2011 honda bigred, spark, fuel, compression, won't run
Hello, first time forum user. long time reader. Thank you for all the info you have already shared online as well as thank you for any Ideas.
I flip cars, atvs bikes etc. in my spare time, so i consider myself a fair mechanic. a little above shade tree, below professional. I am building this one for my Dad Hope i am posting this in the right place Working on 2011 honda big red MUV700 that won't start. the guy i bought it from said he pulled it in the shed shut it off to unload it, and it never fired again he seemed honest I have the shop manual, and have tested several of the components and also replaced some. I am looking for ideas on what else to check. here is what i have done so far oil had fuel in it, changed. i have been pinching off the fuel line except during tests...no more fuel in the oil... i suspect a lot of cranking and no place for the fuel to go Valves were way out of adjustment, adjusted now Compression 60 PSI book calls for 80 i guess its a low compression motor. i think it should at least run poorly worst case and it sounds fine when it sputters When i release some fuel into the motor while turning it over i will get a 2-5 sputters like it wants to start sometimes if i leave the fuel on it will flood out for sure. i have Spark, it jumps about an inch, new coil(orig was bad for sure), new spark plug, peak and all voltages seem in spec. My peak tester is not what honda calls for but seems to work it is not throwing any MIL/ DTC unless i disconnect something...ie fuel injector and it will throw a code same with MAP. as well as if i unplug the temperature sensor the fan will come on so i suspect the PCM is ok. replaced the throttle body, IAC, fuel injector and MAP/TP sensors...exact same symptoms after replacement all sensors are in spec for ohms and peak voltage /ground and i checked harness continuity on some of them as well i have watched the fuel injector spit fuel, and fuel pressure at the pump is 50psi right now I suspect timing or bad computer or connection What i plan to do next in this order Check and clean all grounds, and inspect wiring for rub through and melts etc. pull the stator and crank pickup sensor...known issue on these, but within ohm volt specs. i just want to look for physical damage. pull the head and physically confirm timing. marks on cam and TDC. inspect timing chain tensioner....doing this last questions should both sides of the coil have 12 V to ground, the book is a bit vague. the book calls for min voltage on the cpk to be .7 minimum, i have 4 V any one know if these have a limit? can i adjust the cam tensioner without the special tool and before i take off the head? the valve movement seemed like it could be just a hair late on starting up or down at the end of a cycle...could just be in my head. one weird peice...i have an inline spark testing light...while cranking it over if i give it full throttle the spark goes away....maybe this is a clue anyway as you can see i am looking for some pretty advanced help, which i have found on other parts of the forum so i have high hopes. if you live in colorado come by with the honda scanner and ill buy your a beer. Thanks either way and if i get it on my own i will let you know the results too. Thanks happy riding...ktm 350 bike is my weekend machine btw... i have probably passed some of you. haha |
Honda Big Red
Originally Posted by micademas
(Post 3402937)
Hello, first time forum user. long time reader. Thank you for all the info you have already shared online as well as thank you for any Ideas.
I flip cars, atvs bikes etc. in my spare time, so i consider myself a fair mechanic. a little above shade tree, below professional. I am building this one for my Dad Hope i am posting this in the right place Working on 2011 honda big red MUV700 that won't start. the guy i bought it from said he pulled it in the shed shut it off to unload it, and it never fired again he seemed honest I have the shop manual, and have tested several of the components and also replaced some. I am looking for ideas on what else to check. here is what i have done so far oil had fuel in it, changed. i have been pinching off the fuel line except during tests...no more fuel in the oil... i suspect a lot of cranking and no place for the fuel to go Valves were way out of adjustment, adjusted now Compression 60 PSI book calls for 80 i guess its a low compression motor. i think it should at least run poorly worst case and it sounds fine when it sputters When i release some fuel into the motor while turning it over i will get a 2-5 sputters like it wants to start sometimes if i leave the fuel on it will flood out for sure. i have Spark, it jumps about an inch, new coil(orig was bad for sure), new spark plug, peak and all voltages seem in spec. My peak tester is not what honda calls for but seems to work it is not throwing any MIL/ DTC unless i disconnect something...ie fuel injector and it will throw a code same with MAP. as well as if i unplug the temperature sensor the fan will come on so i suspect the PCM is ok. replaced the throttle body, IAC, fuel injector and MAP/TP sensors...exact same symptoms after replacement all sensors are in spec for ohms and peak voltage /ground and i checked harness continuity on some of them as well i have watched the fuel injector spit fuel, and fuel pressure at the pump is 50psi right now I suspect timing or bad computer or connection What i plan to do next in this order Check and clean all grounds, and inspect wiring for rub through and melts etc. pull the stator and crank pickup sensor...known issue on these, but within ohm volt specs. i just want to look for physical damage. pull the head and physically confirm timing. marks on cam and TDC. inspect timing chain tensioner....doing this last questions should both sides of the coil have 12 V to ground, the book is a bit vague. the book calls for min voltage on the cpk to be .7 minimum, i have 4 V any one know if these have a limit? can i adjust the cam tensioner without the special tool and before i take off the head? the valve movement seemed like it could be just a hair late on starting up or down at the end of a cycle...could just be in my head. one weird peice...i have an inline spark testing light...while cranking it over if i give it full throttle the spark goes away....maybe this is a clue anyway as you can see i am looking for some pretty advanced help, which i have found on other parts of the forum so i have high hopes. if you live in colorado come by with the honda scanner and ill buy your a beer. Thanks either way and if i get it on my own i will let you know the results too. Thanks happy riding...ktm 350 bike is my weekend machine btw... i have probably passed some of you. haha Have you had any luck finding the problem? From what you described mine is doing exactly the same thing. |
honda big red
the timing chain had jumped, in my case i just retimed it, and used it around my property. Sold it a while back was still going.
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Thanks for sharing this info. This happened on mine about two years ago and I replaced timing chain, tensioner, oil, ect. Thought it was possible but was thinking electrical because of no spark at full throttle.
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Triple check your timing, and physical tdc with stick in spark plug hole.
May have timed 180 out. I have had at least 3 atv's with no spark on upper end throttle. it is always a weak stator, or stator with tiny ohms to ground almost undetectable or when hot. there are good you tubes on stator live and bench check. |
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