RPM sensor loss led to battery, contactor, and starter being replaced, when underlying issue was instead a valve that was out of it's spec'd clearance.
Three years later and this video is still getting people! Thank you, I started by replacing the battery, and still had RPM SENSE LOSS. I was able to get it running by freeing up the starter motor, it seemed to be stuck in place. If problems persist I'm going to follow all of your steps and watch the adjustment video if needed.
Brilliant video!! I have the 8kw air cooled unit and I have the same exact issues. A couple years ago I swapped in an aftermarket starter which did not solve the issue. I have confirmed my battery is good with a battery tester. I have tried to start the unit with a higher CCA rated battery from my car and same issue. I am going to check my valves and adjust them as needed. Thanks so much for making this video!!!!
Great video. I am having the same problem with my 8kw Generac. Battery tested good, also started one of my cars with it. No voltage drop through the contactor. Starter spins when off engine, but won't power through compression stroke. Pulled spark plug and no binding through several rotations. But checked valve adjustment anyway, there was just under .001 clearance, so I made the adjustment to .003. So your video was a benefit because it helped me rule out the valve clearance.
Wow. You just saved me close to $400. Thanks for taking the time to post this video and explain the issue. My generator experienced exactly the same issue - "Inspect Battery", "RPM Sense Loss", clicking. I replaced the battery and has the same symptom. Puzzled, I started researching and ran across your video. I removed the fan guard and attempted to turn the shaft (clockwise) and sure enough...parts of the cycle were restricted. The clearances were way off on 3 of the 4 valves. (I'll start checking these clearances with oil changes like I should have all along...) Also, my generator is a 17KW #5873 - so this process likely applies to a wide range.
Gracias for the video, I had a customer in my city with the same issue, I already told him to change the battery 13V for a new one (It had a voltage drop), we already changed spark plugs (They were rusty) and finally the starter would be the problem (We havent checked the contactors). best regards
Hey this is great , same model only my starter went out , gave it a heavy TAP and heard grinding before RPM sensor popped on but I will adjust Valve after your experience
One possible tip for other people with this generator or similar models, if it won’t start ,try taking the fuses out, let it sit for a minute then put them back in. I have an 8.5 kW Generac, Gen.one, been running for at least 15 years, anyway mine was having A real hard time starting and wasn’t able to start on its own, for the weekly exercise. I tried using the manual switch and it just seems like it would try to start but wouldn’t, I could tell that the battery was giving it enough juice to start and the starter was trying but it just would not kick over. After 30 minutes of screwing around with it I decided to take both fuses out and just put the continuity tester on them. After putting them back in the generator it started like a champ, so I don’t know if it’s kind of like a computer, And needed a reboot but I just wanted to put this tip on there for any other people with a similar model, if all else fails, just cut all the power to it for about 30 seconds to a minute and then put your fuses back in mine started right up and has done it several times since. Also great video there aren’t many videos out there about how to fix these models for a DIYer or average home user who can’t get service for weeks, but wants to be able to try something on our own in the meantime.
Thanks for posting this. I've had my 8KW serviced by the local Generac outfit several times because of this problem, and now it's back. Not only doesn't it crank long enough to have a chance to start, it doesn't crank at all. When I try to start it, there's a loud 'clunk' sound, which is very much like the sound a starter solenoid makes when a car battery is dead; is that the sound that yours made?
Yes. It would click or clunk and then the starter would actually make a high pitched noise from not being able to turn over. If you remove the starter, you'll get access to the flywheel. From there you can use a flathead screwdriver to turn it and if you have any portion of it being hard to turn then you may have a problem similar.
I have a Generac 8kw that looks exactly like yours. Just purchased my house a few months ago and the Generac was cycle running once per week. Now I noticed that I haven't heard it turn on at all, so I checked it out and the RPM Sensor Loss light was on. I'll have to go through the processes you explained starting with the battery and then go from there. Also, is there a need to reset anything after disconnecting the battery? I know on some Generac's, you have to go through a reset process. Another question I have is, when you turn it on manually, should the house main breaker be turned off first. This is all new to me and I was told many different things that if you start the Generac without turning off the house main breakers you can cause damage to the house, the Generac, etc. Anyone that can expand on this, as well as the RPM Sensor Loss light coming on, I would appreciate it - Thanks in advance!
There shouldn't be anything to reset. If you have an automatic transfer switch, then there is no need to do anything with the house's main breaker; power should only be fed from generac to house if the automatic transfer switch senses there has been power loss for a bit (i believe 25 seconds). If you do not have a auto transfer switch, then your breaker for the generator should be in the off position at all times and only turned on when there is no power coming from utility company, and at that point, you would switch your main breaker to off position.
