suziki engine missing starting at 3000 rpm

[rpdixon13]

Suzuki df50 4 stroke electronic fuel injection.at about 3000 rpm
Motor begins to sputtter. Quits when you bring the rpm down again.
New plugs have been installed. Problem did not go away.
What would be the next step to solve this problem?

[Kari Vainola]

Take the kill swicth key away, turn the ignition lock key to ign.on and pull the killswitch three times under 10 seconds and you hear a beep. Done. Put the key back and start your engine. This procedure is detailed in your owners manual.

[Moonlighter]

Kari, what you have described is the procedure to reset the oil change service reminder alert. It has nothing to do with an engine that is misfiring or spluttering once it reaches 3000rpm!

Dixon - suggest you give us a bit more info so people can offer help..

For example, is the fuel primer bulb still firm when the engine does this? If not, It could be a fuel blockage or air leak that is starving the engine for fuel once it gets to higher revs?

If it seems to be starving for fuel, first suggestion would be to change your fuel filter (you ARE using a RACOR style of fuel filter with water separator aren't you? These are essential for modern 4 stroke engines.

Also, check fuel lines and make sure there are no kinks or leaks at joins.

Any more description of exactly what the engine is doing, and how it sounds, would be useful.

[Kari Vainola]

Moonlighter: it helped me several times with my nmea2K problem, when my DF140 dropped rpm to 3000. After engine shutdown, i reseted this oil change reminder procedure and restarted the engine. Now it is working okay. Wondering how this is possible if this resetting is only made for oil change reminder?

[Elliot Griffin]

1999 DF50 won't go over 3000 rpm on water, but will on garden hose

I'd really like to know the root cause and/or solution to the 2013 post. I have a 1999 DF50 which won't go over 3000 rpm on water, but will on garden hose. The bulb begins to soften over 2000 rpm. I changed the external separator filter, changed the low pressure and high pressure filters. I drained the vst and fuel looked okay. There were one or two tiny black specs which came out of the vst, and I can see a couple tiny black specs inside the high pressure filter. No warning lights or beeps during any operation. Battery voltage is fine. I don't have any kinks in the fuel hose. Fuel hose and bulb are new, but tank is original ~2000. Fuel connector to engine is original Suzuki make. My engine is 1999 but with less than 300 hours, it had some long periods of time with old gas in engine. In past I used gas with ethanol and added Stabil. I recently switched to ethanol free. I haven't done the fuel pressure test because it idles/trolls fine, and manual section 5-5 specifies checking pressure at idle. I tried the fuel leak check per service manual (turning key to on 3 times, visual leak check). I'm thinking as a sanity check, I should check supply voltage to high pressure pump with key on. After that I guess the next step is either to get a new tank, or to inspect inside the VST. Would really appreciate some suggestions. I feel like I'm just changing parts without any clue how to diagnose this. I don't have a scan tool, didn't get any warnings, so don't know if that will help or not, saw one on ebay for ~$100. Most of the past issues I had with this engine were overheating warnings, clogged pee lines, seized thermostat. I replaced the voltage regulator once because the original one got burned up due to battery issue. Other than that, it's just been regular maintenance items that I've worked on.

[Solarman]

A neutral safety switch problem could limit motor to 3k rpms.

Good luck.