So just looking for some ideas. Christmas day fishing trip and it was cut a bit short. Did have fun and bought a bunch of snapper and a couple sharks. So ran fin till today. In the morning it started fine and ran wonderful. Than after a long run it would stall while throttling down. Symptoms got worse throughout the day. Would fire up but instantly stall. Goosed the throttle to choke the engine and it it would start. Towards the end of the day it would not turn for at all dripping no to 500rpm and stalling. Only way I got it back was to manually push the throttle blades open at the engine to keep it idling then had my son put it in gear throttle up a bit till the engine would hold rpm without intervening. Did some searching and see issues with the IAC valve that would similar to what I’m experiencing. Thoughts?
Small update and a BIG shout out to @JCDesigns
In-between everything going on in his life James was kind enough to carve out a small chunk of time to listen to my YamaStall whoas and provide a bit of guidance.
We discussed several possibilities but agreed it best to start with a stepped approach. One thing at a time. First order of business remove the IAC Valve and give it a good cleaning. As you can see from the pictures it was gunky. (is that a word?)
I reassembled the IAC and installed it back on the engine. SUCCESS!!! It fired right up and purred like a kitten. So I let the engine idle for a bit to warm up. Figured no test is complete if the outcome can’t be repeated so I shut it off after several minutes and fired it back up again. This time it was a bit more labored in starting and the RMP dropped by about 100 RPM down to 600 RPM. Hum… this is not promising. I revved the engine up to about 1500 RPM and brought it back and the engine stumbled a little. So I shut it down and tried to fire it back up again. No joy. Now it would not re-fire.
Did a little more testing but the results were the same.
James and I spoke later in the evening and we both have come to a common conclusion. The gunkieness (that can’t be a word) of the IAC may be part of the issue. The other part is probably the stepper motor in the IAC is going bad due to either worn condition or contamination. Net result, replace said part.
Jumped on boats.net yesterday and ordered a new IAC. Should be here in a couple days.
In the meantime I’m going to fully disassemble (i.e. destructive disassembly) the old IAC to see how it works and see if I can find the root cause. I’ll post the results when I have them.
Once the new IAC arrives I’ll install it and retest.
Thanks again for all your help @JCDesigns !
Cheers
