick with the flip of a switch) I also think it’s fuel injected from what he was saying. Now it has been acting really funny and they took it to a shop and they can’t figure out wtf deal is with this machine. It only starts if you have you gas all the way down when you start it you can let off when it starts and it will idle fine. MOST of the time when you give it gas it just dies or just about dies. You have to pump the gas to get it to rev up more (and sometimes it works sometimes it just dies) the atv will run fine at 100% throttle for awhile. Sometimes it will bog down and the rpms drop like a rock out of the sky. (it has a digital read out of rpm/mph/temp ect.) Now he told me he has been putting 87octane in that atv. Well it clearly states on the gas cap 90 octane or better. So I put a whole can of sea foam in the tank we ran the piss out of it and it seemed to work ALITTLE better but still giving us the same prob. So my next step was siferning all the old gas out. Put 93octane and ran the piss out of it seemed to run little better but still same prob. I mean the atv is rid able but when you stop and try to go again it starts being dumb. Now I did look at the air filter it's clean but I did notice a SMALL amount of gas right where the filter meets the pipe but not much. Now the only thing I can think of at this point in time is if they were running 87 octane for the last year or so maybe the exhaust has gotten clogged up for all the carbon build up from the engine not burning the 87octane gas efficiently. My friend says that this atv can run 45mph top speed but yesterday I at first I couldn’t get it to run anything faster than 25mph and that was with 2wd not the 4wd if I put it in 4wd then it goes even slower cus of the more stress being put on the engine. But after the sea foam and the new gas it will get up and run close to 35mph now. If you hold steady at 6,000rpms (28-30mph) it will run fine with no prob. but as soon as you push the gas down any further it starts acting like a drunken monkey again. I’m kinda stumped on wtf is going on with this machine. I know a good bit how to troubleshoot most stuff with engines but this thing is pissing me off. Any help guys? I know this isn’t a honda atv but I’m not going to try and find another forum just to ask this question. Hell I can’t even find ANY info on this atv period Iv google the crap out of it Iv been on craftsman’s web site...all dead ends and I know the atv isn’t but maybe 2-3 years old it's fairly new. Well thanx for reading my looooooog @ss post. Thanx in advance!!
 

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Discussion Starter #2
Something just popped in my head...I never looked at the spark plug at all. But I’m sure when they took it to the shop that was one of the 1st things they checked...well I hope so. I will check the spark plug 2day and see how she looks. I don't think they told the shop they took it to that they were running lower octane than the machine needs b/c he didn't even know he had to put 90octane or higher in the damn thing. But I guess the cool thing is his g-dad told him if he could blow up the atv he could get a new one…lol
 

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Well let's think about this for a min.... if you were working on a fuel injected car and it was giving you the same symptoms what would be the first thing you'd look for???? I personally would start with the fuel filter. Replace that, If you are still having issues where would you go next? I would remove the intake hose and look in the carb throat and see how much sludge build-up there is if it fuel inj. I would clean the TPS and IAC if they have those then run a fuel pressure check below spec I would be looking at a fuel pressure reulator then on to the fuel pump. Questions for self: Is it an intank fuel pump? Of so does it ave a strainer on the pump intake side like 90% of electric pump have? If it's an external pump is there a strainer in the tank? I'm not to sure how the injector is placed in a quad's carb but if you are able to get to it to see it while the engine is running you may be able to see how the injector is firing?? But you will need a timing light to see it fire. You would be looking for a very even cone mist and deviation in the spray pattern could be Pump, regulator or Possibly even an injector... There that's my two cents. maybe some of my Jibberish will be able to assist you. good luck bro.
oh by the way if you find that the fuel pressure specs is say between 4 and 9 psi go grab yourself a universal electric pump from NAPA only if you are able to install it in line without cutting anything. and then try to run it if it's running good then you will know what the issue is.
 

