Suzuki DF20 ATS - is this likely to be the impeller?

[TwoHooter]

Short story: I set up a correct sized tank of fresh water to flush, started engine, no pee. Fitted a mains supply hose to the flushing port and the pee is a syrong jet of water. Is a failed impeller the most likely explanation?

Long story: The reason for setting up the flush is that our second hand DF20 (2018, low hours) has had a fortune spent on it and the principal problem has never been solved. It runs fine at slow speeds. At high power settings it runs beautifully for a while then the power dies. The engine used to stop completely but after having a new fuel system fitted from tank through Suzuki filter, all new lines, new fuel pump, it just loses power, it doesn't stop. It's also had other things done which I'd have to look up. A friend had the same problem and in his words: 'The thermostat has a ’notch’ which masquerades as a small bypass to circulate a minute amount of water. I told the engineer to drill a 1/8” hole alongside - seems to have worked ! The hole is in the circular plate blocking the passage of water until the valve opens at normaI operating temperature'.

I was planning to flush the system thoroughly in the tank then repeat the same hole-drilling trick but with no pee I'm wondering if I should try and change the impeller first. The Suzuki is on the Brig tender to our motorboat, I have no trailer or even a ball hitch on our car, so I have to do all work in the open on the boat deck, and I've never done any work on modern engines before, which doesn't help.

[Pikey Dave]

In my experience, Suzukis aren’t great running in buckets/tubs. They need to be well immersed with the water well up the leg.

[TwoHooter]

The tub contained water as far up the leg as the plate identified by a red arrow in the second photo.
Extra info: I first tried flushing with a shallower tub of water. I noticed the usual disturbance in the water which you get when the engine is running (but prop not engaged). No pee. I looked on Youtube and saw that most people have a deeper tub of flushing water so I bought a dustbin and cut the top off, I'm sure it's deep enough. But then when I did another test there was no disturbance in the water which I think might be another indication that the impeller has failed.
NB: I have run the engine only for a few seconds each time, perhaps 20 seconds. No red light and no smell of overheating so I'm hopeful I haven't damaged it.

First photo
https://www.flickr.com/photos/119194913@N05/53754860519

Second photo
https://www.flickr.com/photos/119194913@N05/53754950025

[Pikey Dave]

You’re probably not giving it enough time to get water around the passages tbh. I’d increase the depth in the bucket to as deep as possible & give it at least a minute. The impeller will be immersed anyway, so will be running in water.

[Nasher]

I'd agree that you may need to run it for longer, some engines don't 'pee' until after the Thermostat has opened anyway, because the outlet is after the Thermostat in the system.

Run it for a bit longer, if you are worried you can run it up with the hose attached as well as it being in the bin, then disconnect the hose after a while.

[Fenlander]

I know PD has always felt the DF20A needed a good depth of water but mine was much better as the image below shows. It only needed water above the AV plate to show well at the tell tale.

Having said that I always felt after not being used for a while (as in many weeks) the tell tale was slow to appear... so much so when it was brand new the first couple of starts I turned it off soon after starting when I wondered if there was a problem with the slow appearance of the tell tale.

As Nasher mentions I've experienced an erratic tell tale on Mercury/Mariners where they would be affected by thermostat opening at idle/slow speeds (characteristic not a fault). The Suzuki though should be a constant strong stream.

[Steve509926]

Originally Posted by TwoHooter

It runs fine at slow speeds. At high power settings it runs beautifully for a while then the power dies

When it was running beautifully, did you notice a strong tell tail. When the power died did you notice a red flashing warning light, did the OB go into limp home mode.

Sounds similar to Brinormeg's problem, take a look at this thread:-

https://www.rib.net/forum/f36/most-expensive-3-minutes-of-pleasure-in-my-life-87983-5.html

Posts #83 - #87

[Brinormeg]

If still not peeing after leaving it longer as the the guys say, it might be worth picking up the diagnostic cables and software off eBay to check for overheating or other issues.

Steve’s right in that there should be a light comes on if the OB is detecting a potential overheat and it will cut power to below certain levels but will still run.

Like PD I also found my Suzuki needed to be in a deeper bucket than most, but ran fine filling up to same level as your pic.

As you will see in Steve’s link, my impeller and housing were completely mushed, so definitely be worth a look if all else fails and relatively easy to do if you check out a few posts on here and youtube.
Although I would expect to see the light come on.

[jeffstevens763@g]

Not too familiar with the 20 but if the impeller hasn’t been changed since new it will be hard and not pump very well second is it in limp mode because of that my 25 has warning lights does the 20?

[Fenlander]

Yes they have the light Jeff and you can get blink codes of faults if you don't have the full laptop diagnostics.

