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Suzuki DF70 won't idle

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Mystic1

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There is a bit of history here. First it started with stalling several times at idle or shifting, but always worked when warmed up. Next it started losing power randomly and surging. Now it won't idle at all. The only code showing is a 1-5 pointing to the exhaust manifold sensor, but how could this impact the idle?It starts and runs fine with some throttle. Even running it several minutes to warm it up it will stall immediately when I throttle down to shift into gear.I cleaned the plugs and injectors. New exhaust manifold temp sensor. Replaced the IAC. New MAP sensor. New CKP sensor. This is on a 2004 engine that is spotless (never been in saltwater) and was running great last year.According to the manual only 4 inputs to the ECM control the IAC. Cylinder temp sensor (not manifold). MAP(new). CKP(new). CTPThere are no other error codes and I even bought the suzuki software and cable to diagnose the motor.If the CTP was acting up I would expect a 2-2 code.I am out of ideas and hope someone here can point me in the right direction.
 
Almost sounds like its loosing spark on a cylinder,try hooking up a timing light to the plug wires to see if its loosing spark or a cylinder drop test.Do you notice any water on the spark plugs if you remove them.
 
Thanks for the ideas.


I have an update on my engine problems. I was cranking it a couple of weeks ago when I heard a pop then a hiss for a few seconds. I suspected the head gasket went. Looking at the oil it was really dark black. Turns out there was gas in the oil. I ordered new injectors and have new spark plugs. Hopefully this will solve the problem. Also got a new fuel filter.
 
Are you doing lots of trolling? Many 4 cycle outboards will “make oil” if trolling is all the engine does. A good run at WOT will get the engine up to operating temperature and burn off the fuel in the crankcase so I’ve been told.
On the top of the VST there is a vent that directs unburnt fuel vapours into the crankcase. IF the float is too high in the VST and your doing lots of trolling then the excess fuel will be pushed out the vent into the crankcase. If your runner at a higher RPM the there is no unburnt fuel. If you can get at the vent line, follow it to where it enters into the crankcase and disconnect it. Idle the engine for 15-20 minutes and see if it starts spitting fuel.

Below is a screenshot of the exhaust manifold temperature sensor test procedure from my service manual(DF70A-90A 2009-2012). Keep in mind that if your engine is 2004, the resistance numbers given might be different.

Your second sentence “Next it started losing power randomly and surging.” is the fail safe system kicking in, a 1-5 code will limit revs to 3000rpm. I honestly think you have 2 issues, VST “making oil” and an exhaust manifold temperature sensor is pointing you towards an overheating issue or faulty sensor.

The software you purchased should give you all the engine parameters while running. What is it telling you? When was the water pump last replaced? What does the thermostat look like, freshwater engines can fill up with scale(think kettle and hard water)?
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Thanks for the great ideas. I did finally get the error code to stop by putting back the original sensor (new one was faulty I guess?). Of course with the old sensor we had no beeping and had surging issues... Well first I need to get it to idle so my injectors should be here in a day or two then I can test for fuel venting off the VST.
I don't troll at all and normally cruise above 3K rpm.


The injectors I bought (off ebay) are only about 15 bucks each. They are aftermarket of course, but the suzuki ones are the same ones used in several car engines. Ebay has many choices of new and rebuilt injectors at resonable prices, but they are not made by suzuki. Time will tell if they are good quality.
 
Hello,

I just installed new injectors, new spark plugs, and a new fuel filter. The motor started almost instantly and idled just great!!!!!!! Now for a warmer day to launch for a test run and see if the surging issue is also fixed.
 
I finally got the boat launched and the motor ran better than ever!!!! I had zero alarms, the engine ran smoothly, and I had more HP than I ever had before. Literally I never got over 25 MPH in the 5 years I owned this boat. I easily made 35 MPH yesterday! I expect my fuel consumption will go down as well.
 
Hi,

These are the ones I got, but I don't have any info on quality or how long they will last. I just know they work great at the moment.

www.ebay.com

4PCS 15710-66D00 Fuel Injectors CDH166 For Suzuki DF60-DF70 1998-2009 YU | eBay

Find many great new & used options and get the best deals for 4PCS 15710-66D00 Fuel Injectors CDH166 For Suzuki DF60-DF70 1998-2009 YU at the best online prices at eBay! Free shipping for many products!
www.ebay.com

I am sure other sellers have working injectors (new or refurbished)
 
I ordered the same injectors from another vendor, however, they are an inch shorter then the originals. Did yours fit without modification?IMG_9722.png
 
The ones I got, which look like the ones on the right in your pic were exact replacements with no mods necessary. My engine is a 2004 model so maybe yours is different? The ad says 1998 to 2009 DF 60 and 70. Does this cover your engine? There are sites to compare your engine serial number to get the year of the engine.
 
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