New Suzuki 15hp outboard update

[cardude01]

I purchased a new Suzuki DF 15A fuel injected outboard a few months ago, and finally got to try it out on the dinghy this weekend. I also got to try out the new dinghy lift using the boom and block and tackle and the new outboard crane I installed with Healhustler a few weeks ago.



I mounted the dinghy upright on some homemade chocks, and I can use the topping lift line to raise the boom up enough to lift the dinghy high enough to deploy it over the side. I can do this single handed without too much effort, so I was happy with the setup. I did it in the calm harbor with no wind. Don’t think it would be too much fun to do in higher winds and chop however.

I was able to tie off the dinghy to the stern of the boat, get inside the dinghy and operate the outboard crane to easily lower the outboard onto the transom. I was pretty worried about the harness I installed on the outboard slipping off, but it went well.

I broke the engine in slowly for the first three hours as manual recommended with no throttle above 1/2 RPM. I was amazed how quiet the outboard was and how smoothly it idled, and how quickly it planes for a 10’ RIB with just me in it. I did install a tiller extension so I could move forward some. It also started on either the first or second pull, and that was great since the main reason I got it was so my wife, kids, basically anyone who wanted to use the dinghy could actually start the engine. It’s fuel injected but with no battery to keep the weight down a bit (97 lbs), and even though the first pull can be tough with the compression, I learned if you first pull the cord tight against the compression and then give it a tug it won’t jerk the handle out of your hands. It doesn’t take much effort once you learn that trick.

The only issue I have is it seems to surge some at high RPM. After break in I ran it up to close to full throttle momentarily, and it started to surge quite a bit. I’ve looked on the web for answers and many have had some surging problems related to clogged internal fuel filters, air leaks in the fuel system, and other air fuel related issues. I will hunt around to see if I can find an easy fix, and if I strike out I guess I will take it to a Suzuki dealer. Anyone experience any surging like this?

https://youtu.be/Zn8MLwur_R4

 

[Russell Clifton]

I have the same motor. There are three safety features on this motor to protect from over-revolution, low oil pressure, and over temp. In all three cases the rpm will drop when one of these three problems occurs.

If your oil level is good and there is lots of water coming out the pee hole, than maybe it is over revving due to the wrong prop for your application.

When it starts to surge, cut back on the throttle and see if it goes away. If so my bet is the prop is wrong for your boat. Good luck.

 

[DavidM]

Davis makes an outboard harness that is secure and will lift your 15 hp. see https://www.amazon.com/Motor-Caddy-Outboard-Hoist-Harness/dp/B001447NTC

David

 

[cardude01]

I have the same motor. There are three safety features on this motor to protect from over-revolution, low oil pressure, and over temp. In all three cases the rpm will drop when one of these three problems occurs.



If your oil level is good and there is lots of water coming out the pee hole, than maybe it is over revving due to the wrong prop for your application.



When it starts to surge, cut back on the throttle and see if it goes away. If so my bet is the prop is wrong for your boat. Good luck.

Oil good. Lots of water shooting out.

I was wondering if it was a rev limiter situation. When I let off on the throttle it immediately stopped. Should I change props or can I just make sure not to hit the rev limiter by not running at full throttle? I don’t even know what prop came on this thing. How do I know what it should have for my boat?

Also, I was solo when it did this surging so maybe the boat wasn’t loaded enough? Maybe I need to try it with two people in the boat?

Don’t want to blow it up!

My boat is a West Marine RIB 310.

 

[cardude01]

Davis makes an outboard harness that is secure and will lift your 15 hp. see https://www.amazon.com/Motor-Caddy-Outboard-Hoist-Harness/dp/B001447NTC

David

That’s actually what I put on it, but the engine was too fat so I had to buy a longer strap to go around the lower part of the engine. Seems to be Ok I guess.

