SportJet 90 - no spark

[PCNETT]

I have a 94 Bayliner Reflex with a SportJet 90 (Mercury/Force). I pulled all the plugs and did a compression test. The results were not good 120 110 and 90. After I did the test the boat would not start or even fire. I did a voltage check on the low voltage side of the coils while turning over the engine and the meter didn't move. I noticed in a forum response that it was recommended to ground a plug wire if it was going to be removed while running the engine. Failure to do so could damage the ignition system.I was turning the engine over but not actually running it. Could what I did have damaged something? If yes what is the most likely component? I don't see anything red under the flywheel so I suspect I have the old style stator. Should I be able to see the stator without removing the flywheel?<br /><br />I have ordered the service manual and it should be here this week. I sure wish I would have waited for it before starting any work.

 

[kenimpzoom]

Re: SportJet 90 - no spark

Hi, For more information, click on my homepage (icon above). It has detailed ignition diagnostics that will tell you what has failed.<br /><br />Yes, you can hurt the ignition by cranking the engine without the plug wires grounded. It most likely fried the ignition box.<br /><br />I dont think you can see the stator under the flywheel. You can tell if you have the red stator if you have the red stator adaptor. My homepage explains what it looks like.<br /><br />The compression on the top cylinder will always be 10-15 points lower.<br /><br />Why did you do a compression check, was the engine running poorly?<br /><br />Ken

 

[PCNETT]

Re: SportJet 90 - no spark

I bought the boat used and it has always been a poor performer. Lately it has gotten worse with longer plane times and top speed with a single passenger of less than 25mph. Prior to the compression check, it started fine and ran smoothly. After studying some of the other forum items I was suspecting a leaky rider plate gasket. Someone suggested covering the seam between the plate and the hull with metal duct tape. If performance improved the gasket was leaking. If it didn't the problem is somewhere else. I put the tape on but decided to do the compression check before putting it in the water. Unfortunatly due to the ignition box problem I didn't get a chance to do the gasket test. The impeller clearance is approximately 32-34 thousands. I took it in recently to have the carbs cleaned but I don't know how through of a job they did.<br /><br />Thanks for your response. I will check out the web site.

 

[kenimpzoom]

Re: SportJet 90 - no spark

If it was taking long to plane and low top speed, it may have been firing on only two cylinders.<br /><br />The metal tape is a good idea.<br /><br />Ken