generator won't start

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mikemc53

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Feb 28, 2014
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OK, this problem may have multiple tentacles but I will present what I have and see what we can come up with.

1993 Firan Telstar with ONAN 4000 Microquiet generator.

I bought the MH a few weeks ago and it had set for a few years at previous owners without being used. The generator has 93 hours total on it and, frankly, it looks almost new as it sits now. Oil changed and fresh - everything looks good. So here is what first transpired a few weeks ago when I just got it home: It would crank pretty readily but occasionally it would just click. When it would crank it would not start though I did get it to fire a couple times with ether but immediately it would shut down. I left it sit for a few weeks because I was working on other issues with it so that I could take a short trip - and that trip worked out fine with me never needing the generator.

Back home again and now the generator only clicks (relay for solenoid?) but won't crank. When I jump the solenoid I only get a hum but when I remove the jumper and hit the start it again only clicks.

Obviously I need to figure out the click/no crank issue first. After that we'll check the fuel delivery.

Thoughts?
 
Firing on ether but not continuing to run can come from two causes.  The first is the carburetor's fuel passages are plugged from sitting so long so no fuel is getting to the engine.  Or from a bad fuel pump, or a cracked fuel line that sucks air instead of fuel from the motorhome's tank.  This can be eliminated by substituting a short line sucking fuel from an outboard tank.

But if you get it to crank and fire, but the engine stops as soon as you release the start switch, one or more interlocks are shutting down the engine.

You need good oil pressure and voltage from the generator for it to stay running when you release the start switch.

Obviously, not cranking when you press the start button is a different problem.  I mentioned the above so you don't keep pulling out your hair after you get it to crank.

For the cranking problem, what happens to the battery voltage when it tries to crank?  Cranking takes a lot of current and if the battery isn't in top shape it may be able to run the normal low power loads like the lights, etc. but not have enough power to crank the generator.  Usually the generator is connected to the house batteries.

Same thing if you have a marginal connection between the battery and generator.  It won't pass enough to current to crank the engine.

The last thing I'd look at is the starter motor itself.  But only after you verify its getting good voltage while cranking.
 
Thanks Lou. I'm waiting on my multi meter (long story) but after I get it, what do I actually check with it? Am I checking at the battery posts (by the way there are two house batteries)? Do I check at the solenoid? I'm not sure where to check things so point me and hopefully I'll be OK.
 
When get the multimeter, set it for DC. 20 volt range.
The red lead will go to positive + pole on batt
The black lead goes to ground or - pole on batt.
Before cranking measure the voltage if voltage too low like 11v that is not enough voltage to crank.
As you are cranking the gen see how much voltages drop too. This may show a bad ground or battery does not have any power to crank.
If you are getting good voltage on the battery check the voltage on the solenoid, the multimeter should be digital so even if you have leads reversed it will show with a negative voltage . See if you are getting good voltage on solenoid.
 
Make sure you have at least a half tank of gas in the RV or otherwise the generator will not get any gas. It is designed that way so you cannot run the tank down so far with the generator you have no gas to get to a station. As far as not cranking check all of the battery connections and the house batteries since it is usually those that start the generator.
 
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.
 
Check ALL the battery connections.  Clean All connections both at the battery and at the frame, remove and reinstall. One at a time will help you not make a mistake $$$. Remove the battery ground wire from the battery for safety!! Make sure your not plugged into any 120 volt AC. I would also remove the ground wire at the truck battery also. Just like working on your car. (Helps to take pictures of the wires with your phone camera)
Common problem with generators is bad ground from the generator frame to the starter and from the generator frame to the motor home frame. This would explain the intermittent starting problem.  Also the low voltage when cranking.(Or trying to crank)
You likely have fuel problems also, but you need to fix the cranking problem first.

Keep us informed so we can help...step by step.
 
And feel the starter to be sure it is not hot, if it is then the windings may be shorted and that is drawing the voltage down due to what amounts to a dead short. The battery cables would be hot or warm also. Even warm would be a red flag since a generator should not draw much amperage to start.

A quick and easy way to check for a bad ground is to run a jumper cable from the generator ground to the battery ground directly. Regular automotive jumper cable. Pick a clean bare spot on the generator and go to the negative terminal of the battery. That eliminates any bad connections in the ground system. If it turns good then you know where to look.
 
Rickf1985 said:
A quick and easy way to check for a bad ground is to run a jumper cable from the generator ground to the battery ground directly. Regular automotive jumper cable. Pick a clean bare spot on the generator and go to the negative terminal of the battery. That eliminates any bad connections in the ground system. If it turns good then you know where to look.
Click to expand...