Hey. Thanks so much for this video! I have the same generator with a very similar issue. Do you have any information on changing the starter? This is my next step, thanks!
Take a photo of the generator before disassembling anything, but the starter is essentially held on by a bracket and then 2 main bolts. Once the starter is off you can use a flathead screwdriver to try and turn the flywheel, which is when you'll be able to tell if there's a rough spot and determine if the valve clearance needs adjusted.
I have a propane 8kw acting up. Same problems. Just recently. The guy that was servicing it retired. He replaced the coil a couple years ago and it was good for a while but I have a question. That intake tube. Did you replace that with something aftermarket?
Would relacing a RC14YC spark plug with a RC12YC be ok? Just wondering if that would help starting and eliminate too many cranks. Need to know ASAP. Thanks
Stick with what manual calls for in my opinion. From what I understand fuel isn't provided until cranking occurs, so cranking isn't necessarily a bad thing.
@@IowanTAA Thank you for replying. Feel like I'm talking to myself sometimes on these sites. I'm kind of old school when it comes to electric starts. All my motorcycles were kickstarts which usually started first kick. My riding buddies would drive me nuts every time they would use their electric starts. . . sometimes to the point of running the battery power down. Then they would end up kick starting it and guess what? Started first kick. lol My point is, I can't stand the thought of any more than a few turns of cranking for startups. These Generacs are so touchy. Still wondering if that RC 12 might help. Guess I could try it and see what happens. . let it run for bit, pull the plug and inspect it. Thoughts?
I have a question did you know that when you're cranking that flywheel by hand that when you hit the compression stroke it will get very hard and you will not be able to do it and you may not be able to hold it on top dead center did you also know they're on the other part of the stroke cuz the Piston comes up once for the exhaust back down for the intake up for the compression then the ignition that's where you get the compression stroke that when it's on exhaust stroke the valves are very tight you shouldn't be too tight but they are tight I hope you adjusted that right and didn't teach everybody unadjust their valves I would say I don't know what to call it by the way the contactor is also known as a solenoid in the automotive world and generator world just FYI I hope you have a great day I'm glad your generator is working very well the valves were probably your problem they were probably miss adjusted they're supposed to be adjusted every so many hours great job
Generac lists the part as a contactor, and the clearance for the valve lash is quite specific. When I set mine to factory spec, I didn't notice any resistance at any point while rotating flywheel as I have explained in other comments.
Sounds like what mine is doing. Except when I got there there was more oil under the generator than normal, when I tried to start it after checking the oil, it made a grinding noise when it cranked for just a second then it never cranked again. Just a clank and no crank.
@@shanwar9844 Not 100% sure if they do (but I believe they do), but to access I believe splitting the generator would be required. To see if the compression release mechanism is frozen in the engine. remove the valve cover and spark plug and rotate the engine over slowly watching the intake and exhaust valves. Near top dead center on the compression stroke one of the valves should open up slightly to release the compression if it does not and your valve clearances are ok and lifter alignment is right, then its possible the compression release is binding.
Going through this now. The spark plug needs to be removed to rotate the engine through the full cycle. If the plug is in, it will be very difficult to rotate through the compression cycle. With the plug out, it should be easy to rotate through the complete cycle.
If it starts but doesn't run then I would say you have an air or fuel problem. Other than checking the air filter and spark plugs, if it's more involved, a professional tech is likely going to have to diagnose the issue.
Anybody can help me with this problem? Our generator wont go into Auto Mode. Every time I press the Auto button, it goes to Manual mode and start the machine. I tried to re-hard wiring method, didnt work. Thank you!
I never stated to make blind adjustments, nor did I say it should rotate freely; should be obvious to most that will be completing this repair that when an engine works to make combustion there is going to be resistance. I stated that I had issues with it rotating in a certain position, almost to the point where it wouldn't rotate at all. I then checked the lash, (valve clearance) and found It was not to spec; only then did I make an adjustment. Upon completion of the adjustment, the problem was resolved and the flywheel did rotate 360 without the level of resistance which was present before. Thanks.
@spirit seker We're on the same page; should be very little resistance except during compression stroke(s); flywheel should easily be able to rotate a full cycle. For a section in my case, it was not able to until the adjustment was made.
Thank you The valve lash adjustment did the trick. The engine now starts up right away and runs smoothly.
Three years later and this video is still getting people!
Thank you, I started by replacing the battery, and still had RPM SENSE LOSS.
I was able to get it running by freeing up the starter motor, it seemed to be stuck in place.
If problems persist I'm going to follow all of your steps and watch the adjustment video if needed.
