Suzuki DF 2.5 won't keep running

Yngmar

Yngmar

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I thought I had some understanding how these things work, but this outboard puzzles me.

It's a Suzuki 4-stroke 2.5 HP (yes, everything is really tiny) from 2008 that came with the boat and sat on the rail idly for 2-3 years, so of course the petrol had gone off. The ignition also had problems, which are sorted now after replacing the all-in-one ignition module. Spark plug is also new. So now it starts, but only runs for a couple seconds at most, often just a few turns.

So far I've rebuilt the carburetor entirely (see photo), getting all the tiny jets and nozzles out, and even taking the float and needle valve apart, soaking everything in carb cleaner. There was some gunk on the main jet and on the one with the smallest nozzle, which I think is the pilot jet, but they all cleaned up nicely and I can look through them when I hold them into this nice sunshine we've got.

I've also refreshed the petrol twice, cleaning the tank and small fuel filter inside the tank (took me a while to notice there was one). Fuel hose is good and when opening the fuel valve, plenty fuel comes out. I've put in fresh fuel and tried with both a low and a very full tank, made no difference.

The spark plug was carbing up during my many start attempts, from which I conclude there's plenty of fuel coming through? The air intake is a very simple plastic thing on the side of the carburettor with a large mesh and definitely clear.

It has a manual choke, which needs to be pulled out to start. Shoving the choke in after starting makes it die off quicker. The throttle setting during starting has the expected effect - it revs up accordingly. However, it doesn't seem to throttle up after starting. If I spray some starter spray in, it runs maybe a few seconds longer.

The fuel drain screw at the bottom of the carburetor is unfortunately seized, making it difficult to check the function of the float and needle valve, but there was plenty of fuel in the carb sump each time I took it apart after it died on me. Had it off about 4 times now and am a bit lost.

What do I check now? :dejection:

Parts diagrams are here: http://www.suzuki.com.mx/marinos/img/Catalogos/DF2.5_9900B-45245.pdf

Unfortunately a workshop manual for the 2008 model doesn't seem to be available online.

carb_cleaning.jpg
 
It is a fuel problem as you are suggesting too. You need to know for certain that there is plenty of fuel inside the carb chamber at any time. Can you unseize the fuel drain screw? can you disconnect and check that there is plenty of flow in the inlet pipe to the carburetor? Is there a fuel filter that is partly blocked? sometimes there is a small in line fuel filter just either side of the fuel cock.
 
The new generation of small four strokes have such weird fuel pathways and burn so little fuel that the smallest imperfection in any of the jets leads to problems. I had the same engine as yours, it sat for a year on the back of the boat after I got a two stroke replacement for it. When I came to sell it, I had, as you have done, to strip and clean the carb. Did it several time, each time getting a little more pedantic about how I cleaned things......

IIRC the float valve assembly is not easy to strip. But I managed to do it it the end (sorry, can't remember how!): the valve was mucky and therefore, I think, sticking. You could test to see if fuel is getting through the float valve by leaving the bowl off, connecting to the fuel pipe and seeing if fuel flows through the valve, thus getting round the problem of the stuck drain valve.
I used a needle threader, with one end of the loop pulled out, as a rod to clean the various jets.
Anyhow, after attempt four the wretched thing started and ran well, albeit a touch rough at first. You need to let it run at a fast tickover with the choke engaged for a few minutes before attempting to put the choke in and open the throttle. Fussy little engines, which SWMBO couldn't start reliably, hence it got sold!
 
I had exactly this problem and the cause was the fuel tap. Internally it has a rubber go/nogo valve which was partially blocked. I think it was a manufacturing fault but easy enough to clear. Worth a look anyway.
 
CAPTAIN FANTASTIC said:
Can you unseize the fuel drain screw?
Click to expand...

duncan99210 said:
IIRC the float valve assembly is not easy to strip. But I managed to do it it the end (sorry, can't remember how!): the valve was mucky and therefore, I think, sticking. You could test to see if fuel is getting through the float valve by leaving the bowl off, connecting to the fuel pipe and seeing if fuel flows through the valve, thus getting round the problem of the stuck drain valve.
Click to expand...

Carduelis said:
I had exactly this problem and the cause was the fuel tap.
Click to expand...

The fuel drain screw is well and truly stuck and the screw head is pretty knackered now. It probably won't cost a fortune to replace the sump and screw, but as the sump is still plenty full even when I shut the fuel cock off and then run the engine for the few seconds it runs, I don't think the problem is fuel supply into the sump, therefore I've ruled out float valve, float switch, fuel filter and fuel shut-off cock as candidates.

