Suzuki DF 2.5 won't keep running

They’re lovely little engines while they’re working and horrible little engines for the fuel-gunking reasons given above. I last had to strip the carb of my DF2.5 in the summer. Use a ‘hair’ from a brass brush to clean the nozzles and an air blower can. The problem you describe is certainly fuel-related.

Once done, clean tank etc with fresh fuel and leave to dry; dispose of all old fuel and start with fresh fuel.

When you leave the engine, first run it with the fuel tap turned off until dry. You need that carb empty before storage. This, I have repeatedly learned, is critical, critical, critical. Shouldn’t be - arguably makes the engine unfit for purpose - but sadly is.

EDIT - And empty the fuel tank from time to time - oh, and don’t forget to empty, clean, dry and refill your jerry can at least once a season. When you keep topping it up, imagine all the seasons-old fuel that’s absorbed water and decomposed that’s sitting in there, only to be mixed by you in the Jerry can and introduced straight back into your lovely clean carb.
 
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Once you have got it running in my experience the way to minimise further problems is to use the premium fuels such as shell vpower. The cleaning additives have certainly kept my little old 2hp 4 stroke Honda running sweetly for a few years and it used to have all the above problems before I put a new carb in. Incidentally importing the carb from America was significantly cheaper than driving 3 mile down the road to the local dealer.
 
It's really interesting to hear different people cope with small 4 stroke engines, as I've said in earlier I have two DF2.5's both these engines have been immersed in seawater, when the dinghy flipped, both recovered 100% after washing down with fresh water, changing the engine oil, stripping and cleaning the carb' and jets, and putting new petrol in the tank. I also sprayed them with AFC 50.

I don't discard the fuel at the end of the season, I was using 2 year old fuel in August this year, no problem.

However, at the end of each season, I do run them in fresh water, run the carb dry, ie turn the fuel off and run at high revs until they stop, then empty the carb' bow. I also change the engine and gearbox oil every year, grease everything that moves, and spray the head with AFC 50, including the return spring in the recoil start. I also store them in the garage over winter.

In general I don't have a problem starting them, although my partner does, but she is only 5ft tall and weighs in at less than 8 stone, so she may have a problem pulling the recoil start far enough and fast enough.

The biggest problem I have is the recoils start kicking back when I try and start them, I've had sore knuckles several times when the the rubber T on the end of the starter rope has kicked back.

So from my point of view I think that they are good little engines .... but other may have a different view.
 
Alex_Blackwood said:
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.
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If you mean the tick over adjusting screw on the venturi spindle DO NOT INCREASE IT THE REVS TO OVERCOME IDLING ISSUES.
What happens is is the engine idles too fast and wrecks the clutch dog and pinion. Even on a newish engine the cost of repair would probably write it off.
Had loads of experiences with these and this problem. If it doesnt idle clean the carb or pay for someone to do it.
 
Hi Ian

Many thanks. Much appreciated. Do you know if there were any significant changes to the engine post 2011? It looks like they changed the size of the main and pilot carb jets from engine number 41001.

James

James
 
James_C said:
Do you know if there were any significant changes to the engine post 2011? It looks like they changed the size of the main and pilot carb jets from engine number 41001.
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I don't know about the date and model number of the change, but that is apparently the change to make if you want to alleviate (but not remove) this problem with this engine. I posted some details of the jet changes on an earlier thread about the DF2.5 here: http://www.ybw.com/forums/showthread.php?314023-Suzuki-DF-2-5-running-issues&p=5888030#post5888030. The changes proposed were to increase the Pilot Jet from #32 to #34 and the Main Jet from #64 to #66. In fact you could order the following parts (just Google them):

  • 09491-66005 = Main Jet #66
  • 09492-34004 = Pilot Jet #34
  • (if necessary) 13236-97J20 = Main Nozzle

But this replacement does not override the advice here to run the engine dry before storing it and to change the fuel (including in your jerry can!) every now and again. If you don't do that, you will still get problems with this engine (and doubtless with others with similarly minute apertures when used with degrading fuel).
 
The tick over jet was the problem on mine. This is the jet below the stainless screw inside the upper air balance chamber.
The fuel comes up through the jet and into the drilled port above the brass jet, from there to the single smallest hole after the throttle butterfly. the problem is that this drilled port has an elbow making it difficult to clean
Solution was carb cleaner with insulating tape on the nozzle pipe to plug the removed stainless screw, squirt down here until it comes out the small hole (do this with jet in place).

Another problem mentioned was kick back. Solution is to gently pull starter cord until pawls engage, keep gently pulling until compression is felt, release cord back to home position, pull gently until pawls are felt to engage, then pull start from there. This way the engine is pulled to start with it at TDC. this will also stop the kick back and not rip out the pawls
 
colind3782 said:
I would be interested in the link too if you wouldn't mind.
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I have recently registered dealing with a DF 2.5 that suddenly after good years won’t idle. I too would be grateful for access to a service manual before tearing the carb apart.

Thanks so much in advance!
 
Similar symptoms to mine. Starts, runs a few seconds, longer if you play with the choke, won't accelerate and dies if you try. If you accelerate and pull more choke does it speed up a bit in response to the choke? My guess is that it will. If so it's running on the choke/slow running jeyt only and not the main jet.

Likely to be a blockage/restriction in the main jet or passages to it. Cleaning all those passages of all the varnish and crud is essential and the tiniest loose particle can/will block the jet. An airline is, imo, virtually essential for blowing the passages through. Finding something preferably non metallic of exactly the right size to riddle out those tiny holes is not easy but worthwhile.
Flush the tank thoroughly. Remove, roll between your fingers and flush all fuel lines. You need to be as scrupulously careful to clean these as you evidently are with your carb dismantling. :)Then fit a small inline fuel filter. Ensure the air vent valve on the filler cap does actually vent when opened.

