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mikemc53's avatar
mikemc53
Explorer II
Jun 25, 2016

Electrical questions

I’ll try to get everything in some semblance of order in hopes that it might help sort things out.
Recently purchased a 27.5 ft 1993 Firan Telstar (on Ford E350 chassis) with 56K miles on it that had sat for a few years. Knowing that it has sat I expect to have issues and will be working my way through them but I’d like to start with some electrical things that I have just noticed. Some of these may be normal but I have no frame of reference (first MH) so I am looking for any enlightenment that might be available.

I started my probing with the generator, an Onan Microquiet 4000 with only 93 hours on the meter. The first time I attempted to start it I did not know if I should disconnect the shore power or propane or whatever so I left everything hooked up and hit the start button. As soon as I hit the button my propane detector started beeping so I shut the propane off and proceeded with the genie. It would crank but not start and occasionally it would just click but usually it would crank like crazy but not fire. I shot a little ether into the intake and it would fire but immediately shut down so I figured some kind of fuel issue and moved on (short on time and would get back to it later).

Well later was about two weeks later and this time I get only the rapid click (relay?) when trying to start. It won’t crank just clicks. So now I need to check if I am getting sufficient power to the solenoid but I have a couple of issues here. First I have no multi meter (long story but it is being replaced this week) so I just want to check connections, etc. I realized that I don’t know if the generator receives power to start from the chassis battery (brand new last week) or the coach/house batteries. As I worked through this it seems that it is the house batteries. Now here is how I came to that conclusion but tell me if I missed something. If I switch the battery disconnect to the off position I get nothing at all – no click, nothing. I started the vehicle and tried the generator and still nothing. When I turn the disconnect back on I get the rapid clicking. Now I know that there are two house batteries and though they look real clean they are probably a bit old. They run everything in the MH though if I disconnect from shore power and they seem to perform really well. Here is where I discovered a bit of an electrical oddity. We have a multi speed vent fan in the rear of the coach and since we have had it home we keep it connected to shore power all the time. The fan works on all speeds but is very loud so I figured in time I’d replace it. Today when disconnected from shore power I turned the fan on and it works great at all speeds with no loudness at all – it whispers. Hooked back up to shore power and it gets loud again. Not sure if this is normal but I wouldn’t think so.

OK, so I have the fan issue with the difference between shore power and battery. I have the generator no crank issue and I am unsure about whether or not it is getting sufficient juice to crank it. Also the fact that the propane sniffer beeps any time I hit the generator start button – not sure if that is normal or not. Once I get my multi meter I can check and see about the power but I am not sure exactly what to check and what to check it for. Is there a way to jump the generator from another vehicle or from the chassis battery? If I can start eliminating things one at a time I figure I can get something accomplished. I know that the house batteries are probably not new but they do seem to perform quite well when needed for other things. What is the best way to check the batteries? If they are good and I still get the click only, what is the next check?

Sorry for the windy and rambling post but there are a few issues that seem to be intertwined.
Class C
  • pianotuna's avatar
    pianotuna
    Nomad III
    Jun 25, 2016
    Hi,

    Not a good idea to start the generator when connected to shore power.
  • DrewE's avatar
    DrewE
    Explorer II
    Jun 25, 2016
    Typically the generator gets starting power from the house battery bank. The generator starter motor is often the highest current load these batteries would see by far, at least if you don't have a large inverter; my Onan starter uses somewhere in the vicinity of 100A, roughly speaking, when cranking. A weak battery or a poor connection (positive or ground) will quite easily result in low voltage at the starter. The starter clicking rather than cranking is pretty much proof positive of low voltage at the starter.

    The propane detector is probably going off because the system voltage is dipping; many are sensitive to low voltages. Unless it's a propane powered generator, there's no reason why starting it should make any propane flow or not flow.

    The generator's gas comes from the main fuel tank (again, assuming it's not a propane model). Typically the fuel pickup for the generator is at a quarter tank level, meaning the generator won't run if you have less than a quarter tank of fuel. This is to prevent you from accidentally running the tank dry with the generator and then not being able to drive to a gas pump.

    Sometimes the fuel lines deteriorate with age and get small cracks or pinholes that let air in. Sometimes the fuel pump in the generator fails. Sometimes the carburetors get gummed up if gas sits in them. Those are probably the most common fuel-related problems.

    On most of these generators, you can prime the fuel system by holding the control switch in the off position before starting it for several seconds (maybe half a minute). You should hear the fuel pump operate; it changes sound when the gas reaches the carb. The fuel line between the gas tank and the generator can be long, depending on where the generator is located, hence the need for the rather lengthy prime.

