That is the call we take most often, and on an Onan QG or Marquis set it rarely means the generator is finished. A no-run splits into three buckets - no crank, cranks but never fires, or fires and dies within a few seconds - and our technicians separate them in the first minutes because each one sends the job somewhere different. No crank points at the starting battery, the start solenoid or the start/stop control, and on most coaches the genset cranks off the chassis battery rather than the house bank, so a healthy inverter display tells you nothing. Cranks but never fires points at fuel delivery, the fuel pump or ignition. Fires and dies in about five seconds is the classic stale-fuel signature: the float bowl holds just enough to catch, then a varnished main jet cannot keep up. After any fault shutdown, holding the stop switch makes the panel lamp blink a fault code, which narrows it before a panel comes off.
Pump gasoline here is normally E10, and ethanol is hygroscopic - it pulls moisture out of humid tank air. Left past roughly three months it can phase separate, dropping a water and alcohol layer to the bottom of the tank and leaving the fuel above it short of the light fractions the engine needs to start. What stays behind in the carburetor is worse: gum and varnish that glaze the main jet, the idle circuit and the float needle seat, which is why a generator that ran fine in April cranks all day in September. The other half of our work is the opposite. Coaches that live here full time never get a winter lay-up, so hours accumulate all year with no natural service window, and oil, brushes and the spark arrestor quietly pass their intervals. Cummins Onan asks for the set to be exercised about two hours a month at half its rated load, and that habit alone prevents most of what we get called for.
We work the same sequence every time, cheapest and most likely first. Fuel level comes before anything, because the generator's pickup tube is deliberately set higher in the tank than the chassis engine's, so an Onan shuts down at around a quarter tank by design and the owner is not broken at all. Next is the blinked fault code, then engine oil level, since the low oil pressure switch will stop the set and hold it stopped. Then comes fuel delivery at the pump and the carburetor bowl, which we drain to look for water and varnish, followed by spark at the plug. Only then do we go electrical: no-load AC output on a Fluke 87V multimeter, where we expect roughly 120 to 126 volts and about 60 to 62 hertz. Frequency gets read before voltage, because it reports engine speed, and speed and output are two different repairs.
Yes, and on these sets it is the service that buys the most life for the least money. These sets hold only 1.6 to 2 quarts depending on model, so a neglected one runs low quickly and trips its low oil pressure shutdown. In Florida heat our technicians normally fill with 15W-40. The same visit covers the air filter, the spark plug, which Cummins Onan gaps at 0.025 in, and the spark arrestor screen, which loads up with carbon and chokes the exhaust long before anyone notices. Onan's periodic maintenance schedule puts the oil change, the air filter element and the spark arrestor cleanout on a 150 hour cycle, and a coach that never lays up for winter reaches that mark on the hour meter long before the calendar suggests it should. The arrestor itself is not a teardown either. Two cleanout plugs come out of a cooled muffler, the set is run briefly to blow the carbon clear, and the plugs go back in.
When the engine runs perfectly but nothing comes out of the outlets, the fault is usually in the generator end, not the engine. Two carbon brushes ride on the rotor's slip rings and carry the field current, and as they wear they shorten, lose spring pressure and shed conductive dust that bridges the rings. Our technicians pull the brush block, measure remaining brush length against the wear line, check that the springs still load them squarely, and read rotor resistance across the slip rings to prove the field winding is neither open nor shorted. Grooved or glazed rings get polished with crocus cloth, never emery, because aluminum oxide grit embeds in soft slip-ring metal and destroys the next set of brushes. On most Class A and C coaches the genset has to come out on its slide tray first - four mounting bolts, the fuel line and the harness - which is why this is a two to four hour job, not a thirty minute one.
We give the honest answer, because a rebuild sold on a worn-out block helps nobody. If the hour meter is low, compression is healthy and the set has simply been sitting, it is a service: clean or replace the carburetor, fresh fuel, oil, filters and plug. If the engine is sound but the fuel pump, carburetor and brushes have all reached the end together, a staged rebuild is usually worth it, since those parts typically run from around $40 to $90 for a brush kit, $60 to $400 for a carburetor depending on aftermarket or OEM, and $120 to $250 for a fuel pump. Replacement is the call when compression is down, the set burns oil, or the repair total starts approaching what a new 4 kW unit costs installed. Left alone, a varnished carburetor becomes a burnt exhaust valve, and worn brushes become scored slip rings and a rotor, which is a cheap part turning into an expensive one.
We are fully mobile and come to you anywhere in Florida - campgrounds, storage lots, driveways and RV parks.
Call 888-759-1438Yes, both, and often on the same visit. Our technicians service Onan QG and Marquis gas sets and Quiet Diesel units, and we also handle rooftop air conditioners, which matters because the two faults look identical from the driver's seat. A generator that will not carry the air conditioner can be a weak genset, a failing AC compressor or a soft-start problem, and testing both together is the only way to know which one you are actually paying to fix.
Yes. On Onan QG sets the electric fuel pump is a common failure, and the symptom is usually cranks but never fires, or runs for a minute then quits as the bowl empties. We confirm it before replacing it by listening for pump click at the start command and testing delivery, because a varnished carburetor produces the same symptom.
We do test loose and removed sets, and we will tell you up front when it is worth the money. A bench test shows whether the engine runs and whether it makes rated voltage and frequency, but it will not reproduce faults that only appear under real load in the coach. If the set is still in the RV, testing it in place with a load applied gives a far more useful answer for the same money.
Usually yes. On Onan Quiet Diesel sets most leaks we find are fuel return lines, injector seals, the fuel filter head or the lift pump, and oil leaks tend to be the filter adapter or a valve cover gasket. We locate the source by cleaning the area, running the set and watching where it wets, rather than guessing from where the puddle lands. Leaks left alone soak the sound insulation, which becomes a fire concern as well as a repair.
Our service call covers the trip out and the first hour on site at the rate in the pricing table on this page; anything past that first hour is quoted and approved before we carry on. We will not quote a fixed price for a generator we have not seen, because a set that needs a carburetor and a set that needs a rotor sound identical on the phone.
Plan on oil and filter every 150 run hours or annually, air filter and spark plug on the longer interval, and a look at the brushes and spark arrestor screen once a year. Florida coaches that never lay up for winter reach those hour marks faster than the calendar suggests, so we go by the hour meter, not the season. Exercising it about two hours a month at half load is the cheapest maintenance there is.
Every figure on this page comes from a manufacturer document or a standards body, not from another repair site. Here is where each one comes from.
| Item | Price | What it covers |
|---|---|---|
| Service call | $299 | Includes the trip out to your RV and the first hour on site |
| Work past the first hour | Quoted after diagnosis | We tell you what it will take before we carry on |
| Parts | Quoted per job | Special-order parts may need a deposit before we order them |
| Written estimate | No charge | You approve the estimate before any work starts |
The service call covers the trip out to your RV and the first hour on site. Anything beyond that depends on what we find, and we quote it and get your approval before carrying on.
The price ranges on this page come from our own recent jobs across Florida, not from an industry average. What you pay depends on the rig, the parts it needs and what we find on site, so we give you a written estimate before any work begins and you approve it first.