 

[kchace]

That engine certainly does have a rev limiter - its very possible with you forward in the dinghy at WOT it was hitting the limiter, especially if it stopped "surging" immediately when you reduced throttle. The fact that it seemed to plane very quickly, the prop may have a bit too little pitch for your use. There are like 5 available prop pitches for that motor and they ship with like the middle one. Of course going up in prop pitch (to reduce WOT RPM) will also have the effect of making it take longer to plane. If it were mine, I'd live with it for a while and see how it performs overall.

One other note, the rev limiter should not allow the motor to exceed a safe rpm.

Ken

 

[seasalt007]

If I were you I would put a Doel Fin on it so you don't have to sit forward. It will come on plane in a pretty level attitude with the fin. My 15 hp on a previous AB 9.6 would raise its bow and make you think it was going to flip over backwards when you gave it the gas. The fin stopped that.

You picture doesn't show one on the motor best I can see..

https://www.amazon.com/Davis-Instruments-Hydrofoil-outboards-Outdrives/dp/B076GWYTYV

 

[Russell Clifton]

Your prop will have the size and pitch engraved into it so if you were going to change it you have a starting point.

Good idea to wait awhile and kind of get the feel of it. It could be it will be fine with another person in the boat. Of course there is no need to operate it wide open all the time.

The hydrofoil will make a big difference. It will get up on a plane much faster and will plane at a lower speed. You will also be able to operate the boat from the back seat without it porpoising. I have them installed on both my tenders. It is a bit difficult to get the holes drilled as you can't get a strait shot with the drill motor.

In my case I had to actually change the prop to one with more pitch as most of these motors here in the northwest are sold for trolling motors used on 18-24 foot fishing boats and the dealers order them with a high thrust prop. My boat would not get up on a plane even with the hydrofoil. I found a new prop online for about $50.00

 

[High Wire]

Instead of guessing, borrow a handheld photo tach and measure the rpm just below the point of surging. Is it close to redline? I doubt it. My guess is an air leak in the fuel line connections.

 

[Dougcole]

Interesting info about the compression causing the starter cord to bind. My 20 hp Suzuki, which is the same motor as the 15, does the same thing. It's impossible to predict, sometimes it happens on the first pull, sometimes the 2nd or 3rd, sometimes not at all. It generally starts within three pulls.

When it binds it will dang near pull your arm out of the socket, it's no fun at all.

I took it back to my dealer, Shields Marina in St. Marks, who I consider to be the best in the business, and they couldn't figure it out.

I've tried your trick, but like I said, sometimes it pulls perfectly the first time with no compression binding it, so I can't really "pull against it" as you suggest.

I've just been living with it.

I've owned a ton of outboards in my life and this one isn't my favorite, honestly.

 

[cardude01]

Instead of guessing, borrow a handheld photo tach and measure the rpm just below the point of surging. Is it close to redline? I doubt it. My guess is an air leak in the fuel line connections.

That’s a good idea. Thanks.

 

[cardude01]

Interesting info about the compression causing the starter cord to bind. My 20 hp Suzuki, which is the same motor as the 15, does the same thing. It's impossible to predict, sometimes it happens on the first pull, sometimes the 2nd or 3rd, sometimes not at all. It generally starts within three pulls.

When it binds it will dang near pull your arm out of the socket, it's no fun at all.

I took it back to my dealer, Shields Marina in St. Marks, who I consider to be the best in the business, and they couldn't figure it out.

I've tried your trick, but like I said, sometimes it pulls perfectly the first time with no compression binding it, so I can't really "pull against it" as you suggest.

I've just been living with it.

I've owned a ton of outboards in my life and this one isn't my favorite, honestly.

Oh yikes. Mine didn’t seem to jerk that hard, but now I wonder if it will jerk too hard for my wife— she’s pretty little.

Have you experienced any of the surging at high RPM?

 

[Dougcole]

No, no surging at high rpm. I got my motor new in 2013, it's been mostly good.