Brilliant video!! I have the 8kw air cooled unit and I have the same exact issues. A couple years ago I swapped in an aftermarket starter which did not solve the issue. I have confirmed my battery is good with a battery tester. I have tried to start the unit with a higher CCA rated battery from my car and same issue. I am going to check my valves and adjust them as needed. Thanks so much for making this video!!!!
Great video. I am having the same problem with my 8kw Generac. Battery tested good, also started one of my cars with it. No voltage drop through the contactor. Starter spins when off engine, but won't power through compression stroke. Pulled spark plug and no binding through several rotations. But checked valve adjustment anyway, there was just under .001 clearance, so I made the adjustment to .003. So your video was a benefit because it helped me rule out the valve clearance.
Wow. You just saved me close to $400. Thanks for taking the time to post this video and explain the issue. My generator experienced exactly the same issue - "Inspect Battery", "RPM Sense Loss", clicking. I replaced the battery and has the same symptom. Puzzled, I started researching and ran across your video. I removed the fan guard and attempted to turn the shaft (clockwise) and sure enough...parts of the cycle were restricted. The clearances were way off on 3 of the 4 valves. (I'll start checking these clearances with oil changes like I should have all along...) Also, my generator is a 17KW #5873 - so this process likely applies to a wide range.
Gracias for the video, I had a customer in my city with the same issue, I already told him to change the battery 13V for a new one (It had a voltage drop), we already changed spark plugs (They were rusty) and finally the starter would be the problem (We havent checked the contactors). best regards
Hey this is great , same model only my starter went out , gave it a heavy TAP and heard grinding before RPM sensor popped on but I will adjust Valve after your experience
Thanks for your help!! Your explanation was clear and concise.
I been having sensor loss issues. Thank you very much for posting this!
One possible tip for other people with this generator or similar models, if it won’t start ,try taking the fuses out, let it sit for a minute then put them back in.
I have an 8.5 kW Generac, Gen.one, been running for at least 15 years, anyway mine was having A real hard time starting and wasn’t able to start on its own, for the weekly exercise. I tried using the manual switch and it just seems like it would try to start but wouldn’t, I could tell that the battery was giving it enough juice to start and the starter was trying but it just would not kick over. After 30 minutes of screwing around with it I decided to take both fuses out and just put the continuity tester on them. After putting them back in the generator it started like a champ, so I don’t know if it’s kind of like a computer, And needed a reboot but I just wanted to put this tip on there for any other people with a similar model, if all else fails, just cut all the power to it for about 30 seconds to a minute and then put your fuses back in mine started right up and has done it several times since. Also great video there aren’t many videos out there about how to fix these models for a DIYer or average home user who can’t get service for weeks, but wants to be able to try something on our own in the meantime.
Thanks for posting this. I've had my 8KW serviced by the local Generac outfit several times because of this problem, and now it's back. Not only doesn't it crank long enough to have a chance to start, it doesn't crank at all. When I try to start it, there's a loud 'clunk' sound, which is very much like the sound a starter solenoid makes when a car battery is dead; is that the sound that yours made?
Yes. It would click or clunk and then the starter would actually make a high pitched noise from not being able to turn over.
If you remove the starter, you'll get access to the flywheel. From there you can use a flathead screwdriver to turn it and if you have any portion of it being hard to turn then you may have a problem similar.
Thanks -- I'll give it a try.
I have a Generac 8kw that looks exactly like yours. Just purchased my house a few months ago and the Generac was cycle running once per week. Now I noticed that I haven't heard it turn on at all, so I checked it out and the RPM Sensor Loss light was on. I'll have to go through the processes you explained starting with the battery and then go from there. Also, is there a need to reset anything after disconnecting the battery? I know on some Generac's, you have to go through a reset process. Another question I have is, when you turn it on manually, should the house main breaker be turned off first. This is all new to me and I was told many different things that if you start the Generac without turning off the house main breakers you can cause damage to the house, the Generac, etc. Anyone that can expand on this, as well as the RPM Sensor Loss light coming on, I would appreciate it - Thanks in advance!
There shouldn't be anything to reset. If you have an automatic transfer switch, then there is no need to do anything with the house's main breaker; power should only be fed from generac to house if the automatic transfer switch senses there has been power loss for a bit (i believe 25 seconds). If you do not have a auto transfer switch, then your breaker for the generator should be in the off position at all times and only turned on when there is no power coming from utility company, and at that point, you would switch your main breaker to off position.
Hey. Thanks so much for this video! I have the same generator with a very similar issue.
Do you have any information on changing the starter? This is my next step, thanks!
Take a photo of the generator before disassembling anything, but the starter is essentially held on by a bracket and then 2 main bolts. Once the starter is off you can use a flathead screwdriver to try and turn the flywheel, which is when you'll be able to tell if there's a rough spot and determine if the valve clearance needs adjusted.
