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2003 Manual Start DF15 Hard to Start When Cold

Michael Nelson

New member
Hi

I just bought a clean used Klamath 14 footer with a 2003 Suzuki DF15 4 stroke outboard. It is *very* hard to start when the engine is cold (cold around here being 90F air temp lately). The starting procedure I have used (I have no manual) for this pull-start engine is:

1) Pump bulb until firm
2) Full choke
3) Make sure dead man clip is in place
4) Closed throttle
5) Pull, pull, pull, pull, etc.

Sometimes it will start after 10 or more pulls, but this morning in 60F temps I pulled it about 30 times without so much as a cough. Tried full choke, 1/2 choke, no choke, no throttle, a little throttle... nothing. The little red light does flash when pulling the cord, I assume that means ignition is working?

I tried replacing the two spark plugs, but the stock ones looked good, tan insulators and sharp electrode edges, slightly larger than spec gap. I pulled the cowl off and it does look like the manual choke valve is opening and closing properly. This 2003 has the Mikuni carb with manual choke, no enrichener that I can find.

When we succeed in getting the engine started cold, it idles smoothly, and runs great. Transition off idle is smooth, and it is smooth all the way up to cruise, and presents no more problems until the next cold start. Starts on first pull when it is warmed up.

I put some SeaFoam in the tank hoping for improvement, did not get any.I dumped the gas in the tank and replaced It with fresh premium, no difference.

As an experiment, I sprayed some of that ether starting spray into the intake. Started right up cold, but the idle was really really low. I let it warm up (running it on the flusher attachment) until the water coming out of the tell-tale was warm, shut it off and it restarted easily, but the idle was still real low. Hooked up a tach and it was idling around 600 RPMs. I increased it to about 900 RPMs. It is still warmed up, so it still starts easily. Found the spec for idle speed (950 to 1050 RPMs in gear) and set it to 1050.

I checked the choke valve. With the engine idling smoothly at 1050 RPMs, pulled the choke knob all the way out and RPMs dropped to a stumbly 850 RPMs, so based on a primitive test I would say the choke valve *is* richening the mixture. Not sure if it is doing it enough, but it is doing it some.

Let it sit for about an hour, and it will not start, choke or not.

Pulled the pilot jet. It appears to be completely clogged. I cannot see light through it, and compressed air did not clear it. I don't have any carb cleaner, but I did try some map sensor cleaner and that did not clear it. Now I have it in my ultrasonic cleaner running heated with a mild acidic solution to see if that will clear it. I know the hole will be tiny, but there should be a hole that you can see light through, and I cannot.

UPDATE: So... that jet is unlike any I have encountered before. The screw top is exposed to the air. It has three holes in the side and a tiny one in the bottom so I assume fuel enters the jet through the three holes and exits through the tiny one. It would not make sense for the hole to go all the way through to the outside air, so that is why I cannot see light through it. After cleaning it a couple times with ultrasound and carb cleaner and a tiny copper wire I am confident those passages are clean. Reinstalled it, same thing. Starts with starter fluid when cold (which is about 90F air temp right now) but will not start cold without the starter fluid.

I'm stumped.
 
Last edited:
Sounds fuel related,has carb been cleaned since 2003.ethanol plays havoc with fuel systems,gummed up carb possibly.pull carb and clean throughly.Fuel pump might need attention also.
 
Sounds fuel related,has carb been cleaned since 2003.ethanol plays havoc with fuel systems,gummed up carb possibly.pull carb and clean throughly.Fuel pump might need attention also.Fuel lines should be upgraded
 
Sounds fuel related,has carb been cleaned since 2003.ethanol plays havoc with fuel systems,gummed up carb possibly.pull carb and clean throughly.Fuel pump might need attention also.Fuel lines should be upgraded

Thanks. Previous owner says he disassembled and cleaned the carb and it made no difference. Gonna look at fuel pump, fuel filter and lines next I guess.
 
Ordered a fuel pump diaphragm rebuild kit. Will pick up a new fuel filter at local auto supply. The one I pulled out looks like it has been in there since the engine was built in Japan.
 
I replaced the fuel lines inside the cowl with some good Gates line and new clamps and a new filter. I think the ethanol had done a job on those old lines. I feel better about having new stuff in there anyway. The fuel filter looked like it had been in there since it was new... dark, with a lot of black stuff in it (probably debris from the ethanol eating the fuel lines. The new one is crystal clear and I can see the gas in it well.

I took the NA 12S remote control off and removed the side panel. It seems well greased, although I found a small wasp nest in there! Old one, with no wasps, but the papery chambered structure was in there. Very strange. I cleaned that out, and I don't think that had anything to do with anything. Studied the mechanism and thought I figured out how it works, but did not see anything wrong. I put it back together, and lo and behold, it works now. Not quite right... it lays flat at 9:00 position and travels up to about 11:00 position at its stop. It only works the throttle from about 10:00 to 11:00, but at least it works. There may be some adjustment in there for that, I did see some adjusters with locknuts but did not mess with them.

And now it starts with the choke when cold! Thanks guys for the help!
 
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