08 PCM 343 misfire?

[aZ`]

Hi all,
Had the boat out last week end and it developed what sounded/felt like an ignition misfire. It only did it once, for a period of about 5-8 seconds whilst under full load getting onto plane. It hasn't done it before and didn't do it again, we used the boat for approx 1.5hrs run time there after.

I don't see many misfire related threads on here which tells me the ign systems are generally fairly reliable and indeed the plugs appear to be the original set (41-993) and same goes for the leads. I pulled a few plugs and all looked OK. Boat has 260hrs on it.

My question is, is there somewhere else I should be looking? do the HT leads wear/fail?

It certainly didn't feel like a fuel supply problem as it still pulled out with 3500lbs+ of ballast and people. Power didn't noticeably drop while misfiring and sounded like only one cylinder was to blame.

any ideas?

[Neverenough]

When was the last time fuel filters were changed

[G]

I have a 03 330 Ex.. And Mine developed a "bobble" " misfire" and would spit back every now and then and i took the distributor cap off and there was alot of corrosion in there. I orderd a new rotor button and cap and haven't had any issues since. I'm thinkling I had a crack in my cap letting moisture in. May want to check there.

[Quinner]

My first thought was cap/rotor then read G's post, would definitely check the cap/rotor. When replacing mine could not see any difference between the original parts and a standard A/C Delco replacement, they did not appear to be "Marine" specific so you may be able pick up a replacement at the local Napa/Auto parts store, that's what I used without issue.

Inspect the coil wire connection also while there.

Good Luck

[G]

Quinner is right on the money. I got my Rotor button at the local Napa store, but I got my Cap from White Lake since I was placing an order for other things, but they were the exact same price as the Napa store on that part. So I'm sure you can get those local and be back in business in no time.

[aZ`]

Thanks guys. I think you were on the money, took the dizzy cap off and found a fair amount of corrosion on all the posts. Unfortunately here in Aus the GM dizzy cap is not something that is easily sourced, so i will have to order one. In the mean time I have cleaned up all of the posts on the old one. Not able to properly test for 2 weeks, but in the driveway it fired up much quicker than usual and idled a lot smoother as well.

As for fuel filters, I only bought the boat in June, so cannot say for sure when they were last done. However I am making my way through every preventative maintenance part on the boat and trailer.

[G]

Good Deal.. Yeah When mine first did that, I cleaned all the post and the button with emory cloth and contact cleaner and it lasted about a month before it was corroded back up again, so there was a moisture getting in from somewhere, after I replaced the cap it hasn't done it since. You can order all those parts from White Lake Marine and have them shipped to you so you don't have to run everywhere looking for the parts, and like I found out there prices on that stuff were the same as the local parts houses. Good Luck.

[Quinner]

When you place your order consider including Cap, Rotor, Spark Plugs, Impeller and the FCC filter. May even want to double up on the FCC filter if they are hard to come by down your way.

[Sac Surfer]

I have an 2010 210 with about 185 hours on it. I did the cap, rotor, plugs, both fuel filters. Before I changed them all I did have a backfire or 2 when running at cruising speeds. Swap those parts out an she will be running smoothly again. Just make sure you note the cap, it looks like it can go on 2 ways and then make sure your wires are to the correct plugs.

[aZ`]

...and it lasted about a month before it was corroded back up again, so there was a moisture getting in from somewhere, after I replaced the cap it hasn't done it since.

I've always heard the theory of the cracked dizzy cap but never seen one. I'm not saying you're wrong but I would have thought the surfaces between the cap and dizzy would leak just as bad as an invisible crack? But surely something was getting in if your problem returned in a month or so.


Also how often do you guys change the FCC filter? and do you do the inline filter near the v-drive at the same interval?

[aZ`]

I was wondering what those 2 paper filters with the blue ends were that came as spares with the boat. FCC filter done

OK can anyone talk me into paying $50 for a PCM or Accel dizzy cap, when I can buy a no name cap WITH BUTTON for 10 bucks?

[ski4evr]

I put the "brand name" cap and rotor on two years ago right before a vacation, and it failed on the second day. Cylinders were crossfiring and I never did get it figured out while in Alabama. got home and figured it out in the driveway, and been running fine on the $10 cap for two years now with no issues. 1998 vortec 350 truck parts work great except for the spark plug wires, they are too short.

[G]

Yeah your right. I couldn't see anything wrong with it, and it does seem like moisture can get between the cap and the distributor, too me also.... I can only speculate what i had going on cause my friends with the same boat and hours had zero corrosion and mine did, and his boat was stored outside and mine was in a climate controlled garage... most def. agree with ya there... : )

I have never changed my FCC filter. Was thinking about it also, but I've been hesitant cause when I changed it on my 88 Ski Nautique some years ago that turned into a all day Sat. project...

[aZ`]

I have never changed my FCC filter. Was thinking about it also, but I've been hesitant cause when I changed it on my 88 Ski Nautique some years ago that turned into a all day Sat. project...

yeah I was a bit worried and wasn't even going to attempt it right away after reading some of the horror stories on here, but the later model FCC with the clamp makes a filter change a 5 minute job

Ill try the cheapo cap and rotor, thanks for the assistance guys.