Mobile RV Generator Repair Across Florida

Why will an RV generator crank but not start?

Almost always fuel delivery, and almost never the engine itself, because these engines do very little work for the hours they log.

The most common cause in this state is a carburetor left standing with fuel in it. Modern gasoline separates and gums the small passages in a carburetor within months, and a generator that sat through a Florida summer unused is the classic case. It cranks, it has spark, and nothing reaches the cylinder.

The second is the fuel pickup. Most gasoline sets draw from the coach tank through a tube that stops well above the bottom, so the generator runs out of fuel while the dash gauge still reads a quarter tank. That is a design feature rather than a fault, and it strands people regularly.

The third is the start battery circuit, which on many coaches is not the battery owners assume it is.

What does it mean when the generator runs but nothing works?

It means the engine is fine and the fault is somewhere between its output terminals and the coach panel.

This is the single most misdiagnosed generator complaint, because from inside the coach it is indistinguishable from a dead generator. The engine noise tells you the mechanical side is working, and nothing else about the situation is visible from the living space.

There are four candidates and they separate quickly. The generator's own circuit breaker may have tripped, which is a reset. The voltage regulator or the windings may have failed, which is a repair at the set. The feed cable may have failed. Or the automatic transfer switch may not be handing the supply over.

One measurement at the output terminals separates the first two from the last two, which is why it is always the first thing done.

How does the transfer switch fit into this?

It decides which supply reaches the coach, and it fails quietly enough that the generator gets blamed for it.

Shore power and generator power both pass through this one part, and it holds one set of contacts closed while the other stays open. That interlock is a safety function: it is what stops a running generator back-feeding a campground pedestal.

Its signature failure is partial power. On a fifty-amp coach it carries two legs, so one set of contacts can burn out while the other still makes, and half the outlets keep working. A burnt smell in that bay is a reason to shut everything down rather than to keep testing.

Most automatic switches also delay before handing over, so a generator started and shut off again within that window looks broken when it is not.

What does Florida do to a generator that sits?

Heat, humidity and long idle periods, and the idle periods do more damage than the running hours.

A set that runs regularly circulates fuel, keeps its carburetor wet and keeps a film of oil on the cylinder wall. One that sits for six months does none of those. The fuel separates, the carburetor gums, moisture collects in the crankcase and rodents find the wiring loom, which in this state is a genuine and frequent failure mode rather than a joke.

The cure is running it under load once a month for a reasonable stretch. Under load matters: idling a generator with nothing switched on does not warm it enough to drive off moisture and can glaze the bore over time.

That single habit prevents most of the calls we run in the spring. It is also the cheapest maintenance on the coach.

How often should an RV generator be serviced?

By hours rather than by years, and the hour meter is the number to work from because coaches vary enormously.

The service items are oil and filter, air filter, spark plugs and the fuel filter, and the manufacturer publishes an interval for each. A full-timer running air conditioning off the generator daily will reach those intervals in a season; a weekend owner may take several years.

What is not on the hour meter is the annual work. The exhaust and its mounting need inspecting for corrosion regardless of hours, because a leaking exhaust inside a coach bay is a carbon monoxide problem rather than a performance one.

Manufacturer schedules for the common sets are public, and we work to them rather than to a generic interval. Working to the published schedule also matters for any warranty still in force, since a service history is what a claim is judged against.

Is a generator worth repairing on an older coach?

Usually yes, because the parts that fail are the serviceable ones and the expensive assemblies rarely wear out first.

Carburetors, fuel pumps, starters, control boards, regulators and brushes are all replaceable, and none of them is close to the cost of the set. Engines and alternator windings do fail, but they are the minority of what we find when a generator stops.

The point where the argument changes is a set that has been sitting for years with unknown history. Once you are replacing a carburetor, a fuel pump and a control board on the same visit, the arithmetic starts to favor a replacement unit.

The other honest consideration is noise and weight. Owners replacing a very old set often want a quieter or inverter-type unit anyway, and that is a legitimate reason on its own.

What about carbon monoxide and where the generator vents?

It is the part of this job that is not negotiable, and it gets checked on every visit whatever the complaint was.

Generator exhaust has to leave the coach and stay left. A corroded pipe, a loose clamp or a cracked manifold inside a sealed bay puts combustion products where people sleep, and carbon monoxide has no smell to warn anyone. Coaches are also frequently parked with the exhaust facing an awning or a neighboring rig.

The detector is the second half of it. Carbon monoxide alarms have a service life of their own and expire whether or not they have ever sounded, and we find expired ones regularly.

Any generator fault that involves the exhaust stops being a convenience repair at that point, and it is treated accordingly. Replacing an out-of-date alarm costs very little and is the last thing anyone should defer.

What should you check before calling us out?

Four things, and any of them can turn a service call into a five-minute fix you do yourself.

Check the fuel level against the quarter-tank cutoff, because a generator that stops at a quarter tank is behaving exactly as designed. Check the generator's own circuit breaker, which is on the set rather than in the coach panel and is easy to miss.

Then start it and wait a full minute before deciding nothing happened, because the transfer delay is normal. Finally, look for a burnt smell or discoloration in the transfer switch bay - if you find one, stop and leave the coach off both supplies.

Our generator troubleshooting guide works through the same order in more detail, and our electrical service covers what sits downstream. Between them those four checks resolve a real share of the calls that come in as a dead generator.

Generator questions RV owners ask us

Sources

• Cummins Onan - RV generator set manual - Manufacturer service intervals, fault codes and shutdown behavior for the common RV sets.
• Cummins Onan - quick start and exercise guidance - Manufacturer guidance on exercising a set under load rather than at idle.
• OSHA - electrical hazards - Background on working near energized conductors, which is what output diagnosis involves.
• US Fire Administration - fire prevention - Why exhaust and fuel-system integrity in an enclosed bay is a safety matter, not a performance one.