Out of patience for this motor - 1986 Mercury V150

[Tx91z28]

Ok so I bought a 1986 merc 150, v6 motor for a pretty good deal, everything seemed to work, trim,remote controls, starter, started easy, idled a bit high on the muffs, compression was 115-120 on all cylinders, stainless prop, new trim pump, shifted nice, everything was good except I bought it off a test stand so I never load tested it but it reved great on the stand....

Hung on on the checkmate, figured I'd throw it in the water and see how it ran then tune it up from there. I splashed the boat, fired it up on the first crank (40:1 mix 93 octane) and let it warm up at the dock. Put it in gear, idled away from the dock, so far so good then I gave it some throttle and it bogs. At about 2/3 throttle it gets to 1500rpm and past that the rpms either stay at 1500 or drop off to 900 and it tries to die. I made sure the throttle cable was advancing the timing all the way and opening the carbs up and it all checked out. Back on the trailer, took it home.

I got out my manual, timing light, and started from step one. I proceded to set the timing EXACTLY as specified in the mercury manual. Well I found the brown and green wires on the switch box were backwards for #1 so I corrected that, then I find that the timing marks on the flywheel are off and #4 is the plug wire I have to reference to set the timing (used a depth indicator to verify the .462 mark lined up with .462 BTDC with #4)... Though it was weird, but i was able to set the timing using #4 as my reference. I checked all 6 plug wires for spark (usings tach on timing light) from idle to 4500RPM, they all checked out good except I noticed that #1 has a jumpy RPM signal to my timing light tachometer and reads high sometimes, not always but sometimes. I then sync'd the timing/throttle linkages as per the manual and other than a tiny clearance left between the throttle cam and roller at idle that went well.

Took it to the ramp, strapped down on the trailer, same result 1500rpm bog, idles really well now and it's running smoother and firing on what I think is all 6. While idling on the hose I see some oil/gas mix in the water puddle, and it will hiccup and let out a puff of blue smoke every minute or so at idle. I did have the timing light on the motor under load and i messed with the wot timing with the motor running and got it up to 1800 rpm at 24* BTDC but thats clearly not the solution so I set it back to spec.

So now I'm thinking I'll check for a fuel issue just incase, and go over EVERYTHING else while I'm at it.

Pulled the carbs, they have clearly been serviced recently they are clean and have new gaskets, jets are clean an correct, so I put them back on. I forgot to check float height, or the fuel pump . I prime the fuel system with the bulb and I see gas coming out of the port middle carb - awesome. I'm going to do a full rebuild on them this week.

Since the carbs checked out pretty ok I moved back to electrical. Found a new-ish CDI stator, old looking trigger, and a burned up rectifier (I replaced it). I ohm checked the stator and the red/blue and red-white/blue-white both had similar values, but they were both lower than the rage of values in the manual, the other values were spot on. Also ohm checked the trigger, everything was in range.

I am not new to engines at all, but big outboards are not my thing so I'm a bit stumped where to go from here. It really does not seem like a fuel issue to me, seems like an ignition thing. Is the fact that the flywheel is oriented incorrectly (lined up with TDC of #4) and there is a pickup magnet or something on the flywheel that the trigger uses, that would mess my timing up bad? I was going to pull the flywheel but I don't have a flywheel holder to let me get the nut off.

heres a vid:

http://youtu.be/bi7vemm2dqI

Any help is appreciated, thanks fellas

- Alex

[hydrostreamvking4m]

Stator.
Merc runs a 2 side Stator.Rpm 1500 and below is low side.Once ya jump up the rpm above 1500 rpms its on the high side..
So if it was my motor id replace the stator..Good luck and please do post what ya find fixs it..

[Tx91z28]

holy crap this forum responds faster than any I've ever been on - awesome!

Ok I had read that similar issues were caused from a bad stator, and the ohms where bad (wish I had a DVA...), i'll look into it tomorrow after work.

Let me ask you this:

I know the low speed coils on the stator get saturated at a certain rpm and then the high speed ones take over, but I don't understand what the stator actually is doing very well other than generating an ac current. What no longer happens (no power generated?) once the rpm threshold is reached? I see spark still at high rpm when free revving to 4000+, so what negative thing is happening with the bad stator?

[transomstand]

No mention of idle/advance modules, oil injection module, and whether or not those components are in thier correct place (in the bottom of the shop trash barrel)

[Tx91z28]

Both are long gone

[transomstand]

Timing marks off, reference # 4?

How far off is #1? (we've seen where people have disassembled flywheels, and put them back together wrong)

[perfmarine1]

I did not see a mention of a fuel check. Pump some into a clear jar and see if it is clear or has water/ethenol in it. If some wires were hooked up wrong on switch boxes they may be toast. That surly is not hitting on all 6 cyls. Check the stator ohms and DVA the blue and red wires if good replace switchboxes.

[Moonshot180]

Stator.

My 2.4 bridge did the same thing. Your current stator is generating just enough vac to keep the plugs lit at low rpm.

[Tx91z28]

I don't even see the timing marks when referencing #1.

Fuel is good, yellow to yellow ohmed in range, both red to blue pairs were low ( not in range)

Vac = volts ac?,

[transomstand]

I don't even see the timing marks when referencing #1.

That needs to corrected first.

[Tx91z28]

Is that a matter of flywheel orientation or something else?

[hydrostreamvking4m]

This link might give you some help...
http://www.hydrostream.org/ArticleArchives/Timing.htm

[transomstand]

Is that a matter of flywheel orientation or something else?

I would want a very close inspection of the flywheel. We've seen people remove the flywheel hub, and not install it in it's correct orientation. Check for loose, broken magnets. Best way is to install a known good flywheel if possible. Also need to be sure the stator is in it's correct position.

[daveswaves]

I don't even see the timing marks when referencing #1.

Fuel is good, yellow to yellow ohmed in range, both red to blue pairs were low ( not in range)

Vac = volts ac?,

Remember, those Ohm readings are to ground from each wire, not between the wires.

[Moonshot180]

You can get stators for around ~300 bucks.

Get ya a new stator from CDI or some other place and get back on the water.

Good luck.