engine miss firing

[drpete3]

Nice

What i meant to say was Thank you to all you guys that shared their knowledge. Really Thank you very much.

I am heading to lake st clair next weekend and have been planning this trip for 3 months and its going to be my biggest hoooraaa of the summer. So I am so glad I can still attend. Great job guys!

Also I was concerned about somthing worse like losing a lobe on my cam or somthing really bad.

[Ratickle]

Ok i took the boat out now that I added dry gas and still had the problem....prob not bad gas. BTW it was no longer surging it was just plain missing.

So this moring I pulled all the plugs and found one not very tight when taking it out. Put te plugs back in and fired it up on the hose and sounded good again. so I took it down to the lake. Ran strong for about 5 min then started up again. So i figured i either tepmrarily fixxed the problem or this is a warm engin prob. So I pulled all the plugs agian. I broke an insulator on one of the plugs this time. Maybe it was cracked and i didnt notice it before. Put in a new spare plug checked all of the plug wires and boom. the boat ran great all day today. FEWWWWW! i am so relieved that i got it fixxed

Nice

Curious Jim, root cause bad/loose plugs? Why would it take time to appear?

[drpete3]

Im not sure it was the lose plug. what about a bad insulator? maybe even a wire not on tight. as I look at the engine it was the left side with a lose plug 2nd from the back and the 4th from the back on the left seemed to not be on good.

the broken plug was on the right side and was the 3rd from the back.

Sorry i dont know which cylinder is which 1-8

[Ratickle]

Im not sure it was the lose plug. what about a bad insulator? maybe even a wire not on tight. as I look at the engine it was the left side with a lose plug 2nd from the back and the 4th from the back on the left seemed to not be on good.

the broken plug was on the right side and was the 3rd from the back.

Sorry i dont know which cylinder is which 1-8

That's okay, I'd have to look it up too.


Just trying to figure out root cause so if someone else asks with the same type of issue we can steer them correctly as one of the possibilities.

[drpete3]

also, all of the plugs looked light brown or tanish.

one thing I noted was 2 plugs on the left side (front 2) had droplets of some liquid on the center electrode when the were first pulled. not sure if that means anything.

[Ratickle]

also, all of the plugs looked light brown or tanish.

one thing I noted was 2 plugs on the left side (front 2) had droplets of some liquid on the center electrode when the were first pulled. not sure if that means anything.

This was the very first time out this year, correct?

[drpete3]

This was the very first time out this year, correct?

No I have put about 9 hours on it before these symptoms started. Remember this was a rebuilt engine. I got it in the water over memorial day and been out a few times since then. Then you know the story. Started surging then I m pretty sure was just running on 7 cyl. All in all prob took abou tan hour of run time to go from surging to just missing.

Fyi, Jim I put in 89 oct today figured it cost me about an extra $1.50 for 15 gal to top it off.

[MOBILEMERCMAN]

Since you mentioned unknown liquid on plug I would suggest you check the plugs again since you have run it.. Make sure the exhaust isn't leaking. Water from a leaking exhaust will make it miss. It will show up on the plug with water drops or rust spots.

The loose plug will make it miss. A loose wire will fall off. Broken insulator can be from installation, lean, or water leaking.

[MOBILEMERCMAN]

When the motor was redone did you check your exhaust and/or change your riser gaskets?

[Ratickle]

Since you mentioned unknown liquid on plug I would suggest you check the plugs again since you have run it.. Make sure the exhaust isn't leaking. Water from a leaking exhaust will make it miss. It will show up on the plug with water drops or rust spots.

The loose plug will make it miss. A loose wire will fall off. Broken insulator can be from installation, lean, or water leaking.

When the motor was redone did you check your exhaust and/or change your riser gaskets?

Why the surge though?

[MOBILEMERCMAN]

Why the surge though?

I don't know. It is hard to interpret others descriptions some times..

Liquid on the plugs is more clear. I wonder why was motor redone?

[drpete3]

The only time I had a liquid on the plugs was the first time I pulled them. the second time they were all dry.

The reason i needed a new engine was becasuse it had a cylinder failure on the old block. It was a cylinder that had been sleeved. I dont know why the sleeve didnt hold up though. So in onther words I dont know why I had a failure. was it just the sleeve failed or was it some other factor. So what I really got was a long block the used my old parts to build the new engine.

I am sure the guy that rebuilt the engine used new gaskets on the manifolds but the risers hmmm not sure. Probably not. I have stock exhaust/not high performance.

Now what?

[Chris]

The first rule in racing is never trust a new part. Put it on and make sure it works, then put it away until you need it.

I've seen plenty of bad-out-of-the-box parts. And beyond that, if something has a defect, it's going to show up quick.

[drpete3]

The first rule in racing is never trust a new part. Put it on and make sure it works, then put it away until you need it.

I've seen plenty of bad-out-of-the-box parts. And beyond that, if something has a defect, it's going to show up quick.

Chris Im not sure what your referencing here. Or are you saying just the whole situation in general.

[drpete3]

I spoke to my engine builder and he said with out looking at it he wasnt sure either. The more i think aobut the liquid on the electrode the more i think it was water. It was beaded up on the electrode but these dropletts were tiny. Very tiny and only a few of them. He said it could have been condensation from sitting outside and a cool night.

[Chris]

Yes- as a general rule.

I just bought all new ignition stuff for my son's Tahoe. Put it all on and no start. Made me nuts for a full day of poking around. Finally, I started backing up one piece at a time. Put the old distributor cap on and it fired right up. Returned the first one and put the new one on- no start. Returned that one and put a 3rd one on- stared and ran poorly. Finally bought another brand and it ran fine.

[MOBILEMERCMAN]

I spoke to my engine builder and he said with out looking at it he wasnt sure either. The more i think aobut the liquid on the electrode the more i think it was water. It was beaded up on the electrode but these dropletts were tiny. Very tiny and only a few of them. He said it could have been condensation from sitting outside and a cool night.

Riser gaskets on stock exhaust need to be changed every 3 or 4 seasons in fresh water and every other season in salt. They do a lot of work separating exhaust from water in a small area. As time passes the gasket begins to weep water into exhaust.. At first it is hard to recognize. Soon it will begin to miss on a long idle but, clear as you rev it past 2k for a moment. Eventually it starts to leak some much the starter sounds like it is going bad when you try to start it.

I don't know if it is your problem but, it is a common service item that often gets overlooked.

[drpete3]

Riser gaskets on stock exhaust need to be changed every 3 or 4 seasons in fresh water and every other season in salt. They do a lot of work separating exhaust from water in a small area. As time passes the gasket begins to weep water into exhaust.. At first it is hard to recognize. Soon it will begin to miss on a long idle but, clear as you rev it past 2k for a moment. Eventually it starts to leak some much the starter sounds like it is going bad when you try to start it.

I don't know if it is your problem but, it is a common service item that often gets overlooked.

good point. Ive only owned this boat since aug of 2007 and I know I havnet replaced the gaskets on the risers so I shouold look into this. Actually what I would like to do is find some take offs(manifolds and risers )and get rid of the stock exhaust

[MOBILEMERCMAN]

Stock exhaust on stock motors work well. The riser gasket change is about an hour each. Pretty easy and inexpensive. In fresh water the manifolds and risers last a long time.

[drpete3]

Stock exhaust on stock motors work well. The riser gasket change is about an hour each. Pretty easy and inexpensive. In fresh water the manifolds and risers last a long time.

got any part diagrams to see what I would be pulling off and replacing. I know its somthing I can do just never done it before. Like you said it may not be a problem but if its semi routine maintenance then I should jus tdo it before I have a problem.