Outboard Motor Blues

By Tom Neale

In case you're wondering (probably not) "OBM" is what we cool guys use when we're referring to an Outboard Motor.

Tom and the outboard motorTom and the OBM.

It makes us sound like we have some control and familiarity the things. We'll I'm here to confess to you today that I can't get my dinghy OBM running and I don't know why. I'm stumped.

Not being able to get one running isn't a big deal. We've all been there. Many times. But usually I can get it going after it punishes me enough. Or at least, I have a clue as to why it's not running, and that makes me feel better. Like, I just dropped it overboard. Or I forgot to run the gas out of the carb at the end of last season and there's a wonderful coat of varnish in the jets. Or maybe the spark wires got eaten by a rodent. There have been all sorts of reasons my outboards haven't run, but none of them fit this OBM at this time. I know I can get it to run given enough time, but how much cranking do I want to do and how much time do I want to take. If I didn't want to go for a dinghy ride I could have rebuilt the thing and maybe then it would have worked. But I didn't want to rebuild the thing and I really wanted to go for a dinghy ride.

It's a fairly new 20 HP Yamaha. It's been a wonderful motor and I'm sure it will again. I'm not complaining about the Yamaha; I've got two of them and I think they're both great ... except I'm having some reservations about this one at this time. At first I thought the priming bulb in the hose was bad. Sometimes the valves get gummed up or stopped up or eaten up or just plain crudded up. Then they won't prime. But this bulb was so hard I didn't even know whether it was priming because I couldn't begin to squeeze it. So I disconnected the OBM end of the line and pumped as well as I could and sure enough, there was no fuel coming out. AHH. Problem solved. And easily solved.

So I went down to my friendly "you can get everything you want" store and bought a new one by a reputable manufacturer. I bought the entire line assembly because you never know with all the ethanol our wonderful EPA is making us put into our gas as to whether the hose assembly or parts thereof will disintegrate and cause an explosion or, worse still, leak and cause a "sheen," all of which they don't want any more than I do.

The first thing I found when I returned to my dinghy was that this "assembly" wasn't compatible with my old Yamaha gas tank because that was an old fashioned tank and I had a new fashioned end fitting on my new line. That, I suppose, is why the assembly cost around $49.00. My multi-tool quickly took care of that issue (I won't say what I did). Fortunately, the assembly did fit at the motor end. Viola. I removed the cowling and pulled the onboard filter bowl and gas flowed through. (It hadn't before.) I reinstalled said filter bowl, pumped the bulb, gave the throttle the prerequisite jiggle, and cranked the engine. It started. Case closed. So I thought.

After running a couple of minutes the engine died with the symptoms of fuel deprivation. (It slowed down and slowed down and then died.) I checked the pickup tube in the tank, and even checked the spark plugs for good form, even though this didn't sound like that sort of a problem. Just for good measure I bypassed the outboard Racor filter, even though that was squeaky clean. None of this made a difference. The OBM wouldn't fire.

Another thing I can check is the fuel pump. But it's on the back of the block. Now that's a fine place for it to be if the engine is on a bench in a shop and you're standing there behind it. But you can't do that in a dinghy unless you pull the dinghy ashore and stand in the water — into which, incidentally, you'll drop your tools ... and the pump. And the water was cold. One can check the fuel pump after a fashion by removing its outlet hose from the barb where it goes into the carburetor and then cranking the engine. But you've got to hold or otherwise secure that disconnected hose so that any fuel coming out will go into a rag or other legally acceptable receptacle that meets appropriate legal standards (whatever they are). This is so that you won't get that sheen, assuming fuel comes out of the pump, which it probably won't. But this is very hard to do while you're pulling the starting cord in a dinghy that's bobbing in the water. I can only pull that starting cord with two hands and that's not conducive to controlling that little hose. I'll give it one thing: the daggone OBM does have good compression.

So, I gave up and lifted the dinghy back onto Chez Nous.

But not really, did I give up. There will be another day (when it's not so cold). I will try disconnecting the hose from the fuel pump. Sometimes their diaphragm or valves are impaired. Sometimes their drive is impaired. Sometimes the little filter screen (which should be inside) is cruddy. You never know. And I'll have help holding that rag or other legally acceptable receptacle to catch whatever gas may come out. If I get gas to the fuel pump from depressing the primer bulb but it isn't spurting out when I crank the engine that will probably be my answer. And if that doesn't work I'll go from there. One thing I could do would be to remove the carb but that would be a real pain and since the motor ran a little it probably wouldn't be the problem.

So other than whining, what's the point here?

Smaller outboard motors are still relatively easy for you and I fix. They still will probably run if you've got gas and spark. Yes, the gas has to have the right mixture with air and the spark has to come at the right time and be fairly close to the right quality. But this is relatively simple. To be sure, larger outboards are a lot more difficult for you and me to fix. They have onboard computers of a sort, they're much more complex, they will probably have fuel injectors and when you "look under the hood" they're nothing like the old outboard that you and I have grown up with. So, notwithstanding my temporary problem (and it will be temporary), do some tinkering, if you're so inclined, before giving up on the thing. I didn't get to take my dinghy ride, but I had some fun even though I'm not admitting it. 

Tom Neale, a technical and lifestyle writer and liveaboard cruiser. Read more of Tom Neale's articles here.

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— Published: November 2016

Tom's Tips: Troubleshooting Small Outboards

  • Pliers, a screwdriver or two, a few correctly sized wrenches and a multi-tool are often the only tools you'll need to trouble shoot and fix one, for most simple problems.
  • More complex issues such as testing the spark are best done not on the water but on the shore. This testing can be potentially dangerous.
  • I've found that most often the problem has to do with gas and that's where I usually start — but with great respect and caution.
  • All too often the fuel pump is the culprit if there isn't a more obvious solution. I'm not talking about a fuel pump for injectors but the "old fashioned" kind used with regular carburetors.
  • If you disassemble a fuel pump you'll probably find it a simple enough job, but watch out for tiny O rings, gaskets and valves. These can easily get lost, get out of order during reassembly, get inverted or be damaged. It'll probably take a while to get new parts.

See www.tomneale.com


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