8.1 Mercruiser Problems

Jesus , I'm an idiot. False alarm. While removing ignition switches I bumped the transmission lever slightly.
Back to the original , crank , no start even after switching ignition switches.
 
Update...Final update , I hope...

The port engine is running. Quite nicely. After spending all Sunday doing a pin out and not finding any shorts or bad grounds or broken wires , I was feeling defeated.
If you remember , I had determined there was a no spark condition. I came to this conclusion after removing a spark plug from each cylinder bank and grounding it and cranking the engine. No spark. Not even a weak spark. Also the spark plugs are relatively new with about 30 hours on them. Also , it would not fire on ether. That sent me delving into all possibilities for a no spark condition. When I ran out of ideas and the boat forums were not providing any answers , I began researching car forums. A lot of very technical diagnosis videos on youtube. Shrodingers Box was particularity helpful.
It got me thinking of the veracity of my spark check. I bought a spark tester and put it on the previously dead spark plug cylinders and low and behold...spark. Long story short, there were 5 dead spark plugs. How that is even remotely possible , I do not know. The engine ran perfectly when put away for winter and somehow those spark plugs decided to fail just sitting there. I feel somewhat foolish for spending the last 3 weeks killing myself chasing down this problem and it turning out to be the simple spark plug but the evidence really wasn't leading me to mass spark plug suicide.
Anyway , I bought 8 AC 41-983 plugs , installed them , and the engine fired right up. It quit after 30 seconds and I did a fuel rail bleed and all was well. By the way , I have read that these engines are fussy with plugs and to only use the AC plugs. That was what I did have installed before the problem.
So there you have it. I will be taking the boat out hopefully tomorrow to run her through the paces and confirm this nightmare is over. Thanks to all for the help/suggestions and I hope this thread may help someone else in the future.
 
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So glad to read this tonight! Prayers for a good run tomorrow!

Update...Final update , I hope...

The port engine is running. Quite nicely. After spending all Sunday doing a pin out and not finding any shorts or bad grounds or broken wires , I was feeling defeated.
If you remember , I had determined there was a no spark condition. I came to this conclusion after removing a spark plug from each cylinder bank and grounding it and cranking the engine. No spark. Not even a weak spark. Also the spark plugs are relatively new with about 30 hours on them. Also , it would not fire on ether. That sent me delving into all possibilities for a no spark condition. When I ran out of ideas and the boat forums were not providing any answers , I began researching car forums. A lot of very technical diagnosis videos on youtube. Shrodingers Box was particularity helpful.
It got me thinking of the veracity of my spark check. I bought a spark tester and put it on the previously dead spark plug cylinders and low and behold...spark. Long story short, there were 5 dead spark plugs. How that is even remotely possible , I do not know. The engine ran perfectly when put away for winter and somehow those spark plugs decided to fail just sitting there. I feel somewhat foolish for spending the last 3 weeks killing myself chasing down this problem and it turning out to be the simple spark plug but the evidence really wasn't leading me to mass spark plug suicide.
Anyway , I bought 8 AC 41-983 plugs , installed them , and the engine fired right up. It quit after 30 seconds and I did a fuel rail bleed and all was well. By the way , I have read that these engines are fussy with plugs and to only use the AC plugs. That was what I did have installed before the problem.
So there you have it. I will be taking the boat out hopefully tomorrow to run her through the paces and confirm this nightmare is over. Thanks to all for the help/suggestions and I hope this thread may help someone else in the future.
 
Update...Final update , I hope...

The port engine is running. Quite nicely. After spending all Sunday doing a pin out and not finding any shorts or bad grounds or broken wires , I was feeling defeated.
If you remember , I had determined there was a no spark condition. I came to this conclusion after removing a spark plug from each cylinder bank and grounding it and cranking the engine. No spark. Not even a weak spark. Also the spark plugs are relatively new with about 30 hours on them. Also , it would not fire on ether. That sent me delving into all possibilities for a no spark condition. When I ran out of ideas and the boat forums were not providing any answers , I began researching car forums. A lot of very technical diagnosis videos on youtube. Shrodingers Box was particularity helpful.
It got me thinking of the veracity of my spark check. I bought a spark tester and put it on the previously dead spark plug cylinders and low and behold...spark. Long story short, there were 5 dead spark plugs. How that is even remotely possible , I do not know. The engine ran perfectly when put away for winter and somehow those spark plugs decided to fail just sitting there. I feel somewhat foolish for spending the last 3 weeks killing myself chasing down this problem and it turning out to be the simple spark plug but the evidence really wasn't leading me to mass spark plug suicide.
Anyway , I bought 8 AC 41-983 plugs , installed them , and the engine fired right up. It quit after 30 seconds and I did a fuel rail bleed and all was well. By the way , I have read that these engines are fussy with plugs and to only use the AC plugs. That was what I did have installed before the problem.
So there you have it. I will be taking the boat out hopefully tomorrow to run her through the paces and confirm this nightmare is over. Thanks to all for the help/suggestions and I hope this thread may help someone else in the future.

Glad to hear you solved the issue. Never heard of mass spark plug suicide either. I had one go, didn't really notice it other than WOT dropped a couple of hundred RPM, but then a second one went and it was a noticeable drop in power compared to the other engine. Never 5 at one time. Strange that you tested both engines for spark the same way and got a strong spark off the stb, but no spark on the port...
 
More often than not it's something ridiculously simple. On the bright side, I suspect you learned a ton you didn't know about these engines. Bet it felt good to get out there and run it! Cheers.
 
What a sigh of relief. I've been following along as I went through some 8.1 hell myself a few seasons ago. That also turned out to be plug related. So frustrating and yet such a relief at the same time.

But you can always look at the bright side that you saved 3 weeks of gas usage. :)

Now go enjoy your summer.
 
My question is; are these spark plugs being made over seas now possibly in china as the reason for the many failures?
 
John the 8.1 guru that runs Boats Unlimited in Texas says the first thing he does is puts 8 spark plug testers on all plugs. Good idea since you also have 8 coils
 
timeflys...I used to fly an ST-27 in the 80's. The good old Saunders , now residing in museums...
 
scoflaw...still can hardly believe that was the problem but hopefully this will be incentive for anyone else to check/change the plugs first regardless of age and possibly save themselves a lot of work/frustration. Thanks for all your help.
 
atrick...I bought the bum plugs at O'Reilly's and not the internet so you would think they were not knockoffs.
 

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