DF150 Stalling when shifting into neutral

[Jim Rufiange]

A beautiful February Saturday and we were able to take our boat out for the first time this year. Boat is a 2017 Stingray 192SC with a DF150. Was purchased new in Feb 2017. Had our 20 hr service last August. Went out a few times after that in 2017. (Did notice venting sound when removing gas cap in late 2017 which hadn't happened before. Also experienced difficulty fueling. Attributed it to extreme heat at the time.)

Ran engine Saturday morning at the house for 5 minutes and checked everything out. Was fine (fluid levels, etc). Went to lake, warmed engine at ramp, launched, headed to courtesy dock and engine began stalling every time I would shift from fwd to neutral. I had difficulty again fueling beforehand so I thought it could be a venting issue. Removed gas cap thinking it could help if it was a venting issue but it did not. Did not lose power to any gauges or accessories.

Engine ran great on the water. Started fine each time it stalled. After anchoring for a bit, started fine, returned to dock and had same issue. It's a harrowing experience only operating a boat for a year and losing power around the dock and other boats.

Any thoughts on whether this is an engine, electrical, or fueling issue? Please let me know if more info would help. Thank you in advance.

[redlowrey]

Before everybody tells you to replace the iac valve do these couple of things, some times if you haven't started the engine for a while,and when you crank it over the battery voltage will drop below 9 volts, Suzuki have not got built in software to cater for it, and you can get some weird things happening from your electronics. Disconnect the batteries and put them on charge for a day and when you start the engine use both batteries.

What should happen, when you move the shift leaver into neutral, the ecu will bypass more air and advance the timing to prevent stalling from information from the throttle position switch, shift position leaver sensor, and neutral switch, if they get out of the voltage scale they work in, the check engine light will come on and by the sounds of it that's not happening. The six wire Mitsubishi iac valve on these engines are usually very reliable. If the problem is still there after doing that I will show you how to test the valve.

[Greg Moore]

You can test the IAC with a common ohm meter, it's just 2 wires and has a plug near front of motor. Do not continue to use the boat until you test it! It can stick (very unlikely that new) or go open or shorted. Mine on a DF140a went short circuit. Same symptoms, stalled sometimes on shift, more commonly after dropping from full throttle to idle. In my case it was shorted and I didn't check it. Ended up burning up my ECU as it was being overloaded driving into a shorted coil and overheated. Expensive (but easy) fix for me.

[Moonlighter]

Its still under warranty - talk to your dealer and ask them to fix it. Thats their role.

Get someone to take a mobile phone video of it when the porblem is happening. Show the dealer the video evidence. Also tell them about the fuelling issues. (Check that there is no obstruction in the breather line).

[redlowrey]

You can test the IAC with a common ohm meter, it's just 2 wires and has a plug near front of motor. Do not continue to use the boat until you test it! It can stick (very unlikely that new) or go open or shorted. Mine on a DF140a went short circuit. Same symptoms, stalled sometimes on shift, more commonly after dropping from full throttle to idle. In my case it was shorted and I didn't check it. Ended up burning up my ECU as it was being overloaded driving into a shorted coil and overheated. Expensive (but easy) fix for me.

''''''''''''''''''mate totally different iac valves, yours is a two wire magnetic plunger type, df150 175 run a six wire mitubishi type stepper motor same as the cars.

[Greg Moore]

I stand corrected!

[artdf175]

You mention you have had fuel tank venting trouble.. having trouble filling with fuel is a potential sign the vent is plugged. spiders and some small bees are usual culprits take an air pressure hose and blow out the vent passages
amother sign is a relative flat fuel bulb, after you have run the engine for a short period. a plugged vent will cause a vacuum the then starve the engine of fuel
however, as Redlowery suggested, make sure the battery is fully charged. The ECU’s on our engines are very sensitive to voltage levels.
when running you have fully voltage from the engine, however when the rpm drops that level can drop off and the battery is needed to keep level the voltage
Art

[CaptainD]

sounds early in engine life to need an IAC? But stranger this have happened I guess? Sounds like your getting robbed of fuel or air or both somehwere

[Moonlighter]

It doesnt really sound like an IAC issue to me - usually people report difficulty starting and erratic high idling speeds.....the whole thing seems strange - especially that when it stalls, it starts right up and then runs fine? Unlike typical IAC issues.

What is the primer bulb like when the engine stalls? Is it empty? Soft at all?

If it was soft/empty, and given what you have said about difficulty fuelling and apparent vaccuum when the fuel cap is opened, i would be looking at the tank vent as has previously been suggested. Definitely try blowing thru it (with the tank cap off of course), there should be a clear flow of air.

If the boats fuel tank (most likley has) an anti-syphon valve fitted, I would dedinitely remove it and replace with a straight through fuel barb. i have personally experienced issues with these valves causing stalling when the engine is idling, as they can fail. At speed the engine fuel pump can overcome the restriction of a bad AS valve, but not at idle. Removing it will eliminate one potential source of fuel restrictions. (But it usually results in a soft primer bulb and would also normally see the engine stalling again at idle after restarting, but anyway, I would get rid of it.) they are not a necessary item and are a frequent source of problems.

Definitely check battery and make sure it is charged up and holding charge. Check (eg remove, clean and replace) main battery conmections and make sure they are tight. As Red and Art have indicated, these engines will do seriously weird things if they are not getting good 12V power.

The only other thing i can think of is stale fuel. Stale fuel usually smells “off” so check yours is good, if the boat has had little use, fuel can go off quite quickly, especially in hot conditions.