2003 Nautique Excal. will Turn Over/Not Fire - Fouled #3 Plug - Compression is Good

[dkimball]

While pulling a flyer of the dock yesterday my boat sputtered and cut out and would not restart. Fuel pumps prime, spark is good and all but one of the plugs were nice and clean. I swapped the dirty plug with a clean one and it fouled that plug as well. I was able to get it to fire up with the plug out running on 7 cylinders. I have it scheduled to get looked out but they are a couple weeks out so in the mean time I am going to replace the plugs, cap and rotor to see if that helps. There was a little corrosion on the cap but I wouldn't think it would cause it to cut out and die. What are your thoughts? Do you think it could be a stuck lifter? Bad valve? I believe fuel is spraying into the cylinder but it just isn't firing for some reason. There does appear to be spark.

[NautiqueJeff]

Sounds like a bad spark plug wire, or possibly a failed rotor. Hopefully it isn't anything more than that.

[dkimball]

Wouldn't you think a bad rotor would cause more than just one cylinder not to fire? The wires and plugs are 3 years old going into our 4th summer. I thought if the rotor was bad it would still run but would just run rough. Could be a bad wire I was going to swap a couple out and see.

[jpwhit]

If the distributor cap and rotor haven't been replaced recently. You should start there. The GM Vortec 5.7 these marine engines are based on, are notorious for the cap and rotor to fail. The distributor is also notorious for the distributor cap screw tabs to crack and not hold the cap down tight. If that's the case, here is a simple fix.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[dkimball]

Just wanted to give an update. After dismantling way more of the engine that we should have/probably needed to I believe the culprit ended up being the cap and rotor. While waiting for parts we took the valve cover off and everything looked good so we pulled the fuel rail and swapped the Blogs injector with the Home injector. Put it back together and it still wouldn't fire but after a small backfire it did seem to crank over a lot better and didn't have any "dead spots". Cap and rotor finally showed up so we put them in and she fired up. I am just going to tell myself that we "knocked the rust off" by checking everything out and that in combination with the cap and rotor is what did it. I did change the plugs out as well as we fouled them up pretty good trying to trouble shoot.

[shag]

I had a similar issue a while back and it was the cap. I actually got 2 bad caps in a row... They had hairline cracks and it was enough to cause a miss... It was PITA diagnosing it... Especially after still having the issue with the first new replacement..