Did I damage my motor?

[hal1989]

Hi everyone,

I bought a boat (for the first time) with only 50 hours on a 2010 Suzuki df40 outboard. The fuel was was sitting for a while so I decided to flush it out the best I could. I disconnected the fuel line, connected ear muffs and let it idle. The water stream got weaker over time until it stopped completely (I assume because of low fuel). The only problem is that the engine still ran. I stupidly decided to let it keep running for about 5 minutes even after the water stream stopped.

Now, I am rethinking my choices! Have I screwed up the engine? I didn't hear any alarm bells from the motor.

(By the way, I reconnected the tank with new fuel and the outboard runs but the strength of the water jet seems to fluctuate from weaker to stronger and I'm not sure if that happened before)

Thanks for the help!

[Moonlighter]

The water stream strength has nothing at all to do with running the fuel out.

It is not a good idea to run an efi engine out of fuel, running the electronic fuel pump dry can damage it. Suggest you dont do it again.

These engines have excellent protection systems built in. If the engine had overheated, you would have heard a loud alarm. No alarm means there must have been enough water circulating to not overheat, or it didnt run long enough to get that hot.

So it is very unlikely that you have done any damage.

Now, getting back to the issue at hand.

You said the engine is a 2010 model that only has 50 hours on it? If thats the case, there is every chance that the water pump has never been changed and the engine may not have had its 12 monthly service. Impellers that have sat basically unused for that long WILL DETERIORATE BADLY, and that is most probably the cause of the weak and erratic water flow.

So the very first thing I would do is get a service done, including changing the engine oil and filters, drop the leg, check the thermostat, put a new water pump kit in, grease the drive shaft splines and change the gearbox oil. Check the internal engine anodes and replace if required.

In other words, do a full, standard 100 hr service on the engine as per the manual. Suzuki sells a 100hr service kit for each model that has all the parts needed, so even if you dont end up using them all (eg you might not change the spark plugs or anodes) you can keep them for next service.

Also, make sure you fit an external water separating fuel filter in the line between the tank and engine. A RACOR style filter is the go. Thse engines do not like water or dirt in their fuel and it is nasty and expensive to clean it out if it does get in. The extra filter is, in my opinion, a mandatory item to fit.

Lastly, the only muffs I recommend are the small round soft ones. They fit our Suzukis best and will provide a good water supply when flushing. None of the others are really suitable.

[hal1989]

Interesting! Your explanation makes sense with the fact that the engine stopped pumping out water when I had the fuel line disconnected suggesting that the impeller area needs to be looked at.

A week ago, I changed the lower unit oil and it looked very clean and the upper oil also looks pristine. I figured I didn't have to change the impeller too until the end of the season (I don't have much money so wanted to delay as much as I can), but I guess I was wrong.

The dealership said the boat was serviced last year in April. I will get a water pump kit installed and change the upper oil and filter as you say. To tell you the truth, I'm still thinking about the other stuff you mentioned because it sounds expensive but it might save me money down the road if I do it now.

Thank you for the information, I really appreciate it! I was worried there that I destroyed my motor.

[Moonlighter]

It very much depends on if you trust the dealership.

If they can show you a record of what was done 12 months ago, then the full service can probably wait. If not, then by doing a full service you at least know you have a good refrence point for future maintenance.

I know of water pump impellers that have sat unused for 12 months that got a set in them or dried out. No choice but to replace them, and always best to do a full water pump kit including the stainless backing.

Take careful note of what I said re the muffs - only use the small round ones. The others dont seal well enough and wont supply enough water. Keep the hose on full so there is plenty of pressure to the muffs. Never leave the motor while its running on the muffs, you need to watch it constantly.

The telltale is just that - it doesnt necessarily mean the water pump isnt working, and a small bit of rubbish can easily block it up. When the engine is running, poke a bit of heavy mono or weed eater line up there, dont be afraid to go in 6 or 8”, give it a wriggle around, and this often dislodges any lump of trash that is blocking it up and the water flow flushes it out.

You could maybe try that, along with the round muffs, before replacing the pump, and see what happens. I would still be suspicious of a 12 month old impeller thats been sitting in there unused, though, and given how important a good water flow is ........

Just to reiterate, the old 2 stroke days where we all disconnected the fuel lines after flushing the engine are long gone, because there is no oil in the fuel to dry out and clog up the carby. 4 strokes dont need this, and doing it on efi engines is a very bad practice.

[hal1989]

Thank you Moonlighter! I will report back with what I find.

[hal1989]

I took it to to the mechanic and I asked them to put in a new water pump and casing. They also greased joints etc. It cost me about 250, which was a lot higher than I expected. I wonder if it is easy enough to do myself?

I attached a pic of the old impeller, it seems a bit worn but not that bad. I think the problem of the jet stream being sporadic was probably because the water pressure wasn't high enough. Next year, I will do the full 100 hour Suzuki service.

[Murray]

I took it to to the mechanic and I asked them to put in a new water pump and casing. They also greased joints etc. It cost me about 250, which was a lot higher than I expected. I wonder if it is easy enough to do myself?

I attached a pic of the old impeller, it seems a bit worn but not that bad. I think the problem of the jet stream being sporadic was probably because the water pressure wasn't high enough. Next year, I will do the full 100 hour Suzuki service.

You can do allot of your own maintenance, you will need some quality tools, some mechanical abilities and a Suzuki genuine service manual. The Suzuki manual is a must, I’ve paid for mine 3 times over! You also have to be smart enough not to get in over your head, hence the manual. YouTube sometimes will give you a good starting point.