I've had a few issues with fuel, one of which was self inflicted (hose popped off of the tank and sucked rainwater into the motor from the bottom of the dinghy). Last year after I put the motor away for 7 months, the high pressure injector pump, a $450 part, failed due to bad fuel. I used stabilizer but that load of fuel came from the Bahamas, so it may or may not have had ethanol in it.

I try to never run any ethanol fuel through either of my two outboards but sometimes I don't have a choice. This year I poured the Bahamas fuel into my truck, bought a gallon of non ethanol stateside, stabilized it ran it in the motor for a while then ran the motor dry before I put it away. I started it up a few weeks ago and it fired right up by didn't want run at the lowest idle. Who knows.

When it runs right it's great. Quiet, pretty strong, starts on one or two pulls. I don't love it, but I don't hate it either and I don't know that there is a better alternative.

 

[cardude01]

Thanks Dougcole,

I read somewhere that because there is no air in the EFI system that oxygen couldn’t get to the fuel, so it couldn’t go bad? I still stabilized the fuel out of habit however.

I think I read in the Suzuki manual not to run it dry because it could harm the high pressure pump.

 

[FlyWright]

Looks great, Bill. Is that a Garhauer davit? I love mine.

Take a friend along next time, preferably a large friend, to see it the rev limiter still kicks in and note the change in planing performance. You might find you're just right with a normal load of 2.

+1 on the Doelfin/Whale Tail if the stern squats too much with one aboard. They are very effective.

 

[Dougcole]

I've heard both things now on running it dry. The dealer told me not to, and I didn't do it before the pump failed. The mechanic who repaired it told me to run it dry.

I hate it when it is unclear, I'll take a look at my manual.

The fuel in my system was definitely bad, so I'm not sure the air thing holds water. (bad pun, sorry).

 

[Benthic2]

As you empty a gas tank, air has to get in. So the gas in your tank is exposed to air.

 

[cardude01]

Well there you go, bringing logic into the discussion. [emoji23]

 

[CheckMateTim]

Ever figure it out? I, too, have the same engine and it's stumbling at higher rpm and left me stranded this past weekend. It would start, idle and then just stop.

 

[O C Diver]

Ever figure it out? I, too, have the same engine and it's stumbling at higher rpm and left me stranded this past weekend. It would start, idle and then just stop.

The stumbling or surging at WOT usually indicates the rev limiter. Changing the propeller to a higher pitch should solve your problem. It's on my list of things to do. Leaving you stranded may be another problem. The computer measures oil pressure, temperature, and time. So it will tell you when the engine needs an oil change, has low oil pressure, has high operating temperature. Usually those items don't shut the engine down, but limit it to low RPM. Might want to check the owner's manual.

Ted

 

[CheckMateTim]

The stumbling or surging at WOT usually indicates the rev limiter. Changing the propeller to a higher pitch should solve your problem. It's on my list of things to do. Leaving you stranded may be another problem. The computer measures oil pressure, temperature, and time. So it will tell you when the engine needs an oil change, has low oil pressure, has high operating temperature. Usually those items don't shut the engine down, but limit it to low RPM. Might want to check the owner's manual.

Ted

Hi Ted,
I did get it back up and running but still not completely 100% here. It still occasionally stumbled on top end (I will get a new prop --- do you happen to know the next size it needs?) I'm assuming I need a bigger prop? Hitting the rev limiter?

oh and my instances happened right after new gas..... not sure how much, if any, that plays a role in any of this.

 

[O C Diver]

Propeller pitch for Suzuki 15 HP generally range from 7" to 12" of pitch,the diameter remains the same. If memory serves me, the stock propeller is 10". It's marked on the propeller. If it's 10" an 11" is 10% more, but pushing your boat faster could take significantly more than 10% more HP. So it's a bit of a guess. If you have a 10" pitch, I would probably only go up 1".

Ted

 

[CheckMateTim]

Propeller pitch for Suzuki 15 HP generally range from 7" to 12" of pitch,the diameter remains the same. If memory serves me, the stock propeller is 10". It's marked on the propeller. If it's 10" an 11" is 10% more, but pushing your boat faster could take significantly more than 10% more HP. So it's a bit of a guess. If you have a 10" pitch, I would probably only go up 1".

