Need help--older Mariner 40EL rough idle with bad shaking in gear

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BrounHownd
Posts: 16
Joined: 25 Feb 2021, 20:36
Location: Camden, SC

Need help--older Mariner 40EL rough idle with bad shaking in gear

Post by BrounHownd »

Advice just like NC Cat?

You mean that my whole issue is because I'm using a trash can? That I clearly stated it was doing the exact same thing on the water BEFORE the trash can ever came into the picture? I appreciate the thought, but I really don't see the connection--it came across as someone that doesn't have an answer but has to say something anyway. Sorry I responded in kind.

Advice like the left field stuff you've offered in some of your posts in the past?

I'll pass, friend. You're welcome to move along.

MrGiggles
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Need help--older Mariner 40EL rough idle with bad shaking in gear

Post by MrGiggles »

Running in a barrel will get you close, however, most service information recommends setting the idle jets in gear, at idle speed. In my experience, putting the outboard in gear in a barrel results in an empty barrel and wet pants.

Get it close in the barrel and fine tune with the motor idling in circles on the lake. There are usually rubber plugs that you can pop out of the air box to access the screws, without removing anything but the cowl.

The thing you shouldn't do is set them on muffs, your settings will be way off without the back pressure from the exhaust being submerged.

Give the adjustable gap tester a try, make sure it will jump a pretty large gap, around 3/8-1/2" is pretty acceptable.

Resistance testing is largely useless, you need a DVA to properly load the components and get an accurate measure of their performance, but that is really only necessary if you have found a weak/no spark condition.

I think you are on the right track of going through the link and sync procedure, as well as getting the idle jets set properly. I would also do a quick compression test as well, just to ensure you aren't chasing your tail.

Additionally, you can pull the plug wires one at a time with a well insulated pair of pliers to narrow down which cylinder is misfiring.

BrounHownd
Posts: 16
Joined: 25 Feb 2021, 20:36
Location: Camden, SC

Need help--older Mariner 40EL rough idle with bad shaking in gear

Post by BrounHownd »

MrGiggles wrote: 07 Apr 2021, 20:12 Running in a barrel will get you close, however, most service information recommends setting the idle jets in gear, at idle speed. In my experience, putting the outboard in gear in a barrel results in an empty barrel and wet pants.

Get it close in the barrel and fine tune with the motor idling in circles on the lake. There are usually rubber plugs that you can pop out of the air box to access the screws, without removing anything but the cowl.

The thing you shouldn't do is set them on muffs, your settings will be way off without the back pressure from the exhaust being submerged.

As for your issue, if you are getting a good, fat spark like you say, there is no point in going any further with ignition system testing.

Resistance testing is largely useless, you need a DVA to properly load the components and get an accurate measure of their performance, but that is really only necessary if you have found a weak/no spark condition.

I think you are on the right track of going through the link and sync procedure, as well as getting the idle jets set properly. I would also do a quick compression test as well, just to ensure you aren't chasing your tail.
Good stuff. Thank you. Luckily my setup stays pretty full when I put it in gear, but I see how it could be an issue. I just need to get it to a point it's not shaking my fillings out before I clock out on a weekday and drive all the way to the nearest quiet ramp with a dock.

Haven't had time to hook everything back up since I put a meter to the ignition system, but I'll keep you posted. Having that manual specific to the motor has been a huge help. Plan to see if the timing adjustment and linkage reset help. Carbs were synced when I put them back on....they open at exactly the same time and move together with the idle screw.

As to spark, best I can see is that there is spark there...it's a side console and I don't have a remote switch. Can't tell the quality. But have a timing light I borrowed I can use to look for misses once I reconnect it all if the other work doesn't improve things.

MrGiggles
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Location: Springfield, MO

Need help--older Mariner 40EL rough idle with bad shaking in gear

Post by MrGiggles »

BrounHownd wrote: 07 Apr 2021, 20:29
MrGiggles wrote: 07 Apr 2021, 20:12 Running in a barrel will get you close, however, most service information recommends setting the idle jets in gear, at idle speed. In my experience, putting the outboard in gear in a barrel results in an empty barrel and wet pants.

Get it close in the barrel and fine tune with the motor idling in circles on the lake. There are usually rubber plugs that you can pop out of the air box to access the screws, without removing anything but the cowl.

The thing you shouldn't do is set them on muffs, your settings will be way off without the back pressure from the exhaust being submerged.

As for your issue, if you are getting a good, fat spark like you say, there is no point in going any further with ignition system testing.

Resistance testing is largely useless, you need a DVA to properly load the components and get an accurate measure of their performance, but that is really only necessary if you have found a weak/no spark condition.

I think you are on the right track of going through the link and sync procedure, as well as getting the idle jets set properly. I would also do a quick compression test as well, just to ensure you aren't chasing your tail.
Good stuff. Thank you. Luckily my setup stays pretty full when I put it in gear, but I see how it could be an issue. I just need to get it to a point it's not shaking my fillings out before I clock out on a weekday and drive all the way to the nearest quiet ramp with a dock.

Haven't had time to hook everything back up since I put a meter to the ignition system, but I'll keep you posted. Having that manual specific to the motor has been a huge help. Plan to see if the timing adjustment and linkage reset help. Carbs were synced when I put them back on....they open at exactly the same time and move together with the idle screw.

As to spark, best I can see is that there is spark there...it's a side console and I don't have a remote switch. Can't tell the quality. But have a timing light I borrowed I can use to look for misses once I reconnect it all if the other work doesn't improve things.
Leave the ignition key on, and rig up a short jumper wire on the starter solenoid, which is conveniently located under the cowl, to crank without using the ignition.

