Forum Discussion

gsf35099's avatar
gsf35099
Explorer
Aug 14, 2016

Generac gene 7.5KW shutting down

Hello gang,

Got an issue with my generac gene and looking for some thoughts and confirmation of my troubleshooting.

The gene starts and runs great when I start it up after sitting. After ~ 1 1/2 hours to 2 hours it will shutdown like a kill switch has been pressed. The gene has 2333 hours and I have always maintained it as required every 250 hrs with oil, oil filter, air filter & fuel filters.

There are 3 kill switched
1. Oil pressure
2. Temperature over temp switch in captive coolant - the water pump housing from what it looks like. Not a easy dude to get to.
3. Over speed shutdown - A DC control circuit board sensing speed frequency from alternator AC output - if exceeds ~72 Hertz will cause an auto engine shutdown.

1. Oil pressure - (seems to not be the problem as I monitored the OHMs - normally open when running & meter showed open until the engine stopped) I was staring at the meeting when the engine stopped so I'm confident this one is not it.
2. Testing now again letting gene run to see if the shutdown will occur (have AC output breaker on gene off. Have not tried this method as I've had the AC's running when the gene dies, so not sure it an overtemp or #3, so this test should let me know) This is a normally open switch and will close at ~240F or greater. The cooling system is full with good coolant and if it stops I'm not sure how to test the actual coolant temp..... ANY IDEAS? The manual says these switches can go bad, but if it really over-temping then it may need to be flushed.
If it continues to run for more than 2 hours, then I'm going to turn on the power and kick the AC's on and see what happens. This should tell me if it dies that #3 might be the problem.

I was hoping this was one of those problems I could fix, but this one is kicking my tail some and not cooperating with me. Haha. I have fixed way more complex items on the RV than this. Would prefer not to have to take the RV to a gene dealer, but it may come to that if I can't find the root cause.

Sorry for the lengthy message and appreciate any thoughts. I notice there are not many Generac Gene's on RV from what I have searched.

Thanks,
Kaven
Class A
  • gsf35099's avatar
    gsf35099
    Explorer
    Aug 21, 2016
    bounder39zman wrote:
    Overspeed shutdown point is adjustable with small "pot" on control board
    but probably not your problem. If this is out of adjustment, usually will shut down on start up, whether loaded-unloaded, hot or cold. Make sure fan/water pump belt tensioner and pulley are maintaining belt tension. Your symptions sound like temp issue. Generac had problems with temp senders, and offered upgrade part years ago...but since they abandoned mobile gen market, dont know if still available or not.
    btw, a/c. voltage is also adjustable by "pot" on regulator, but 115vac with a.c. units running is perfectly ok...
    make sure you check coolant level at filler pressure cap (when cool!)
    not just looking at overflow tank. good luck


    Thanks for the info. I've pulled the panels off & watched the belts & tension and both belts were changed ~3 years ago along with the tensioner. I too thought it was a temp problem and have checked the coolant at the radiator fill not the overflow.
    I've got the new voltage regulator & plan to install it tomorrow. Hoping that fixes the problem. If not, then I will dive into the temp more, but struggling with that since it will fire up within minutes of shutting down and run.
    I've Had it over temp before and it would die every time after it got warm within a few minutes.
  • hanko's avatar
    hanko
    Explorer
    Aug 20, 2016
    I knwo this doesnt have anything to do with your issue, but I think 250 hrs between oil changes is way to long, just saying
  • bounder39zman's avatar
    bounder39zman
    Explorer II
    Aug 20, 2016
    Overspeed shutdown point is adjustable with small "pot" on control board
    but probably not your problem. If this is out of adjustment, usually will shut down on start up, whether loaded-unloaded, hot or cold. Make sure fan/water pump belt tensioner and pulley are maintaining belt tension. Your symptions sound like temp issue. Generac had problems with temp senders, and offered upgrade part years ago...but since they abandoned mobile gen market, dont know if still available or not.
    btw, a/c. voltage is also adjustable by "pot" on regulator, but 115vac with a.c. units running is perfectly ok...
    make sure you check coolant level at filler pressure cap (when cool!)
    not just looking at overflow tank. good luck
  • gsf35099's avatar
    gsf35099
    Explorer
    Aug 14, 2016
    Here's the latest update of troubleshooting and a little more:

