25hp Honda Outboard Won't Start

[joburnet]

It's a 1997 model 25 HP four cycle short shaft outboard with a pull start. I've had this engine for a little over a month now and never had a problem with daily use. I've been using it on my dinghy which is a 16' aluminum fishing boat. I came to shore the other day around 10a.m. with no problems and shut it down like usual. When I was going to go back to the boat around 1p.m. it just wouldn't start. I tried for about a half hour playing with the choke and throttle and eventually gave up and hitched a ride to my boat. I've done the same basic thing twice more with no luck.

The engine doesn't seem to be getting fuel. I can crank on it for a while and I don't smell gasoline and if it was getting fuel it would cycle it through the engine and out the exhaust where it would end up on top of the water and quite pungent. Does anyone know how the low oil shutdown or emergency shutdown works? If either of them shuts off fuel flow then that may be the issue. I checked the oil and the oil level is about half way up the dipstick, not sure what proper oil level is on this engine. Thanks.

[joburnet]

Anyone have a suggestion? My best guess is a fuel pump but this is my first time working on an outboard so help would be appreciated.

[FSMike]

The first thing I would do is make sure the oil is at the proper level. If that model has a low oil shutoff that may solve the problem, and if not the oil should be topped up anyway. How long has it been since you changed the oil?
My best guess is a carburetor problem, possibly dirt or a buildup of residue in the jets, so clean the carb, might as well stick in a rebuild kit. On general principle put the gas in the tank in your car and get some new gas for the outboard. Clean the outboard tank before loading up the new gas. Use a gas treatment religiously if you haven't been.
Make sure the spark plug is in good condition and sparks when you try to crank it. When things like this happen to me I replace the plug automatically.
While you're doing all this make sure everything is connected properly, i.e. fuel lines, electrics, throttle linkage, etc. It's embarassing to find out the problem is due to your spark plug wire falling off. You do have the plug in the kill switch?
Beyond this seek out somebody knowledgeable in your area.
Good luck.

[joburnet]

I'm going to download the owners manual tomorrow when I get a ride to shore and get the model number. Is there a manual that shows how do take the carbs off and clean them or is it pretty self explanatory? Why they would put three carbs on one engine is beyond me.

This sounds like a dumb question but how do you change the oil in an outboard? Is there a drain plug or do you suck the oil out of the fill hole?

[FSMike]

The Honda shop manual (as opposed to the owner's manual) shows how to do pretty much everything. It isn't cheap and may have to be ordered. Prior experience is helpful, such manuals presume at least some training. That said, as long as you put things back together properly so you don't make the situation worse you might as well give it a try. If you can get a copy of the parts microfiche (exploded diagram) for the carb it will be a huge help. Might be on the internet or perhaps you can sweet talk a dealer.

I wasn't aware that model has three carbs. That reduces the chances of it being a carb problem. Check the spark first. If you don't have spark to all three plugs you have some sort of electrical failure in the system. If it's a fuel delivery problem it has to be something that affects all three carbs. It's still possible to have dirty/gummed up carbs, but less likely. I once saw a diagnostic problem that went on forever until someone noticed that a large tank had been put on the top of the fuel line.

The engine needs spark, fuel, and air. Without those it won't run. It also needs those things to happen at the right time, as well as compression, but let's not get too complicated. If you have a friend in the area with mechanical experience to help in the diagnosis that sure would be convenient.

Anybody else got any ideas?

[S/V_Surya]

I also have a 25 honda outboard about same vintage. I am an expert at removing and rebuilding carbs on it after spending a week doing so (multiple times). I do not think that is your problem. Try starting fluid to make sure it is fuel problem. Does it even try to crank? Rebuilding carbs is pretty staight forward. First get gaskets and jets from dealer. Remove manifold (6 bolts)and then unbolt carbs (2 bolts each). Remove linkage make sure you remember how to put back together. Before rebuild it was very hard to start now after setting for winter it is 2 or three pulls. If starting fluid does not even get it to attempt to crank then I would say it is part of the kill system problem. Note: I also added a large pre filter fuel filter to make sure fuel is clean.

[joburnet]

Thanks for the input but when I got back to it this morning it started after about 5 pulls. I'm still thinking the fuel pump is the problem since they can be intermittent but who knows. I'm going to rebuild the carbs, change the oil and fuel filter, and then see what I think. If the fuel pump is cheap I'll just replace it anyway.

[joburnet]

Engine is still running fine. I called the Honda dealership to ask about a fuel pump and the parts guy said that the likely problem is water in the gas tank. This makes sense since it's so humid down here. The solution is to put some isopropal alcohol which will dissolve the water and to use non-ethanol gas.

[joburnet]

Found a nice little article about ethanol in small engines and how the water seperates out if gas sits for a while which is what probably happened to me.

" 'I wish they'd give us our old gas back.”

That's the consensus from local small-motor mechanics, including John Ferullo, owner of Advanced Power Equipment in East Lyme, who have been seeing a major influx in business over the past few years, ever since the state started mandating ethanol in the gasoline sold in Connecticut.

Ethanol, often made from corn sugars, is a colorless alcohol fuel that, by law, makes up 10 percent of the product dispensed at Connecticut gasoline pumps.

Ethanol makes a mess of small motors, such as the lawn mowers, snow blowers, trimmers, chain saws and leaf blowers that Ferullo's shop services.

”It's driving us crazy,” said Ferullo. “Now it's to the point that seven to eight machines out of 10 that we service have fuel issues.”

Ethanol messes with smaller engines because of its tendency to attract moisture over time, local mechanics said. The result is that carburetors get clogged with a crusty film that must be cleaned out if gas is left in the machine too long - and, in some cases, the carburetor must be replaced entirely.

”The fuel goes stale quickly,” Ferullo said. “It turns into a kind of shellac in the carburetor.”

If left over a long period, gasoline, oil and ethanol will start separating from one another in the gas tank and the whole carburetor body of a smaller motor will start corroding, mechanics said. With oil sinking to the bottom, the engine may not get proper lubrication, he said.

In the past, letting gas sit in a machine with a small motor wasn't a problem, but now homeowners are looking at a big repair bill - about $100 for lawnmowers -

Average repairs on motorcycle engines with carburetor problems run $150 to $200."