Two-stroke and four-stroke outboards
Outboard motor service on Folsom Lake
An outboard is the easiest engine on the lake to get to and the easiest to keep alive if it gets serviced on a schedule. Water pump impellers, plugs, gear oil, fuel-system cleanup, and the annual once-over all get done where the boat sits, at your slip, the ramp, or the driveway. The mechanic we refer works on both two-stroke and four-stroke outboards, from small fishing kickers to the big four-strokes hanging off pontoons and bass boats.
The water pump impeller is the big one
If you remember one thing about outboard maintenance, make it the impeller. Down in the lower unit, a small rubber impeller pumps lake water up through the powerhead to carry heat away. That is the telltale stream of water you see coming out the side when the motor runs. The impeller is rubber, it spins every second the engine is on, and it gets brittle and sheds its vanes with age whether you run the boat hard or leave it parked. When it fails, cooling stops, the temperature climbs, and an overheated outboard can cook a powerhead in a hurry.
The fix is routine when it is done ahead of time and a disaster when it is done after the motor overheated. Plan on a new impeller every one to two seasons. On Folsom Lake, where a boat might sit for months and then get run hard on a hot July afternoon, that interval is not optional. A raw-water pump impeller job runs about $260 to $500 including parts and one to two hours of labor, and it is the single best value in outboard maintenance. If your motor is already running hot or spitting a weak telltale stream, stop running it and call before the heat does the expensive damage. More on how that number is built is on the boat repair cost page.
Weak telltale stream or a hot outboard? Describe it on the phone before you run it again.
Fuel, carbs, and the ethanol problem
The other half of outboard trouble is fuel. Modern ethanol-blended gas does not like to sit, and outboards sit more than almost any other engine. Ethanol draws moisture out of the air, and over an off-season it separates, gums up, and leaves varnish in the fuel system. On a carbureted outboard that varnish clogs the tiny jets in the carburetor and the motor will not idle, will not rev cleanly, or will not start at all. On a fuel-injected outboard the same stale fuel fouls injectors and sensors.
Carbureted outboards, which are still everywhere on the lake, need the carbs cleaned or rebuilt when this happens, along with fresh fuel and often a new filter and fuel line primer bulb. Fuel-injected outboards need the injectors and fuel system cleaned and the stale gas replaced. Either way the cure is the same idea: get the bad fuel out, clean what it fouled, and put a stabilizer in going forward so it does not happen again. A huge share of spring no-start calls are exactly this and nothing worse, which the won't-start page covers in order.
Plugs, gear oil, and the lower unit
Spark plugs are cheap and they matter. Fouled or worn plugs make an outboard hard to start, rough at idle, and weak under load, and on a two-stroke they foul faster than most owners expect. Fresh plugs are part of every annual service and often the fix for a motor that just feels tired.
The lower unit is the gearcase at the bottom of the outboard, and it runs in its own oil bath. That gear oil needs changing on a schedule, and its condition tells a story. Clean oil is fine. Milky, coffee-colored oil means water has gotten past a seal and into the gearcase, and water in the gears leads to corrosion and eventually a failed lower unit, which is one of the more expensive outboard repairs there is. Catching a bad seal early, when the oil first turns milky, is a cheap fix. Ignoring it is not. A mechanic pulls and reads the gear oil as a matter of course during service, which is one more reason the annual pays for itself.
The annual service prevents the breakdown
Almost everything above is on the annual service checklist: change the water pump impeller on schedule, replace plugs, change the gear oil and read it, clean or check the fuel system, add stabilizer, and inspect the fuel lines, primer bulb, and connections. Done in spring before the summer rush, it is a planned couple of hours. Skipped, it becomes a mid-lake breakdown on the one weekend you cleared to use the boat. On Folsom Lake the season is short and the shops are backed up all summer, so the smart owners get the outboard serviced before the queue forms. Annual service runs roughly $400 to $600 plus parts. Carrying the same habit into fall is what the winterizing and spring service page is about.
What this covers, and what it does not
The mechanics we refer service the outboard and its systems: cooling, fuel, ignition, the lower unit, and the annual maintenance that keeps it running. They do not do hull and fiberglass work, gelcoat, bottom paint, trailer repair, or anything that needs the boat hauled out onto stands, which belongs at a boatyard. If the problem is not the motor, you will hear that on the phone rather than pay for a trip to find out. If your boat is a sterndrive rather than an outboard, the outdrive service page is the right place to start.
Outboard service questions
How often should the water pump impeller be changed?
Every one to two seasons is the honest answer for a boat on Folsom Lake, and sooner if the telltale stream weakens or the motor runs hot. The impeller is rubber and it ages whether you use the boat or not, so time matters as much as hours. It is a routine job done on schedule and an expensive one done after an overheat, so it is not the place to stretch the interval.
Do you service both two-stroke and four-stroke outboards?
Yes, both. Two-strokes and four-strokes share the same basic service needs, impeller, plugs, gear oil, and fuel, with some differences in how they oil and burn fuel. Tell the contractor the make, horsepower, and rough model year when you call so the right parts and oil come along.
My carbureted outboard sat all winter and won't run right. What is it?
Almost always stale ethanol fuel that gummed up the carburetor jets. The cure is cleaning or rebuilding the carbs, replacing the old fuel and filter, and adding a stabilizer going forward. It is a common spring job and rarely the engine itself. If it will not start at all, the won't-start page walks through the checklist.
Why does the gear oil matter?
Because its color is an early warning. Milky or coffee-colored gear oil means water has slipped past a seal into the lower unit, and water in there causes corrosion and eventually a failed gearcase, which is one of the pricier outboard repairs. Caught early when the oil first looks off, replacing the seal is cheap. That is why a mechanic reads the oil during every service.
Can outboard service be done at the ramp or my driveway?
Yes, that is the whole point of mobile. Impellers, plugs, gear oil, fuel work, and the full annual service get done where the boat sits. Some tests want the motor run on a hose or the boat on the trailer, and the mechanic will tell you if so. Say where the boat is and whether it is in the water or trailered when you call.
Get connected with a local mobile marine mechanic for outboard service.