Woes with a new Yamaha 40HP fuel injected engine So here's the story thus far.

 In September 2013 we came to Beach Marine, in Jacksonville Florida, because we were not getting enough speed out of our late model 15hp Yamaha 4 stroke that came with the boat and it needed a new impeller. We decided to bite the bullet and upgrade to a bigger motor so we could get home to Virginia quicker, have a motor that can push us at about 8 knots, and so we don't have to pay an extra thousand or so in the Panama Canal which we will be traveling through later. If you can't make 8 knots, they charge you extra because you are delaying the canal.


Beach Marine was fantastic. They got us a new motor in a rush, fitted us in to their busy schedule, as well, and we got out in about four days. The cost was just over $8000 dollars. Much of it was labour, as there was cutting to fit the motor, redoing the steering to cater for the engine size, etc. What we didn't know is that the motor we thought was a 2013 model was actually a 2011 model. It had been sitting somewhere in a warehouse for two years prior to being sold to us.

I bought spares: two fuel filters, at around $20 each, two oil filters, oil etc. The sales guy guesstimated the propeller required a 12 pitch. We went with his recommendation. During the test run, during which we couldn't give full throttle as we were breaking it in, we got 8 knots one way and 8.5 the other. Pretty good. We were happy and impressed.

We took off and in a tight, busy channel, about 10 hours into the journey home, the engine randomly spluttered and died. Now, I had switched tanks shortly before and both tanks were clean and worked perfectly with the old motor for many miles. I figured one of two things; either some air got in the line or the filter was clogged. I pumped the priming bulb but that did not help, so I changed the filter. The engine fired up and away we went. About that time, I also changed the oil filter and the oil. Having been around engines a long time I know the worst thing you can do is not change the first oil on time. The running in process leaves much junk in the oil and if you want it to last, you change it not too early and not too late.

That motor ran about 50 hours after the filter change, and then did the same thing again. This time, in a channel with some wild current and it pushed us into the bank before I could get the anchor set. I changed the filter again. We were off, and luckily this was only sand, and we have a boat that is designed to be beached.

At about this point, the engine was run in, but we couldn't get more than 2400RPM out of it. We rang the guy who sold us the motor and he sent another propeller, a 10 pitch, to a marina, where we swapped them. We got more RPM but never saw the 8 knots that we did initially. At this point, we didn't care. What we wanted was to get home, and we could deal with the rest then.

Sure enough, about 50 hours or so after changing the filter we got the same problem again - this time, just after fueling up at a marina. The dockhand released the lines and we got just far enough out to be out of his reach before it died. The marina owner watched, in a panic, as we drifted towards berthed boats. He ran around to stop us hitting them. He just made it. I no longer had spare filters. I looked at it, and it looked perfect. I blew it out, and it had no real restrictions. There was nothing in the fuel/water seperator bowl other than clean non ethanol fuel. I put it back together and we tried again. The marina owner had a few of his crew spread around just in case we stalled again. We didnt, and we went for a while longer.

We went to another marina and the engine was fine. It had run for about 30 hours perfectly. This place had fuel filters. I asked regularly every time we fueled up if people had them. They are not that easy to find in some areas. I bought all he had, which was four filters if I remember correctly. I also bought a couple of small, inline filters, rated at 10 micron and put them in as well. Not that I was suspecting fuel anymore, but I also wasn't about to take chances. Off we went, a new filter in, and a new inline filter as well. That didn't help. We had the same thing happen several more times before we got to to our destination in Colonial Beach, Virginia and it happen again as we docked our boat at its final destination. The marina owner there asked me how the trip was and I told him it was fine, other than the damned motor failing at the most inconvenient places. We discussed it with his mechanic and neither of them, who were experienced in outboard service, had a clue.

I didn't work on the engine as I had more pressing issues to resolve: rusted steering, rusted mast mounts etc. We got back to the motor issue much closer to our departure time in March 2014. I ordered two brand new, plastic, 27 gallon tanks, new marine fuel hose to plumb them, and new vents to vent the tanks. I fitted a new Yamaha mini inline filter. The word mini here is misleading. This filter is big. Compared to the one on the engine, it is enormous. About 3 inches in diameter and 5 deep. I ordered two spare mini filters as well. The engine was serviced yet again. I'm rather anal about servicing engines. At this point, I only fitted one 27 gallon fuel tank but had the original Yamaha 6 gallon as well.

The trip from Colonial Beach to North Carolina was done with a friend, an ex submarine engine systems operator. We had several instances where the engine died on us. It was usually after running for a long time, then stopping for a few minutes, then restarting and taking off. In Manteo, it happened three times within an hour. The first had us drifting to rocks on shore, the second had us drifting towards boats in a fuel dock, and the third was just as we headed out of Manteo. The last was the longest to get started but, fortunately, we were in pretty deep water and a good distance from anything that wanted to kill us or destroy the boat. It happend again in the Albermarle Sound as I changed the 10 pitch prop to a 7 pitch. A five minute switch but far longer to get the engine started again.

We finally got to Surf City in North Carolina, with the engine intermitently failing and us getting, on average, 20 hours run time between events - sometimes a lot more and sometimes a lot less. The standard deviation was getting pretty wild at this point. While at our friends dock, we did the usual things: service the engine, fix things on the boat, and I attempted to find out what was causing the issue. I knew, by this point, it wasn't filter related. That engine has had so many new filters and inline filters replaced, it should be pristine internally, and later in the story we discovered that was, indeed, the case.
I checked the vent lines, checked the fuel lines for vacuum leaks, changed the priming bulb, changed the fuel lines connecting the mini inline filter to the engine, and even changed the line from the engine connector to the inline fuel filter. Nothing helped. I also fitted the second 27 gallon tank, while there, in case it was splashing so we could have at least one full tank and, thus, no way for splashing to occur.

We now had everything, except the fuel to engine connector, replaced, externally, many, multiple times. The issue was still pretty intermittent until we started getting further south. This could be due to the warmer weather or the warmer water temperature as the fuel system on this engine is water cooled. The problem started getting really bad in the lower end of South Carolina. By this point, it was failing regularly. Sometimes it would fail, run for a few minutes, and then fail again.
Going through Hell Gate in Georgia, we were in three foot chop with rocks on both sides in near gale conditions, and I was left priming the bulb every 30 seconds to get it to run. Then it would suddenly run for a full day with no problems.

We hit St Andrews sound during a gale while the Atlantic was pretty rough, so in that section, we were traveling in 6 to 8 foot breaking waves in gale force winds (41mph or greater), coming from the Atlantic Ocean, both of which were pushing us to the shallows at the dog leg turn there. Not much fun. Prior to getting there, the engine was running ok.

We had the engine stall a couple of times while waiting for bridge openings as well. Very embarrassing and frustrating. Finally, we got to the Marina where we bought the engine from, on Good Friday so needless to say nothing was going to happen till the following Monday.

The story continues since it involves more woes. This time with warranty.