#3 Cylinder no spark when hot

[Quick-man]

1983 75 HP Rude
I decided to post a new thread with a new title for this issue.
I have been having this issue with this engine for a while now. At WOT the engine runs great for a short period of time then dies to 2100 rpm. I have found that the #3 cylinder has no spark when the engine heats up. Last night I had this issue and when I got back at the dock I unplugged #3 wire with no effect, pulled the plug and sure enough no spark, #1 and #2 have great spark. After checking the spark plug lead and swaping plugs to make sure those two things were good, I put everyting back the way it was and checked #3 again and still no spark. I let it sit and after about 1/2 hour I checked the spark again on #3 and there WAS spark, not as strong as #1 and #2. So it appears something is failing when the engine gets hot, could this be the coil, powerpack? Any tests that I can do to narrow this down. BTW each coil was 95-100 degrees F, when the failure occured. Thanks for the help.

 

[tashasdaddy]

Re: #3 Cylinder no spark when hot

before spending any money swap the position of the #3 coil, completely with one of the others. it the problem follows the coil replace it. if the problem stays with #3, probably power pack.

 

[Quick-man]

Re: #3 Cylinder no spark when hot

Thanks tashasdaddy,

Figured that was the way to go, the issue is that I have to go out and heat things up, before it fails. I am hoping it is a coil since Power Pack's are a bit more, but then again no one said boating was cheap.

 

[tashasdaddy]

Re: #3 Cylinder no spark when hot

it's worth the money to go take a spin. the difference in the cost of a coil, and a power pack, is worth the effort. and electrical parts are not returnable.

 

[iwombat]

Re: #3 Cylinder no spark when hot

Check where the #3 coil grounds to the block. I'm betting you have some charring there causing a weak ground that fails when it gets hot.

Just a hunch.

 

[Quick-man]

Re: #3 Cylinder no spark when hot

I'll take a good look around and see if I can spot something. I am really hoping it is either a ground or at worst a coil. Even though iBoats has the powerpack for 76.90 which is about half of what I saw them for, and a coil for 19.59...trust me I would rather pay the 19.59 but the 76.90 isn't that bad.

I'll have a look tomorow and if it is the coil or ground. If it is the coil I'll see if I can get one locally.

Thanks everyone!

 

[Quick-man]

Re: #3 Cylinder no spark when hot

So after looking at the engine in the daylight...all of the other attempts was when it was dark. I noticed water coming from betwen the adaptor assembly and the powerhead also there was water coming from the adaptor assembly and the exhaust housing. Humm I wondered why is this happening? Now remember that I bought this engine just this year from an idiot as it appears now.

So this is what was happening, The engine runs at the no wake speed then when I am running at WOT for as brief period the engine fails to achieve max rpm when the #3 cylinder dies. When at WOT for the short period of time the water (salt water) enters the area under the hood and splashes around and gets the #3 (lower) coil wet, and the exhaust gas (not to mention the salt air) enters the carbs and that drops the rpm as well.

By the time I get back to the dock at less than 2000 rpm and I shut down the engine and take the hood off there is no water left that you can see.

I loaded it back on the trailer took it home and after looking around I noticed that the 4 bolts that attach the adaptor to the mid trunk were missing??? and then after taking the cover off to get to the 6 bolts that attach the adaptor to the powerhead I found 1 missing, 2 broken and 3 as loose as you can imagine. Oh and those gaskets that are supposed to be there were not.

Buyer beware I guess...the only good thing is the compression is good and the engine was running strong when it was running. Have to locate 2 new buolts (23.00 ea) and the gaskets ~ 3.00 each. I'll be putting locktight on everything.

Thought I would pass this onto everyone so that they can learn a bit from me and hopefully not run into the same issue.

Take care and I'll let you all know how it runs when I locate the parts. If anyone knows where I can pick these up let me know. The model is a E75TRLCTE

Thanks for your help

 

[Quick-man]

Re: #3 Cylinder intermittent spark

Re: #3 Cylinder intermittent spark

I replaced the gaskets on the adaptor plate to Powerhead and to the exhaust inner portion. No water now but and I can get much farther out. Then it happened again lost #3. I replaced the coil and took it out again, this morning at 5am and was going for about 20 minutes and bang I loose #3 again. However unlike the last time it comes back and then becomes intermittent. Here is the blow by blow.

Go out past the no wake area (harbor)
Open her up, runs great for about 10 minutes WOT then drops #3
Lift the hood and look around all is dry and well.
A minute later #3 is back and I can get going again but not as long as before.
Getting back in to the harbor (no wake) #3 intermittently dies then comes to life.

Any thought on this I am out of ideas except a power pack that may be going, but I would expect a power pack to be a go no-go state.

 

[offshore100]

Re: #3 Cylinder no spark when hot

I think it might be a sensor coil under the flywheel. Had a 30 Mariner do that once, and that's what the problem was.

 

[Quick-man]

Re: #3 Cylinder no spark when hot

Is there any way to check that? How tough is it to replace?

 

[offshore100]

Re: #3 Cylinder no spark when hot

Pull the flywheel and look to see if there is any obvious damage to sensor coils (corrosion, etc.); if all look good, switch sensor coils, see if problem follows switch.

 

[Quick-man]

Re: #3 Cylinder no spark when hot

Problem solved. Or at least I think so, I replaced the Powerpak and the engine runs and runs without dropping spark on any cylinder. I was expecting it to die any second but it kept going so I am confident that the issue was the powerpack, this one was hard, since it would run great for an undetermined period of time then die. Then come to life again after sitting. It could have been worse it could have been the stator...yikes 100's for that.

Thanks for all the help and suggestions on troubleshooting this issue. It is much easier when you know you are not alone trying to figure this out. I am going out tomorrow morning for some fish, or just to play I'll post an update.