Fouling #1 plug - 200 opti

[kmagnuss]

Hi guys. Happy to have found this forum. Seems like there's a wealth of knowledge on here. I learned how to replace the compressor and get the injectors cleaned because of BBC, so thank you.
On to the problem:
I've been battling a misfire for a few months now. It typically starts in the upper RPM's, say 4500 or so, while cruising. I replaced the plugs and wires, and noticed that one of the wires was dry rotted, and also that the #1 cylinder plug was fouled. Boat ran like a top for probably 10 hours and then the misfire came back. #1 plug was fouled again. Next time out my compressor seized up (unrelated I figure), so I replaced that with a new one and also had all 12 injectors cleaned and flow tested. A couple of them were pretty fouled up according the the flow sheets. Put it back together and it ran better than ever. Then, like clockwork, 10 hours later that #1 plug is getting fouled again, causing the misfire. I tried a new coil and the problem came back. I'll be doing a compression check here shortly, but I'm wondering if a chipped or not sealing reed valve could cause this? Anything else I should check for? All new filters, cleaned compressor strainer, poppet valve, thermostats (newer style), fuel lines.
On a possibly somewhat related note... my boat seems to go through more oil than my old 150 opti I had did.. a lot more. Probably around 30:1 or so. (even before I put it in break in mode after the compressor change... which was 20 hours ago or more)

Thanks in advance.
-Mag

1. 0t019180
2. 2000 Optimax
3. Tempest plus 24
4. 5600 rpm
5. No idea
6. The old 3 light round gauge and an analog tach

[fishing122]

Did you inspect the reeds? Ahh just saw you said something about them. I would take a hard look at them.

[Kevinweir]

I’m fighting the same isuee with good old number 6. Lots of compression but keeps foulding the plug.

[JOE54]

check both for turned sleeves

[Kevinweir]

? Turned sleeves. So I’m only guessing what your saying is that the sleeves in the cylinder have turned and that’s what’s causing the fouling of the plugs?

[JOE54]

possibly, seen 2 that no one could stop plugs from fouling on, was just a smidge low on comp in that cyl, bore scoped bingo

[EuropeanAM]

Also- you mentioned getting the injectors cleaned. Who did the fuel rails, hoses, and validated the Injectors/Direct Injectors?

[kmagnuss]

Sorry guys... didn't get any emails to tell me this post had responses... probably went into junk mail.

Dale at injectorman.com did my injectors.

I took the reeds out today and one of them had a chip in it about the size of a dime cut in half. It was on the third bank of reeds from the top. Could this cause the #1 cylinder to foul?
Also... I had A LOT of oil residue around the intake, intake plenum, and reeds... I assume this reed that wasn't sealing could be causing this?

I have a new set of TDR reeds from European Marine to go in... thanks for your help.

Thanks again guys. I'll let you know how it goes when I get it back on the water.

-Mag

[Savage]

Left over oil in the plenum is perfectly normal.

[EuropeanAM]

Bad reeds on #3 could indeed cause a rich running condition on #3, as well as other (especially adjacent) cylinders.

[kmagnuss]

I was digging around a bit this evening, trying to chase down what I thought could be a bad ground. Symptom was that at high rpms if I used the trim, the motor would bog down some. I remembered somebody on here writing that the liquid tape they used had made it so there was a bad connection on one of their wires, and all of these problems seem to have started around the same time that I put new battery cables on and used liquid tape on the studs/nuts. So I cleaned up all the connections, cleaned up the grounds, and in the process I knocked the #1 spark plug wire off... wait what? Yeah... the wire was barely hanging on there. Oh I checked all the plug wires beforehand alright... on the plug side. This one was loose on the coil side. And now you know... I'm an idiot.

-Mag

[EuropeanAM]

Hopefully that resolves your remaining problem so that you can enjoy the engine now!

[Savage]

Mistakes happen........atleast you figured it out!

[kmagnuss]

Still running rough. Bummer. Need to check the compression to rule that out.

[kmagnuss]

Did compression check today. Engine warm, full throttle, all plugs out... got between 75-80 across the board. Seems low but maybe it's my $20 amazon compression gauge?

[kmagnuss]

Think it's possible that this is from being over-propped? I have a 24 pitch prop on there now, which is perfect when it's just me in the boat. But when I put a couple more guys in the boat it's definitely too much prop... and coincidentally this is the time I typically get the misfires starting. Hmmm...

[EuropeanAM]

Did compression check today. Engine warm, full throttle, all plugs out... got between 75-80 across the board. Seems low but maybe it's my $20 amazon compression gauge?

Likely is the gauge. Unusual to have a skip directly tied to "load"- but it may potentially have some bearing on the situation.

Have you clipped a timing light to each plug wire one at a time, while it is "skipping"?

[kmagnuss]

Have you clipped a timing light to each plug wire one at a time, while it is "skipping"?

I haven't, but it's easy enough to do. I'll try that when it starts acting up again in a few hours. :)

[kmagnuss]

Ran it with a timing light today... Spark is there at all times.

[EuropeanAM]

Let's back up a couple steps:

-Reed cages lapped, TDR Reeds Installed, Correct?

-Spark Plugs Inspected (better yet, replaced)?

-Plug wires in pristine condition (not nicks, worn spots, chalky-leakage type marks)?

If all above are YES, try a known-good MAP sensor (from another properly running Optimax if you can find one). Sometimes oil will become lodged in the neck of the MAP and dampen/distort it's function, and can cause strange performance problems such as you are having.