    It is possible to operate the generator from another battery by connecting it to the generator ground and battery plus terminals (the latter on the starter solenoid). Do be aware that the generator uses battery power to excite the generator field and run its control electronics while it is running and does not have a built-in battery charger. With the house battery, the converter charges the battery when the generator is running; but for some other battery, it will run it down sooner or later if nothing is done to charge it.
  • garyemunson's avatar
    garyemunson
    Explorer II
    Jun 25, 2016
    I suspect your house batteries need replacing. Drew's on the money with his suggestions about low voltage. Try Costco for the best price on 2 6 volts to connect in series. The batteries are not providing enough power to make your fan loud..when plugged in the converter provides the full 12 volts. If you have more than 1/4 tank of gas I'd suspect the carb on the generator needs cleaning or replacing.
  • Bordercollie's avatar
    Bordercollie
    Explorer
    Jun 25, 2016
    There is a ground cable from the generator to the RV frame that can get corroded and make poor continuity/contact. There may be a switch on the dash that connects the house battery and engine starting battery in parallel to help start the generator or the engine. That clicking sound with no cranking means that the generator starter motor is not getting enough power from the house battery which quickly runs down with attempts to start the generator. If your house battery and engine starting battery are both fully charged and you press the emergency start switch, the generator should at least crank rapidly for a short while. If you start the truck engine and let it run for a while then attempt to start the generator from the switch on the front of the generator it might start and run if fuel system is clear and you have more than 1/4 tank of fuel. The start switch on the front of the generator has less resistance than the remote wired generator start switches. You may have to install a new fuel filter and/or new carburetor. Generators need to be run frequently and for an hour or so or they become balky at starting, surge, etc. Run generator with no load for 10 minutes then turn on roof air conditioner and let run for an hour every month or so to keep generator reliable. Generator should operate the roof AC and microwave oven together if working properly. BTW, check cleanliness of connectors at your house batteries, remove any corrosion and tighten securely.
    Make sure connections at the converter/charger are tight and that house batteries are getting charge current from the converter charger. Keep electrolyte levels above plates in batteries with distilled water as needed.
    Being anal about 12 volt systems and generator is necessary for off grid operations. Most of the appliances rely on 12 volt power for electronic controls, your furnace blower must have 12 volt DC power.
  • DrewE's avatar
    DrewE
    Explorer II
    Jun 25, 2016
    luvztheoutdoorz1 wrote:
    A fuse on my generator will trip if I try to start it while connected to shore power.


    You have something wrong with the wiring of your RV, possibly something pretty dangerous. Check to see if you have 120V at the shore power plug when the generator is running (with a meter, not with your finger!). If you do, get your transfer switch replaced immediately.

    If it's a 12V fuse at the generator, it may be caused by the higher voltage from the converter as opposed to the battery. Check that the converter output voltage is in spec. If it is, there's something wrong in the generator as the 12V fuse should not blow under those circumstances.
  • mikemc53's avatar
    mikemc53
    Explorer II
    Jun 26, 2016
    OK, I checked the batteries (2 in parallel)on their own while not charging and they are at 13.3 volts. While trying to start the generator the voltage drops to 8.5. Not sure what this means but it seems like quite a significant drop.
  • ron_dittmer's avatar
    ron_dittmer
    Explorer II
    Jun 26, 2016
    mikemc53 wrote:
    OK, I checked the batteries (2 in parallel)on their own while not charging and they are at 13.3 volts. While trying to start the generator the voltage drops to 8.5. Not sure what this means but it seems like quite a significant drop.
    It surely sounds like you need two new house batteries. I also wonder if your 1993 converter is either bad or very sloppy in it's charging behavior. You might want to get it checked out, maybe replacing it with a current-day step-charging converter which is much easier on your batteries when plugged in for extended periods.

    DrewE is right on the money in all he wrote. Just adding a bit more here. With our 2007 model 4000 Onan, priming was very confusing until I understood what was going on. There is a light in our Onan start switch. When priming by toggling down in the off position, the light goes on after 5 seconds or so. It is then that it begins to prime which then I have to continue holding the switch in for maybe 10 seconds before trying to start the generator.

    The light going on does NOT mean it is time to try starting the generator. Just keep holding it in because you have just started priming the fuel line to the carburetor. Like DrewE says, if you listen closely, you can hear the fuel/primer pump running very quietly.

    PS: I love the 1993-1995 Firan Telstar line-up. They seem to be one of the best made rigs of that era. I'd love to see some pics when you get around to it.
  • cgmartine's avatar
    cgmartine
    Explorer
    Jun 26, 2016
    I agree that the house batteries sound like they need replacing, but if I could suggest...go with 6 volt Trojan batteries. You will not regret it. Make sure you have a full tank of gas and throw some Sea Foam in there. Check/replace generator spark plug, air filter, oil level, positive and negative cables, and carburator cleanliness.

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