[jeffstevens763@g]

Originally Posted by Fenlander

Yes they have the light Jeff and you can get blink codes of faults if you don't have the full laptop diagnostics.

So does it throw a code up and limp if say the intake gets blocked David

[Fenlander]

Yes it will bring the red light on for over revs, low oil pressure or overheat.... also holding to limp speed.

Blink codes are in the workshop manual section 1A-12.... but they only help diagnose the engine sensors for faults,

[smallribber]

Not your particular outboard but these 2 videos might help

https://www.youtube.com/watch?v=iTxzUcsPmFI

https://www.youtube.com/watch?v=OFbP0GJGOb8

[smallribber]

Those Suzukis can also suffer from corroded and broken water delivery pipe at the power head.

Remember however that the tell tale is just that the exit from the water jacket for the tell tail is at the bottom and can block up even thought the main coolant water is pumping just fine.

Try the blowing ain’t up the telltale pipe this offten clears it untill it blocks again

[TwoHooter]

Thanks everyone, I really appreciate your comments. Long reply but I don't want to miss anyone out.

@PD, @Nasher, @Fenlander – It's possible I'm being too quick. The lack of pee has made me shut the engine down very soon. Thinking about it further, if there's no red light and no smell of overheating I should be OK to run it a bit longer. OTOH engines can seize very quickly sometimes, we had a JCB Telehandler go from perfect working order and full service history to a completely trashed engine in about 30 seconds recently (or so the driver says). Then again, I'm so sick of this engine I'd almost like the brugger to seize so I can get rid of it with a clear conscience and start again with something else.

@Nasher – I don't think I'll run it in the tub with the hose connected because as I said the pee is OK under mains pressure (it squirts from the boat deck right across the pontoon, several metres) – so if I connect the hose I won't know whether the system is working properly.

@Fenlander – I haven't forgotten your kindness in sharing the manuals even though I haven't used them yet. I will now because I've spent £1,200 on “experts” who haven't solved the underlying problem of power loss at high revs. I was amused to see your bucket, that is the exact same thing I bought to try the bucket test and then I decided I needed a bigger bucket so I bought the dustbin.

@Steve509926 – There's always been a tell tale until now on test in the bucket – I'd say pretty strong, but not as strong as under mains pressure from the hose.

@Steve, @Brinormeg - I read the link. Awful. And that was a brand new motor. I read on a bit further to where the engineers put the motor in the car the wrong way and it leaked oil – I've just about had it with outboard engineers myself. I've got a really good engineer who helps me with the big boat (single John Deere 6 cylinder tractor engine, very old, no ECU) but so far the outboard guys don't impress me.

@Brinormeg – The long term power loss problem is just like what you would expect if it was going into limp mode, but no red light, which I find weird. Yes I'll buy the diagnostic stuff.

@Jeffstevens, @Fenlander – The impeller was changed in May last year. But it hasn't been used regularly. Yes I have a red warning light (and buzzer) – they have never come on except in pre-start so I don't have any blink codes.

@Eassedalenovice – thanks for the videos, I've already watched those! I assume the tell tale can't be blocked because the hose connected to the flushing port produces a strong jet.

In the next post I am putting a link to my invoices and my complete log since May 2023

[TwoHooter]