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Hea can run low octane if he wants too just add a can of octane booster no biggie or spen the extra 10 cents and get mid grade. I never run 87 in my quad 104 for me.
 

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Discussion Starter #6
Yeah I’m trying to do everything I can w/o pulling out the tools. B/c it's not my atv I don’t wanna mess. Something that isn’t mine. If it's mine and I break something then I’m like "ohh well just buy another one" But someone else stuff its a little diff. But I’m about to head over next door and play with it a little more and I will get back with ya on any progress.
 

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Discussion Starter #7 (Edited)
Well I played with the atv some more yesterday and this is what Iv come down 2 this so far...Well this pos craftsman is a fuel injected engine. Now since I have put the 93 octane gas it has been running RICH really RICH. When you finally get the damn thing started you can see a mist of raw fuel on start up that comes out of the muffler and after it starts to idles you can stained behind the bike and the exhaust reeks like raw fuel. Some at this point I know the engine isn’t burning all the fuel that is being dumped into the combustion chamber. So I pulled the spark plug it was 50/50 it looked ok but it could be replaced. So I cleaned it with some carb cleaner and stuck it back in and it didn’t make any diff. So I’m having my friend pick up a new spark plug when he gets off work 2day and see if that will help. But I don’t think it's gonna do a damn thing IMO....but it's worth a try. Now since I know some what about PGFI I’m THINKING maybe the injector is bad and stuck open. But when it comes to electronics it can be just about anything ya know? SO from the new info I have provided can anyone help me out?? I’m just a little stumped at this point.
 

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Discussion Starter #8
Well I think narrowed it down to the injector stuck open or the timing and or the a/f ratio is off. I popped off the exhaust from the engine and started it up. It shoots 6in flames out of the motor.
 

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Discussion Starter #11
It says “craftsman 300” on the side of the bike but that’s it nothing else. So it's made by sears...I have searched the web for over an hr I can't find ANYTHING about this bike. From what my friend was saying they bought it in 03-04 so it's not all the old. I might get sears on the phone and see if they can’t help me…but I doubt it.
 

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FYI: 87 octane fuel burns easier and more efficiently than 90+ octane. All a higher octane rating will get you is an increased combustion temp and higher resistance to detonation (pinging). High octane fuel is generally recommended for high compression engines because the more you compress fuel, the more likely it is to detonate. To get the most efficiency out of an engine, run the lowest octane rating you can without pinging.

flcb7, the manufacturer recommends 90...my experience has always been that manufacturers tend to play it safe and overrate the requirements. However, using 93 octane fuel will actually make the fuel harder to burn, the engine less efficent, and is a waste of money. If the engine is not pinging, 87 octane is just fine...and much more efficent.

In regards to the original problem, since this is a fuel injected engine, have you looked at sensor failure (TPS, MAP, O2, etc)? Also, fuel pressure on FI engines is relatively high compared to carbed engines...what's the measured fuel pressure at the injector?
 

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Discussion Starter #13
Well I think I found out most of the prob. IT'S CHINEESE MADE! Duh no wonder it's a POS! I have one more thing I’m gonna try be4 I start breaking out the tools and f-in up some one else’s bike. I’m gonna try and reset the ecu and see if the a/f ratio can be reset...it's worth a try since it’s free. But IMPO I think the injector is bad. I’m trying to talk him into selling that POS and getting another honda 300.

I haven’t done any type of fuel press. Test yet cus I just don’t have the tools right now. But if I can get my hands on a psi gauge and some scraps I can make a homemade engine compression test. The prob. is I don’t know what type of compression this engine is suposta make. S**t I might be way off and the engine might just be totally f**ked. Cus if the engine will only run @ 100% throttle then maybe the extra gas is making the engine hold compression to start up and only run @ full throttle...kinda like putting oil in the combustion chamber when you know the cyl walls are worn out.

AHHHHHHHHHHHHHHHHHHHHHHHHHHHhhh....you got to love engines!
 
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