Not sure if my 22 ft jumper cables would reach but this is a  g-r-e-a-t  troubleshooting tip to check out vehicle grounds, generally.  Thanks for posting.  This one goes in my troubleshooting tips book under "Electrical....12v".  Gotta say......reading this forum is always, always time well spent IMHO.  For for best surface contact and most copper path, I'll probably use both sets of clamps ...... whenever there's enough room.
 
OK, I'm back.

Changed out the batteries, as after sitting with shore power unplugged for 3-4 hours the batteries were down to 10.5 volts. New batteries installed and the gennie cranks! And cranks, and cranks...no fuel to carb. I pulled the gas line to the carb and there is nothing coming through. I don't hear or feel the fuel pump working at all. Fresh oil, all connections seem really good, though I haven't really gotten to the fuel pump itself. Anything I should check before trying to pull the pump? It seems to be in an OK location to get at but I would imagine that the gas lines are probably pretty dried out and hard to remove.

Also I should note that this generator does not seem to have a priming feature. Some have said to hold the switch in the stop position but that doesn't do anything. I have the original manual and it does not speak to priming the generator. It only says to hold the start switch for 10 seconds. As I said, it cranks - really well - but there is no fuel to the carburetor. By the way, the fuel tank on the coach is almost full (7/8).

Thoughts?
 
mikemc53 said:
Anything I should check before trying to pull the pump? It seems to be in an OK location to get at but I would imagine that the gas lines are probably pretty dried out and hard to remove.

Thoughts?
Click to expand...

Mike- I just recently finished installing a new electric fuel pump and filter in my Microquiet 4000....much later year/model than yours, probably.... but I'd wager they are at least similar  The videos on YouTube were a big help.  Took just under 2 hours but it is painstaking work in that "tight" space.  In the YouTube search box, type Onan fuel pump replacement or similar words.  BTW- the shank of a 5/16 drill was a great "stopper/plug" for the fuel line under the coach where it enters the Genny box coming from the MH tank...... a little "force fit" and no clamp even needed.....don't think it leaked a drop while I did the work above.  BTW#2-  My Airtex electric pump and filter were just about $50 on Amazon.  Good luck with it, podnuh.
 
I don't know how good your lungs are but if you can have someone stand with their ear to the gas fill with the cap off and you blow into the gas line they should eventually hear bubbles if you are actually pushing the gas back. You may need to gently blow with a compressor. No bubbles means the line is not connected to the tank for whatever reason. I would get a short piece of line and run it from the pump into a gas can next to the generator compartment and set the can on a step so it is generally level with the generator and try that. Those fuel pumps are pretty expensive so you want to try the easy things first. Also check to see that the pump is getting voltage.
 
I tried that before on a truck years ago. There were bubbles on the tank when blowing with a compressor, but the line was only cracked, not broken completely. The truck still sucked air through the crack. Vacuum and pressure have completely different effects.
 
Very true, that is why I suggested the gas an approach. If the fuel pump is working and you are getting bubbles in the tank then you have at least narrowed it down to the right line and a good pump but no gas. Probably a cracked old line.
 
Rickf1985 said:
Make sure you have at least a half tank of gas in the RV or otherwise the generator will not get any gas. It is designed that way so you cannot run the tank down so far with the generator you have no gas to get to a station. As far as not cranking check all of the battery connections and the house batteries since it is usually those that start the generator.
Click to expand...
Hello Rick. I have a 95 Dolphin Rv that I just got going. I was having a problem with the generator not starting and I read your answer, thanks! Will the Gen shut off at 1/4 tank? It has been about 3.5-4 years since it has started, long story. Will gas it up and give it a shot!
 
Before attempting to start the generator, it would be very productive to remove the carburetor and give it a good cleaning. While you are there, replace the spark plugs, air filter and have new oil on hand for an oil change once the generator warms to running temperature.

The generator feed tube in the gas tank is normally about a quarter of the way from the bottom of the tank give or take. This is done so that fuel remains for the chassis engine .
 
Liuhisn said:
Hello Rick. I have a 95 Dolphin Rv that I just got going. I was having a problem with the generator not starting and I read your answer, thanks! Will the Gen shut off at 1/4 tank? It has been about 3.5-4 years since it has started, long story. Will gas it up and give it a shot!
Click to expand...
Rick hasn't logged in the site for 4 years.
 
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