Invoices here: https://www.flickr.com/photos/119194...77720317389352

Log since Service in May 2023:-
11/05/23 Collected tender from Plymouth Marine Centre 1 hour after high water. While driving at restricted speed down Cattewater engine became sluggish, unresponsive to throttle increases, then stopped. Tell-tale water jet normal, no smell of overheating. Went into the Sound and opened up to planing speed- all seemed OK. On lifting back onto boat deck discovered bilge bung not replaced, bilge full of water.
25/05/23 Launched tender and went ashore for walk in woods. Outboard behaved OK. Beautiful weather.
26/05/23 Went ashore by tender..... Outboard lost some power approaching Harbourmaster's pontoon. No warning light or buzzer.
29/05/23 Departed in tender for proposed visit to St. Germans/Linyher Rivers – tender engine surged and lost power several times, turned back after Lido. Changed fuel tanks to new fuel purchased today, did a test run solo – seemed better then same symptoms, returned. No warning light or buzzer.
30/05/23 Went out for test - the engine ran well for about a minute, you wouldn't think anything was wrong, it sounded OK and produced enough power to run on the plane without needing full throttle, then it lost almost all power. Checked fuel line and tried again with exactly the same result. Limped back to Sutton Harbour. While waiting for the lock the engine stopped and would not re-start, I had to be towed back in. Stripped both tanks, checked the dip tubes and filters, blew through vents - there is nothing wrong with tanks. The hose from the tanks with bulb and inline fuel filter were new this year. I opened the vent on the quick-fit fuel line connection to the engine and pressed the bulb - fuel is getting through. I think the problem must be on the engine itself.
01/06/23 Took tender to Plymouth Marine Centre. Changed fuel pump. Tried it again in the Sound – no improvement. Ordered Crewsaver Inflatable tender.
22/6/23 Drove tender to Lewis Marine at Yacht Haven Quay on the Cattewater. Fault diagnosed as blocked injector. Cleaned and refitted, new fuel line and water trap fitted. Collected the tender and drove the length of the Hoe in choppy water to Mount Edgombe. In calm water opened up to fast planing speed, briefly to full power. Drove back to Sutton Harbour. Motor performed satisfactorily throughout.
13/04/24 Launched tender. Started easily, just 4 No. tries, 3 seconds turning over each try, then ran smoothly. Test drive within marina, all OK.
14/04/24 Launched & started tender easily. Drove out into the Sound. Performed perfectly for about 5 minutes, about 75% power in choppy sea. Then the power fell away, just like previously, but the engine did not stop. Drove up the Cattewater - all OK at about 6 knots (legal limit). Engine then lost power but turned out to (probably) be an almost empty tank. Refilled with 5L Aspen synthetic fuel. Engine then ran OK back down the Cattewater at similar speed, then out into the sound at slightly higher speed – very choppy swell possibly accentuated by passing trip catamaran. At one point the hull fell hard between two wave peaks. Power then fell away again but this may have been the throttle moving because of the impact. Drove some further distance – all seemed OK but on final approach to Fishers Nose the engine picked up suggesting it had been running below the speed the throttle was commanding. Total excursion nearly 90 minutes. Engine did not stop at any time except when turned off to refuel. Conclusion is that the tender is safe for use in sheltered waters not at risk of strong currents but further diagnosis and rectification is needed. Retrieved tender.
28/05/24 Decided to flush Suzuki outboard motor by running in fresh water on boat deck, first with a “Trug” tub of water. Noticed the usual disturbance in the water which you get when the engine is running (but prop not engaged). No “pee” from tell-tale. Looked on Youtube and saw that most people have a deeper tub of flushing water so bought a dustbin and cut the top off, 18 inches deep, motor immersed up leg to top “plate”. Ran again and noticed there was no disturbance in the water. Connected mains supply hose to flushing port and got a very strong jet of water from the tell-tale.
NB: Ran the engine only for a very short time perhaps 20 seconds each time. No red light and no smell of overheating so hopeful I haven't damaged it.
29/05/24 Posted on Ribnet forum.

[Peter_C]

I am a firm believer in visually inspecting the impellar at any sign of a possible issue or anytime it is in question, no matter if it was replaced 5 hours ago. It is only 5-7 bolts and takes less than 5 minutes to pull the lower leg once you have done it before. A few more bolts and you can see what is going on. Impellars fail often and can cause engine damage quickly if overheated.

To make sure I never have down time I always keep a spare impellar at home. They are quick to change, but impossible to get a hold of on a Friday evening.

[TwoHooter]

Originally Posted by Peter_C

I am a firm believer in visually inspecting the impellar at any sign of a possible issue or anytime it is in question, no matter if it was replaced 5 hours ago. It is only 5-7 bolts and takes less than 5 minutes to pull the lower leg once you have done it before. A few more bolts and you can see what is going on. Impellars fail often and can cause engine damage quickly if overheated. To make sure I never have down time I always keep a spare impellar at home. They are quick to change, but impossible to get a hold of on a Friday evening.

Yes, I think you are right. I need to learn how to do this anyway.

Can someone tell me how high the bottom of this Suzuki DF20 outboard has to be above the floor so that the lower leg can be pulled? I can lift the RIB as high as I like on the derrick but it will then swing around even if I lash it - I have some trestles and I'm hoping if I put the RIB on those (with the derrick taking 50% of the weight) it will be high enough to do the job.

[TwoHooter]

Answered my own question. In Fenlander's DIY service thread (https://www.rib.net/forum/f36/suzuki...ice-75209.html) he mentioned tilting the motor to get the leg off so the trestles will definitely be tall enough.

[Steve509926]

Apologies in advance for the thread drift. Whilst I was watching Easdalenovice's excellent video about Rydlym (you never know I may need to use it one day), I couldn't help but notice the spark plugs.
I'd be very careful if I was you Dennis when you come to do your annual service/maintenance. I think they have corroded so much that there's a possibility they could snap, they obviously don't make them like they use to.