Mechanic to do a sea trial in cowichan bay

[wildmanyeah]

I have been through exactly the same thing and spent more than a thousand dollars on mechanics. I have shopped for new motors as also. I just seems that the motor is strong, has good compression, new reeds, rebuilt carbs, a new coil. It seems a shame to chuck it out if there is really nothing wrong with it. Plus I am thrifty, so there is that too.

I wish a mechanic would of told me at the start that the motor is dead and i should replace it.

ohyeah they also rebuilt the carb, tuned it. Also put all new gas in it and replaced fuel filter, also tried hooking up a auxiliary gas tank to eliminate it.

IT's a hugely frustrating issue as no one can tell me what's wrong with it and I have basically replaced every part surrounding the motor and it has good compression.

The second to last time i had it out it planned for 45 mins without an issue, once it got onto plane. The last time I had it out it planned out to duval and when i went to leave it died and had to put in on the kicker.

 

[triplenickel]

I'm thinking it must be something like this or the stator. I have had it to several shops in the Cowichan Valley. Some mechanics don't want to work on it due to it's age and the others dont want to sea trial it. No one has mentioned a dyno. I have been watching for a cheap parts motor so I can just start swapping out parts, but I dont want to put too much money into it in case that is not the problem. I am fairly competent when it comes to basic mechanics, but taking the ohm meter to the electrical system seems daunting.

Can you easily replicate the bog as in keep it in that range for a couple minutes? For safety sake see if you can do it on the trailer backed into the water first. Get a helper at the back of the boat while it’s bogging and pull one plug lead off at a time. You’ll be able to figure out which cylinder(s) aren’t firing, then go through the process of moving coils from a known good hole to the one that isn’t firing and see if the issue moves. Some of the older ones depending on size had multiple power packs so if coil swaps don’t move the issue try swapping the power packs around. I used to work at a merc dealer, I sold 100’s of power packs it wouldn’t even be a small surprise.

 

[SpringVelocity]

Usually if Jamie says its old bad sign. He usually has a network of used parts etc. Same with Jim at Mill Bay auto parts.

 

[ab1752]

I have not done that, I will give it a try. Would a spark / ignition problem not show up as hard to get up on plane, not like the motor is flooding out?

We just corrected a WOT issue on a 2008 Yamaha 150 4 Stroke that was cutting out hard only at WOT. Hey what's this loose ground all about...bammo fixed.

The other similar issue I have had is with dual carbs on my 240Z with one float not set equally to the other. It would rev out fine in the driveway but not under vehicle load but in that case, once fuel started to starve it would not correct itself. I do think that yours is a spark issue and I would go and clean and reseat every hot and ground connection in that engine. Then run it in the dark to see if you find any weird spark where there shouldn't be.

 

[ab1752]

I am too lazy to scroll up but have you done a compression test on this engine?

 

[fish brain]

I don't even want to talk about it, it makes me sick everytime i think how much i spent on it. I wish a mechanic would of told me at the start that the motor is dead and i should replace it.

ohyeah they also rebuilt the carb, tuned it. Also put all new gas in it and replaced fuel filter, also tried hooking up a auxiliary gas tank to eliminate it.

IT's a hugely frustrating issue as no one can tell me what's wrong with it and I have basically replaced every part surrounding the motor and it has good compression.

The second to last time i had it out it planned for 45 mins without an issue, once it got onto plane. The last time I had it out it planned out to duval and when i went to leave it died and had to put in on the kicker.

I have been through everything you mentioned, even the part where it will work of a trip or two. It sucks when you know the motor can work and it won't, and there seems to no good reason for it. If I could be convinced it was pooched I would replace it, I'd just like to hang on to my $20k a little longer

 

[fish brain]

We just corrected a WOT issue on a 2008 Yamaha 150 4 Stroke that was cutting out hard only at WOT. Hey what's this loose ground all about...bammo fixed.

The other similar issue I have had is with dual carbs on my 240Z with one float not set equally to the other. It would rev out fine in the driveway but not under vehicle load but in that case, once fuel started to starve it would not correct itself. I do think that yours is a spark issue and I would go and clean and reseat every hot and ground connection in that engine. Then run it in the dark to see if you find any weird spark where there shouldn't be.