An adjustable gap tester is needed to measure ignition performance. Just having spark at the plug is not enough, since the resistance of air goes up when it is compressed and heated, could have good spark out of the cylinder and nothing under compression.

BrounHownd
Posts: 16
Joined: 25 Feb 2021, 20:36
Location: Camden, SC

Need help--older Mariner 40EL rough idle with bad shaking in gear

Post by BrounHownd »

MrGiggles wrote: 08 Apr 2021, 08:23 Leave the ignition key on, and rig up a short jumper wire on the starter solenoid, which is conveniently located under the cowl, to crank without using the ignition.

An adjustable gap tester is needed to measure ignition performance. Just having spark at the plug is not enough, since the resistance of air goes up when it is compressed and heated, could have good spark out of the cylinder and nothing under compression.
Great idea--not sure why it didn't occur to me to do that.

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RaisedByWolves
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Location: Bucks county PA.

Need help--older Mariner 40EL rough idle with bad shaking in gear

Post by RaisedByWolves »

BrounHownd wrote: 07 Apr 2021, 19:24 Advice just like NC Cat?

You mean that my whole issue is because I'm using a trash can? That I clearly stated it was doing the exact same thing on the water BEFORE the trash can ever came into the picture? I appreciate the thought, but I really don't see the connection--it came across as someone that doesn't have an answer but has to say something anyway. Sorry I responded in kind.

Advice like the left field stuff you've offered in some of your posts in the past?

I'll pass, friend. You're welcome to move along.
The fact that you dont see the connection is how we got here in the first place.

In short, without the prop in clean water moving the boat you will never set the idle properly.

Maybe read a service manual, its in there.

Knowing this, anyone who has any common sense (Which isint all that common) would spend 5-10 minutes at least trying to adjust the idle on the water like the service manuals state before doing anything else. Its free and simple once you see the connection.

Finally, as to the part in red, please.....please.. point out all of my "Left field Stuff" in "some of my posts" in the past.

Im sure it will be a hoot.
Sailbad the Sinner

CedarRiverScooter
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Need help--older Mariner 40EL rough idle with bad shaking in gear

Post by CedarRiverScooter »

Not to confound the issue, but long ago I had a motor with exhaust leak under the shroud & it would idle poorly.

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RaisedByWolves
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Location: Bucks county PA.

Need help--older Mariner 40EL rough idle with bad shaking in gear

Post by RaisedByWolves »

CedarRiverScooter wrote: 09 Apr 2021, 17:30 Not to confound the issue, but long ago I had a motor with exhaust leak under the shroud & it would idle poorly.
Was this while it was in a barrel or on the lake? :lol:

Makes perfect sense though as its rebreathing its own exhaust.

Once the revs went up it was probably pulling in enough fresh air to run properly.

But what the hell do I know, I'm full of bad advise.
Sailbad the Sinner

CedarRiverScooter
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Joined: 13 Nov 2014, 08:01
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Need help--older Mariner 40EL rough idle with bad shaking in gear

Post by CedarRiverScooter »

On the river. It was a 125 'rude, was strong motor!

I paid to have the gasket replaced. That helped but that motor never idled smoothly.

BrounHownd
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Joined: 25 Feb 2021, 20:36
Location: Camden, SC

Need help--older Mariner 40EL rough idle with bad shaking in gear

Post by BrounHownd »

As an update and to provide some closure....

Pulled the carbs apart again, cleaned them again, focused on the idle jets and passages again.

Drove the hour to the nearest quiet ramp with a dock so I wasn't using my trash can. Ran the boat to warm it up. Tied it to the dock and went through the link, sync, and idle adjustment process again. Better, not fixed. Still sounds like a miss/stumble at idle.

Drove the hour back home. Replaced the CDI unit that tested bad (according to the service manual, which I keep getting told to read by the same people that seem to think it's not useful). Put it in the test tank. Idles like a 40-year-old motor could be expected to after some minor adjusting.

I'll be sure to report back after I get a chance to put it back in the water, but I think the test tank got me close this time.

I appreciate the useful feedback I've received and will hang around here reading and learning until the next issue crops up.

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RaisedByWolves
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Need help--older Mariner 40EL rough idle with bad shaking in gear

Post by RaisedByWolves »

BrounHownd wrote: 14 Apr 2021, 15:02 As an update and to provide some closure....

Pulled the carbs apart again, cleaned them again, focused on the idle jets and passages again.

Drove the hour to the nearest quiet ramp with a dock so I wasn't using my trash can. Ran the boat to warm it up. Tied it to the dock and went through the link, sync, and idle adjustment process again. Better, not fixed. Still sounds like a miss/stumble at idle.

Drove the hour back home. Replaced the CDI unit that tested bad (according to the service manual, which I keep getting told to read by the same people that seem to think it's not useful). Put it in the test tank. Idles like a 40-year-old motor could be expected to after some minor adjusting.

I'll be sure to report back after I get a chance to put it back in the water, but I think the test tank got me close this time.

I appreciate the useful feedback I've received and will hang around here reading and learning until the next issue crops up.


Curious as to why you chose to replace the suspect CDI after you drove an hour to the lake and back.

Something is not adding up here.

Who was it that told you the service manual was not useful?

I dont remember that.
Sailbad the Sinner

nytebyte
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Need help--older Mariner 40EL rough idle with bad shaking in gear

Post by nytebyte »

You're test tank is fine for initial tunning but you might want to have a fan blowing if it looks like its is getting a lot of exhaust fumes being sucked in as that will afect the idle. I have tuned many motors in a test tank and a few may need a final adjustment on the lake but you will be close in your tank.