I did however have all of these parts apart for cleaning (the float needle valve was a bit gunked, but is shiny now, fuel filter was clean). Fuel comes out aplenty when i take the fuel hose off the carb and open the cock.

Still puzzled. :confused:
 
Tam Lin said:
Sorry to be repetitive but do what I did with mine. Replace it with a two stroke from eBay. Anyone want to buy a Suzuki which runs when it feels like it?
Click to expand...

Everyone with a 4 stroke tells me they're going to buy a 2 stroke because of all these issues.

Everyone with a 2 stroke tells me they're going to buy a 4 stroke because they hate mixing oil into their fuel.

I think first I'll get the one I have running. And I actually do like the Suzuki, apart from not working it's fairly serviceable - I've seen much worse engineering.
 
I have 2 of these, 2008 and 2015 models and I agree they can be difficult to start.

However, over the years I've developed the following method of starting them, and it works, well most of the time. But, beware you can easily flood them, and then the only way to start them, when flooded, is the close the throttle and with the choke disengage (in), keep turning it over until you cleared the fuel and then, just as you are about to give up, it'll start.

To start from cold, pull the choke out first, then gently ease the throttle open until you feel the stop, this only a fraction of a turn and you are just taking up the slack left by the action of pulling out the choke which increases the tick-over speed. This prevents the engine from stopping when you push the choke in.

Pull the cord and it should start 2nd or 3rd pull. As soon as it starts push the choke in about 1/2 way. It should run on quite a fast tickover. Give it a minute or so to warm up and then push the choke home, should continue to run at a fast tick-over, and then turn the throttle back to minimum. It should then run on a slow tick-over. Suzuki recommend that you run it on tick-over for 5 minutes before putting it on load.

Both my Suzuki DF 2.5 will reliably start using this method, even after a winter sitting doing nothing in the garage, I've never had to refresh the fuel, but I do run them dry when I flush them with fresh water and change the oil, before putting them away for the winter.

I'd also add that both engines have been well and truly dunked, several times, when the inflatable dinghy has flipped, in strong winds, when tied to the stern of the boat at anchor. My experience suggest that they withstand a reasonable amount of abuse and they are very powerful for their size, one up they'll plane my 2.7m inflatable at 11 knots.

As a final though, I have full service manual for the DF2.5, dated May 2006 as a .pdf.
The file 27,234KB and I'm happy to email it to you if it would be useful, just PM me an email address.
 
Last edited:
Ian_Edwards said:
I have 2 of these, 2008 and 2015 models and I agree they can be difficult to start.

However, over the years I've developed the following method of starting them, and it works, well most of the time. But, beware you can easily flood them, and then the only way to start them, when flooded, is the close the throttle and with the choke disengage (in), keep turning it over until you cleared the fuel and then, just as you are about to give up, it'll start.

To start from cold, pull the choke out first, then gently ease the throttle open until you feel the stop, this only a fraction of a turn and you are just taking up the slack left by the action of pulling out the choke which increases the tick-over speed. This prevents the engine from stopping when you push the choke in.

Pull the cord and it should start 2nd or 3rd pull. As soon as it starts push the choke in about 1/2 way. It should run on quite a fast tickover. Give it a minute or so to warm up and then push the choke home, should continue to run at a fast tick-over, and then turn the throttle back to minimum. It should then run on a slow tick-over. Suzuki recommend that you run it on tick-over for 5 minutes before putting it on load.

Both my Suzuki DF 2.5 will reliably start using this method, even after a winter sitting doing nothing in the garage, I've never had to refresh the fuel, but I do run them dry when I flush them with fresh water and change the oil, before putting them away for the winter.

I'd also add that both engines have been well and truly dunked, several times, when the inflatable dinghy has flipped, in strong winds, when tied to the stern of the boat at anchor. My experience suggest that they withstand a reasonable amount of abuse and they are very powerful for their size, one up they'll plane my 2.7m inflatable at 11 knots.

As a final though, I have full service manual for the DF2.5, dated May 2006 as a .pdf.
The file 27,234KB and I'm happy to email it to you if it would be useful, just PM me an email address.
Click to expand...

I've tried all of the above, except I haven't tried dunking it yet! ;-)

The PDF would be most welcome - would you mind uploading it to https://pdf.yt/ and sharing the resulting link here? If not, I'll PM you an email address, but this may be easier and useful to other forumites.
 
