scoflaw
Well-Known Member
- Aug 10, 2011
- 6,395
- Boat Info
- 1999 Powerquest legend 260 sx 502 mag
2005 Baja 242 islander 496
- Engines
- 502 mpi Bravo 1
496 mag B1
Track voltage on the r/y wire going to and leaving the relay on top of engine.
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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.