I will give it a go, can't hurt

 

[fish brain]

I am too lazy to scroll up but have you done a compression test on this engine?

I don't think I posted compression. it's around 120 per cylinder.

 

[fish brain]

Can you easily replicate the bog as in keep it in that range for a couple minutes? For safety sake see if you can do it on the trailer backed into the water first. Get a helper at the back of the boat while it’s bogging and pull one plug lead off at a time. You’ll be able to figure out which cylinder(s) aren’t firing, then go through the process of moving coils from a known good hole to the one that isn’t firing and see if the issue moves. Some of the older ones depending on size had multiple power packs so if coil swaps don’t move the issue try swapping the power packs around. I used to work at a merc dealer, I sold 100’s of power packs it wouldn’t even be a small surprise.

You can swap the power packs back and forth and change the way the engine runs?

 

[noluck]

it is most likely a lean condition, so giving a little chock will help determine it, i don't think i have ever seen a rich condition with a jetted carb

 

[Island Fish Lifter]

You havnt said what size outboard it is.. v-6? 150 black max probably?

 

[Island Fish Lifter]

Older carbureted Mercs are completely different from Japanese units like yamahas and Honda’s. Like comparing apples to oranges. Also omc’s are completely different than mercs. But like I said, need to know the size and maybe model before I can offer any useful info.

 

[triplenickel]

You can swap the power packs back and forth and change the way the engine runs?

Only in that it can change which hole isn't firing if that's the issue. While it's bogging pull off a plug lead see if it changes the way it runs, if it gets worse you know that one was firing, if it doesn't change you've found a hole that's not firing. Then do the next, and then the next until you find the one(s) that don't affect the way it runs. Then swap coils between a hole that changed when you pull the plug lead and one that doesn't change when you pull the lead. If the misfire moves when you move the coil, you've found the issue, if the problem hole doesn't follow the possible bad coil then swap the power packs and see if the problem hole changes. Hope that makes sense!

 

[fish brain]

Older carbureted Mercs are completely different from Japanese units like yamahas and Honda’s. Like comparing apples to oranges. Also omc’s are completely different than mercs. But like I said, need to know the size and maybe model before I can offer any useful info.

It's a Merc 150 Off Shore

 

[fish brain]

Only in that it can change which hole isn't firing if that's the issue. While it's bogging pull off a plug lead see if it changes the way it runs, if it gets worse you know that one was firing, if it doesn't change you've found a hole that's not firing. Then do the next, and then the next until you find the one(s) that don't affect the way it runs. Then swap coils between a hole that changed when you pull the plug lead and one that doesn't change when you pull the lead. If the misfire moves when you move the coil, you've found the issue, if the problem hole doesn't follow the possible bad coil then swap the power packs and see if the problem hole changes. Hope that makes sense!

I have pulled the plug wires in the yard, and I think Issac at Coastal outboard did that also, as he is the one who thought it might be an intermittent coil. It has not been done under load

 

[fish brain]

it is most likely a lean condition, so giving a little chock will help determine it, i don't think i have ever seen a rich condition with a jetted carb

I don't know when I can get back to the boat, but if the problem is persisting, I will try this

 

[triplenickel]

I have pulled the plug wires in the yard, and I think Issac at Coastal outboard did that also, as he is the one who thought it might be an intermittent coil. It has not been done under load

You gotta be able to do it while the issue is present to mean anything.

 

[Viking]

Sounds like the timing isn't advancing smoothly through the power range. What controls and sets the timing??? Black box... weak trigger..

 

[fish brain]

Sounds like the timing isn't advancing smoothly through the power range. What controls and sets the timing??? Black box... weak trigger..

good question. I will have to read the book on how to advance the timing by hand

 

[Island Fish Lifter]

I’ve been a mechanic for many years. From the limited info I have here, could be a number of things. First of all, those older carbureted v6 mercs use two swithboxes one runs each bank of cylinders. OMC calls them power packs.
If one fails, you will only have 3 operating cylinders and any speed.
These older mercs also use a high and low speed stator. If the high speed stator is failing, you would run fine at low speeds, but would not function properly at higher RPMs. To properly troubleshoot this, I would need more info, like at what RPM it loses power.. etc.. this is not something that can be easily diagnosed by keyboard warriors, however well intentioned.