I have a propane 8kw acting up. Same problems. Just recently. The guy that was servicing it retired. He replaced the coil a couple years ago and it was good for a while but I have a question. That intake tube. Did you replace that with something aftermarket?
No, intake was stock.
Would relacing a RC14YC spark plug with a RC12YC be ok? Just wondering if that would help starting and eliminate too many cranks. Need to know ASAP. Thanks
Stick with what manual calls for in my opinion. From what I understand fuel isn't provided until cranking occurs, so cranking isn't necessarily a bad thing.
@@IowanTAA Thank you for replying. Feel like I'm talking to myself sometimes on these sites. I'm kind of old school when it comes to electric starts. All my motorcycles were kickstarts which usually started first kick. My riding buddies would drive me nuts every time they would use their electric starts. . . sometimes to the point of running the battery power down. Then they would end up kick starting it and guess what? Started first kick. lol My point is, I can't stand the thought of any more than a few turns of cranking for startups. These Generacs are so touchy. Still wondering if that RC 12 might help. Guess I could try it and see what happens. . let it run for bit, pull the plug and inspect it. Thoughts?
I have a question did you know that when you're cranking that flywheel by hand that when you hit the compression stroke it will get very hard and you will not be able to do it and you may not be able to hold it on top dead center did you also know they're on the other part of the stroke cuz the Piston comes up once for the exhaust back down for the intake up for the compression then the ignition that's where you get the compression stroke that when it's on exhaust stroke the valves are very tight you shouldn't be too tight but they are tight I hope you adjusted that right and didn't teach everybody unadjust their valves I would say I don't know what to call it by the way the contactor is also known as a solenoid in the automotive world and generator world just FYI I hope you have a great day I'm glad your generator is working very well the valves were probably your problem they were probably miss adjusted they're supposed to be adjusted every so many hours great job
Generac lists the part as a contactor, and the clearance for the valve lash is quite specific. When I set mine to factory spec, I didn't notice any resistance at any point while rotating flywheel as I have explained in other comments.
Sounds like what mine is doing. Except when I got there there was more oil under the generator than normal, when I tried to start it after checking the oil, it made a grinding noise when it cranked for just a second then it never cranked again. Just a clank and no crank.
Yikes, check the lash to start. Oil leak would be no fun!
@@tyleravis7362 The valve lash, going back out there tomorrow to check it all with the right tools. It only has 170 hours. We will see.
Was the difficulty turning over because of a compression release not functioning because of the valve adjustment being off?
No, lash on valve clearance had become out of spec.
@@tyleravis7362 so these gennies don't have a compression release mechanism for starting?
@@shanwar9844 Not 100% sure if they do (but I believe they do), but to access I believe splitting the generator would be required. To see if the compression release mechanism is frozen in the engine. remove the valve cover and spark plug and rotate the engine over slowly watching the intake and exhaust valves. Near top dead center on the compression stroke one of the valves should open up slightly to release the compression if it does not and your valve clearances are ok and lifter alignment is right, then its possible the compression release is binding.
Going through this now. The spark plug needs to be removed to rotate the engine through the full cycle. If the plug is in, it will be very difficult to rotate through the compression cycle. With the plug out, it should be easy to rotate through the complete cycle.
FYI model no. shown at 8:00 min mark and what he did to fix it (valve adj.) isn't shown :(
th-cam.com/video/pj596fKdIK8/w-d-xo.html
My 8000genrac starts runs for a few seconds then dies can u suggest what may be wrong
If it starts but doesn't run then I would say you have an air or fuel problem. Other than checking the air filter and spark plugs, if it's more involved, a professional tech is likely going to have to diagnose the issue.
Anybody can help me with this problem? Our generator wont go into Auto Mode. Every time I press the Auto button, it goes to Manual mode and start the machine. I tried to re-hard wiring method, didnt work. Thank you!
Ignition coil
The flywheel should not be FREE to turn 360. It called the compression stroke! If you dont know how it works good idea not to make blind adj.
I never stated to make blind adjustments, nor did I say it should rotate freely; should be obvious to most that will be completing this repair that when an engine works to make combustion there is going to be resistance. I stated that I had issues with it rotating in a certain position, almost to the point where it wouldn't rotate at all. I then checked the lash, (valve clearance) and found It was not to spec; only then did I make an adjustment. Upon completion of the adjustment, the problem was resolved and the flywheel did rotate 360 without the level of resistance which was present before. Thanks.
@spirit seker We're on the same page; should be very little resistance except during compression stroke(s); flywheel should easily be able to rotate a full cycle. For a section in my case, it was not able to until the adjustment was made.