If the engine is to be left for more than a month or so turn the fuel valve off and run the carb dry. If left over winter empty the tank too. Modern petrol is horrible stuff for gumming up when left standing.
 
I used the exploded parts diagram here to help me do it to mine with exactly the same problem.

https://www.maritimepropulsion.com/files/pdf/1001467

Don’t forget to clean out and dry the tank too. And the Jerry can from which you’re filling it, after ditching its contents. It’s all tainted.

With respect to Old Bumbulum, I’d got myself a small inline fuel filter to insert in the fuel pipe too, but I have been told by more than one mechanic who should know, that it won’t solve the problem for you: it’d get rid of particulates, sure, but your problem is the degradation of the fuel and corrosion inside the carb caused by water which the fuel absorbs because ethanol, used nowadays in petrol, is hydroscopic: it absorbs water - and water condenses from air in the tank when it cools. An in-line paper filter can’t help you with this. But religious use of one of these will, combined with draining the carb/ at least running it dry, before leaving it for more than a few days.

https://www.amazon.co.uk/Mr-Funnel-Portable-Fuel-Filter/dp/B01N1T3LW6

I aso now use a petrol fuel additive when I fill the Jerry can to slow the degradation of the fuel, but I am not a chemist and don’t know how effective this is.
 
BelleSerene said:
I used the exploded parts diagram here to help me do it to mine with exactly the same problem.

https://www.maritimepropulsion.com/files/pdf/1001467

Don’t forget to clean out and dry the tank too. And the Jerry can from which you’re filling it, after ditching its contents. It’s all tainted.

With respect to Old Bumbulum, I’d got myself a small inline fuel filter to insert in the fuel pipe too, but I have been told by more than one mechanic who should know, that it won’t solve the problem for you: it’d get rid of particulates, sure, but your problem is the degradation of the fuel and corrosion inside the carb caused by water which the fuel absorbs because ethanol, used nowadays in petrol, is hydroscopic: it absorbs water - and water condenses from air in the tank when it cools. An in-line paper filter can’t help you with this. But religious use of one of these will, combined with draining the carb/ at least running it dry, before leaving it for more than a few days.

https://www.amazon.co.uk/Mr-Funnel-Portable-Fuel-Filter/dp/B01N1T3LW6

I aso now use a petrol fuel additive when I fill the Jerry can to slow the degradation of the fuel, but I am not a chemist and don’t know how effective this is.
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We returned to our boat a couple of days ago after the Suzuki DF2.5 had spent another 2 months idle in the hot Med sun. I filled the tank with the dregs of the 4 year old petrol that I'm gradually using up. I pulled out the choke, gently pulled the cord.... And she burst into life before the cord was even fully extended.

She is a first pull starter every time, every year, any old petrol.

There are only two secrets: fit a small inline fuel filter for 50p and drain the carb using the fuel drain under the float bowl every time you leave the motor for more than a couple of weeks.

Richard
 
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I can get mine to run without choke after several minutes, but as soon as the throttle gets down to a slow speed (the notch mark) it stalls. Can only restart with choke again, which I read is not uncommon.

I’ve always closed the fuel switch and let the engine burn through fuel in the carb, but now it seems to be blocked somewhere. I’ve also recently started to only buy fuel without ethanol as I’ve heard how bad that is.

Am really hoping to find a copy of the service manual others have referenced so I can get this back to normal.
 
RobMilne said:
I can get mine to run without choke after several minutes, but as soon as the throttle gets down to a slow speed (the notch mark) it stalls. Can only restart with choke again, which I read is not uncommon.

I’ve always closed the fuel switch and let the engine burn through fuel in the carb, but now it seems to be blocked somewhere. I’ve also recently started to only buy fuel without ethanol as I’ve heard how bad that is.

Am really hoping to find a copy of the service manual others have referenced so I can get this back to normal.
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Allow the engine to run through to stall does not clear the float bowl I'm afraid. In fact, some argue that it makes things worse if you're leaving the engine for a short time as there is less petrol to evaporate. The Suzuki has a simple drain valve under the bowl and that is 100% effective and, as a side effect, flushes out any grit which would eventually block the tiny jets. :)

Richard
 
BelleSerene said:
your problem is the degradation of the fuel and corrosion inside the carb caused by water which the fuel absorbs because ethanol, used nowadays in petrol, is hydroscopic: it absorbs water - and water condenses from air in the tank when it cools.
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I think this is only half the story. Using fresh fuel goes without saying, I had't reasalised it was even necessary to say so!
Stale fuel has lost the volatile aromatic components that intiate the burn, hence poor starting with stale fuel. Your nose will tell you; fresh fuel stngs the eyes and nose, stale fuel just smells a bit "petroly". If a sniff doesn't make eyes and nose flinch and smart ditch it.
Water attracted into the fuel is a different problem that can cause corrosion making needle valves stick and furring up orifices. At least this green, furry stuff is visible.
The other problem is the way modern petrol seems to deposit varnish or gum when it dries out. This clogs jets, orifices and passageways and is not easily seen, dislodged or dissolved even with acetone. My carb had the float still firmly glued to the bottom of the float chamber even after 5 days with fresh fuel in it causing the carb to spew fuel from the overflow. Petrol scarcely shifted it even with a stiff brush.
A filter is essential after you've cleaned the tank and lines to keep the carb's jets clear of debris which so easily affects these small engines.
 
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