    Ran 2 1/2 hours with minimal load (no AC's)
    Fired up AC's and died within 3 min's
    Took 3 attempts to start (first 2 died within 10 sec)
    No AC's and ran for 30 min
    Fired up AC's and died within 3 min's
    (noticed volts at outlet in kitchen dropped from 120 to 115

    Cleaned radiator fins and some of generator with water (low pressure power sprayer)
    Let RV set for ~3 hours
    Fired up gene and AC's immediately
    Ran for 17 min's and died
    Watched volts at outlet go from 122 down to 115.5v over the 17 min's and gene died at 115.5v
    Took 3 attempts to start (first 2 died within 10 sec)
    No AC's and generator is still running 20 min & counting. Volts at 121.9-122v.

    Walked over and talked to DW while she was coloring and said "I'm really thinking it the voltage regulator". DW then says, "well that is what it was when we had it fixed by that kid about 5 years ago, remember? It kept dying on us."

    Guess my older mind is just not handling the pressure like it used too. Ha.

    Oh, well. Got a new voltage regulator on order and will see how things go next weekend.

    Thanks again to those that chimed in. I will let you know what I find next weekend.
  • gsf35099's avatar
    gsf35099
    Explorer
    Aug 14, 2016
    Don't think its a fuel problem. The unit stops within minutes of the AC's being turned on after the generator has run fine for 2 1/2 hrs and then again after 30 mins.
    I'm thinking it has to have something to do with the "smarts" of the gene.

    This is the only other kill switch the manual say:
    "Overspeed Shutdown"
    A DC control circuit board senses engine speed from the frequency of the alternator AC output. Should the alternator output frequency exceed ~72 Hertz (4,320 alternator rpm), circuit board action initiates an automatic engine shutdown.

    I don't hear a significant difference in engine speed (none in my opinion), but that board may be bad.

    Think it might be time to find a generator servicer.

    Thanks for all the advice.
  • RLS7201's avatar
    RLS7201
    Explorer II
    Aug 14, 2016
    Maybe a Kill A Watt meter should be your next expense? Then you'll know voltage and frequency at time of shut down.

    Richard
  • KD4UPL's avatar
    KD4UPL
    Explorer
    Aug 14, 2016
    Have you checked the vent on your fuel tank? If it's plugged you might be pulling a vacuum on the tank. The fuel pump eventually can't draw any more fuel.
  • gsf35099's avatar
    gsf35099
    Explorer
    Aug 14, 2016
    Well, after 2 1/2 hours of running great, I turned on the breaker and fired up both AC units. Within 3 minutes of running the AC's the generator shutdown.
    Turned off the AC's and left the breaker on, on the generator and it took 3 times of starting it back up and now its running again purring like it should. It shut down almost immediately on the first two tries. I think that was the voltage regulator still doing something because if the generator was overheating, then it would not still be running now. Has not had time to cool. From the time it died the first time to running now was less than 5 min.
    Been running great now for 15 min (as I type this) and going to let it run for another 30 min, then try the AC's one more time.
    If it shuts down again, I'm thinking it has to be the voltage regulator telling the Generator to turn off as its not working right.
  • gsf35099's avatar
    gsf35099
    Explorer
    Aug 14, 2016
    hottubkid wrote:
    Guessing gas filter???


    Thanks, but she is diesel and I've always stayed on top of replacing them. Plus it doesn't run rough or sputter when it dies, it dies like the kill switch is tripped or turned off. The longer it keeps running right now, the more I'm thinking its the voltage regulator turning it off. Should now here in another how as that is when I will turn on the AC's.

About Motorhome Group

38,705 PostsLatest Activity: Jan 20, 2025