Ted

Ted, thank you and fair enough. Appreciate the advice.

 

[Nomad Willy]

I think it’s mixture/fuel related.

Surging could be caused by fuel passages having deposits in jets ect. I’m w a previous poster. Four stroke and two strokes can definitely benefit from alcohol free gas. I use fuel stabilizer also. And (at times) SeaFoam.
New outboard engines often sit for long periods of time. So fuel contamination is possible. Maybe a dealer loaned it to a friend ….?

Re the prop I’d see what you have and get a prop w less pitch. Running w lower pitch will lessen the load on the prop and many engines w various problems will run better w less load. Also a dinghy frequently to often will be required to perform w lots of stuff or people on-board so many OB’s (that are sold to go on just about any boat and load) will wind up w a bad match. Prop it (pitch) for a load most likely to be max people and gas.

Since the 20hp Suzuki is (from postings) the same basic powerhead and they share the available prop selection .. that increases the likelihood of over-propping w the smaller (15hp) engine.

 

[Jeff F]

I can hit the rev limiter with my 20 hp Tohatsu when alone and flat out in calm water. At close to 30 mph that's fast enough for me, so I take it as a signal to throttle back a bit . It was unnerving when I first encountered it shortly after breaking in the motor.

Props are always tradeoffs. I tried three different pitches on my previous RIB with an older Yamaha 15 hp. I had a higher pitched prop that would go like a banshee when light but would barely plane off with two people. The lower pitched prop was great with a load but the motor screamed at top end and it was slower when solo. In the end I settled on the stock pitch

On this dinghy I'll stick with the stock prop to preserve performance with a load.

 

[O C Diver]

I think it’s mixture/fuel related.

Surging could be caused by fuel passages having deposits in jets ect. I’m w a previous poster. Four stroke and two strokes can definitely benefit from alcohol free gas. I use fuel stabilizer also. And (at times) SeaFoam.
New outboard engines often sit for long periods of time. So fuel contamination is possible. Maybe a dealer loaned it to a friend ….?

Re the prop I’d see what you have and get a prop w less pitch. Running w lower pitch will lessen the load on the prop and many engines w various problems will run better w less load. Also a dinghy frequently to often will be required to perform w lots of stuff or people on-board so many OB’s (that are sold to go on just about any boat and load) will wind up w a bad match. Prop it (pitch) for a load most likely to be max people and gas.

Since the 20hp Suzuki is (from postings) the same basic powerhead and they share the available prop selection .. that increases the likelihood of over-propping w the smaller (15hp) engine.

Eric this is a 4 stroke electrically fuel injected engine. It's not carbureted or a two cycle. It has a computer that controls the fuel injection and has an electronic rev limiter to reduce excess RPM. There's nothing wrong with changing the propeller pitch to reducing the over reving. Flattening the pitch will only exacerbate the problem. Increasing the pitch would have an equivalent effect as adding a couple more passengers to the boat. You're increasing the load which will prevent the motor from over reving.

Ted

 

[High Wire]

So it’s been five years since this thread started. How has your Suzuki 15 hp treated you all? I’m looking at the Suzuki or tohatsu 15 hp to power a skiff here in NJ.

 

[Cigatoo]

So it’s been five years since this thread started. How has your Suzuki 15 hp treated you all? I’m looking at the Suzuki or tohatsu 15 hp to power a skiff here in NJ.

I have the Suzuki 9.9 4 stroke. EFI. Pull start. Same as the 15 and 20. Just a different control module. Very happy with it.

 

[Jc180]

My 20 hp fuel injected Suzuki was stumbling as descried. Turned out to be fuel filter.

 

[porman]

I just helped a friend change his 9.9 Suzuki to a 20 HP. All it took was a control unit and a less restrictive air intake. It gets up on plane much easier and carries a full load better.