I tried https://pdf.yt/ but got his message!

"Uploads are disabled for a few more days as the work on a new CDN is finalized. More information can be found in this blog post.

You can still upload documents by e-mail! Send your documents to pdfy-upload@cryto.net - they are processed roughly once a day."

If you need the document urgently, PM me.

I'll try the email approach, never used it before, do I just attach the .pdf to an email, or do I need to add a title, or what?

Will I still get a link I can post on the forum?
 
Problem on mine was the pilot and main jets. The thing wouldnt idle, and when run at more than 1/3rd power would die. We ended up using a small amount of choke to keep it going until I could strip and clean the carb. Runs sweetly now, but appears to gunk up very easily. Florists wire or heavy fishing line does a good job of cleaning the jets.
 
Yngmar said:
The fuel drain screw is well and truly stuck and the screw head is pretty knackered now. It probably won't cost a fortune to replace the sump and screw, but as the sump is still plenty full even when I shut the fuel cock off and then run the engine for the few seconds it runs, I don't think the problem is fuel supply into the sump, therefore I've ruled out float valve, float switch, fuel filter and fuel shut-off cock as candidates.

I did however have all of these parts apart for cleaning (the float needle valve was a bit gunked, but is shiny now, fuel filter was clean). Fuel comes out aplenty when i take the fuel hose off the carb and open the cock.

Still puzzled. :confused:
Click to expand...

If fuel is not the problem, then it can only be the ignition; can you connect a strobe light between spark plug and spark plug lead to visually see that there is spark all the time. I still believe the problem is with the fuel rather than ignition.
It is worrying because I am planning to buy a Suzuki 2.5 in the next few weeks.
 
I've just got it running. After reading the linked thread and the Suzukioutboardforum thread linked from there, I scraped together enough motivation to take the carburetor apart for a 5th time (or 6th? I lost count). Again taking all the nozzles out and cleaning them, even though they looked nice and clean already. I again sprayed carb cleaner into every hole, then soaked it down in some more, and this time started it with the carburetor full of carb cleaner (desperate measures - the stuff is nice and flammable). It started on the 2nd pull, sputtered and nearly died again, but then recovered and kept running. Starts and runs fine since!

So it probably was dirt somewhere in the inaccessible areas of the carburetor that was wandering around in there and clogging things after reassembly, then hiding again upon disassembly (sneaky dirt :mad-new:). The half can of carb cleaner must've finally dissolved it enough to be pulled through, or perhaps the flammability of it helped the engine run long enough to suck the gunk through.

To be fair to Suzuki, it was stored with a full fuel tank and carb sump hanging on the pushpit for what must've been years while in the brokerage berth, the fuel smelled all kinds of funky and had water and a dead moth in it. There was lots of yellow crud from bad fuel in the carb the first time I stripped it. I shall buy some fuel stabilizer to add for the future to prevent this and run the sump dry before storing (drain screw absolutely knackered now).

Now I'm going to check/change the impeller, which I hadn't bothered before and then go for a test ride! :)

Thanks for all the advice. Ian_Edwards, you've got a PM.
 
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Had one of those with a similar problem. Only answer in the end was to slowly increase the "Slow Running" setting until it stopped cutting out.
 
Yngmar said:
Now I'm going to check/change the impeller, which I hadn't bothered before and then go for a test ride! :)
Click to expand...

The impeller change is not nice on this engine. It starts with removing the power head.

I then relaunched the tender for a test drive up and down the marina and on the way back the outboard started overheating and losing power, so I shut it off and rowed back. More work ahead it seems!

Thanks to Ian_Edwards I now have the workshop manual, which is like someone turning on the lights after you've spent hours trying to build a Jenga tower in absolute darkness. Nigel has kindly made it available on the Bavaria forums download section: http://www.bavariayacht.info/downloads.htm
 
Next time us a sonic cleaning bath.Strip and give it at least 20 minutes.Some of the galleries are so small that carb cleaner and an air line wont shift the crud.Works every time
 
Hi Ian

I recently purchased a 2016 Suzuki DF 2.5 'blind' on Gumtree. It stared first pull :) and then stopped :(. I followed your advice for the starting procedure and bingo - no problems since.

Do you still have a soft copy of the services manual that you could post or email? The links that I have found mentioned on other threads no longer seem to work.

James
 
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