'89 Black Max - 135 V6 - Started and ran all day, stalled in neutral, Idle seems low

[aayjay]

For the first time since i had it, it stalled when i went into neutral. It did it twice on approching the dock. Ran all day no problem, hadn't been idling for any prolonged amount of time, so i don't believe the plugs are fouled, they are almost new NGK. I run high octane and put in ethanol stabilizer, I have about a half a tank of gas remeining. When I got home and put on the ear muffs to flush it it idled at around 500-600 rpms. It did not quit until I turn off the ignition. I will try charging the battery, as my system seems to be charging at only 12.8 volts, maybe 13, but I dont know exactly, as the gague is not as accurate as a meter. Is the charging system slowly going? These carbs were redone about 2 years ago according to the former owner, and all looks clean and nice under the cowl, boat has been used 12 times since Easter without incident and had strong idle until the end of today. Advice?

 

[jerryjerry05]

Re: '89 Black Max - 135 V6 - Started and ran all day, stalled in neutral, Idle seems

Start with a compression/spark test.
Get a test meter and check the voltage.
Post these results.J

 

[j_martin]

Re: '89 Black Max - 135 V6 - Started and ran all day, stalled in neutral, Idle seems

My XR4 did that to me.

I turned the idle adjust screw back in the 8 turns it had backed out, and this time I tightened the lock nut.

 

[aayjay]

Re: '89 Black Max - 135 V6 - Started and ran all day, stalled in neutral, Idle seems

compression is good 120 psi in all cylinders, how do i ccheck the voatage from the stator? this is a merc outboard, stator is red.

 

[j_martin]

Re: '89 Black Max - 135 V6 - Started and ran all day, stalled in neutral, Idle seems

Why do folks automatically try to talk themselves into messing with and maybe replacing the most expensive parts first?

Your problem is probably just tune in general. My first comment is more relevant than it seems at first. Normally out of the water it will idle slightly higher than in the water. Spec. is about 650 - 700 rpm, in the water, in gear for idle. All the power for the ignition system is generated on the fly, and doesn't come from battery, so if idle is too low, it doesn't take much to kill it. If your rectifier is shorted (sounds like it might be) and dragging the stator magnetics down a bit, that'd do it.

Yours idles at 600, out of the water, no load. Sounds a little low.

Set the idle speed to spec on the water, and look up the rectifier ohmmeter test in the FAQ on this site and check out the rectifier. It should be charging at near 13V at idle, and up to 15 V at speed into a full battery.

Would be worth your while to go through the link-n-sync procedure and put everything spot on, then troubleshoot from there.

hope it helps
John

 

[aayjay]

Re: '89 Black Max - 135 V6 - Started and ran all day, stalled in neutral, Idle seems

I adjusted the base idle up sligtly and it leveled out just fine, fires and idles with a bump of the key, yet the charge never gets above
13v according to my gauge and drops to 10v whan i turn the lights on. If the rectifier is shorted will this cause any long term issues? I have the old 2 wire yellow stator that they later changed out for a 4 wire dual regulator system. I heard that the deep cycle batteries do not charge well from either of these. Should I change the batteries or the rectifier or both? thanks for your reply, i had forgot about the regulator being separate on these outbaords.

 

[j_martin]

Re: '89 Black Max - 135 V6 - Started and ran all day, stalled in neutral, Idle seems

Check it with a real meter. Those numbers don't make sense.

 

[aayjay]

Re: '89 Black Max - 135 V6 - Started and ran all day, stalled in neutral, Idle seems

I looked at the rectifier/regulator which is a water cooled module bolted to the block between the heads and one of the coil pack bolts was right up against one of the red wires, so i insulated it and the voltage at idle went to 13.5 on the gauge at idle (i cant lay my hands on a meter right now). I am guessing that the lights are not causing a problem as they are probably drawing proper voltage when they are on, but the gague is reading a different voltage because of an issue with the wiring of the dash lights. I will test for any wiring shorts with the engine off and see what is what. Thank you for your continued advice, John...you da man.