SportJet 90 = Dead again

A

aucklajc

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Feb 1, 2005
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I have a 1994 Sea Rayder with the infamous SportJet 90. It has given me the usual problems over the years, but this one has me stumped.

I replaced the entire ignition system and electronics two years ago with the upgrade package that eliminated most of the mystery boxes. It ran fine for about 10 hours, then it died on me. I was running at high speed, it started to hesitate, like it used to, it coughed and sputtered, then died. It has not run since.

I have checked the spark on each plug - OK. There is fuel to each cylinder. I drained the fuel tank and put in fresh gas (I troll mostly, so this engine does not get much use - less than 100 hours). I removed the carbs and checked the reed valves - OK. I removed the flywheel to be sure that the key hadn't slipped or broken - OK.

I did notice a steady stream of fuel coming out of the front of each carb when I cranked it with the backfire arrester cover off. It is certainly getting plenty of gas. Could the carb vents be blocked? I do have a residual of fuel on the plugs when I remove them, so I assume it should at least try to start.

So, there is spark, there is fuel, but I can't even get it to spit or cough -nothing. I do not have a manual for it, so I don't know what voltages or resistances to check.

Where is a good place to get a repair manual? Any suggestions on what I should be looking for to get it going again?

I thank you guys ahead of time for your help.
Jim
 
Texasmark

Texasmark

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Dec 20, 2005
Messages
14,786
Re: SportJet 90 = Dead again

I only had one engine die at WOT and it locked up tight. It was a Rude 3 cyl 70 hp and had a tstat, but no warning buzzer......before the days of telling you about problems. The stat froze closed and the engine just overheated and seized. Didn't know it could do it, but the prop froze and you won't believe how fast your boat will stop when your prop stops driving and just locks up tight.....nearly threw me out of the boat.

I am looking at the service manual for the '94 90 jet and it shows to have both oil and over temp sensors and a warning module....only good if they make the horn blow.

Not a real complicated system for engine spark. Has two coil systems under the flywheel for triggers and battery recharge voltage, a Switch box that gets inputs from these two coil assy's and outputs to 3 separate ignition coils. But you have plenty of that....guess it is of adequate level.

Only thing that might be a problem is a 20 amp inline fuse that goes to the remote connector leading to the control box but with what you said that shouldn't be the problem.

There is an enrichment valve that supplies fuel to the carbs for starting. You can disconnect the output hose from it (going to the carbs) and insure that it is closed (no fuel out) unless you turn the key to on and push in on it.

Unless all 3 carbs are suffering from varnish due to lack of use (good cleaning required and insure float is correctly set), the fuel enrichment is a common element and could be causing fuel to exit the carb when you crank it.....assuming you saw excess fuel coming from all 3 carbs.

My manual came from Merc....got it with my boat from previous owner. Guess you can go to www merc and order one like other merc parts.

Best I can do.

Mark
 
arboldt

arboldt

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Death_2u

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Dec 21, 2009
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Re: SportJet 90 = Dead again

Do you guys know where i can find a wiring diagram for the boat side, im try to troubleshoot a starting problem, that i hope it is, at the ignition key and safety lanyard. any help will do. thank you!

Manuel
 
Texasmark

Texasmark

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Dec 20, 2005
Messages
14,786
Re: SportJet 90 = Dead again

Death_2u said:
Do you guys know where i can find a wiring diagram for the boat side, im try to troubleshoot a starting problem, that i hope it is, at the ignition key and safety lanyard. any help will do. thank you!

Manuel
Click to expand...

Submit this as a separate post and you will have a better chance of getting your question answered. But in the meantime a service manual covering your engine will have what you want....may sell them on this site; otherwise go to Merc (www) Published diagrams are usually copywrited which means one cannot copy one and send it to you.

Mark
 
C

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: SportJet 90 = Dead again

You have to start with the absolute BASICS to troubleshoot your problem.

Check compression on ALL cyl's

Check spark QUALITY with a 7/16 inch gap on ALL cyl's

IF, and you notice that is in caps also, IF it passes BOTH those tests, only then do you get to move on to the fuel system.

Even the slightest of ground/fault in the ignition switch OR the lanyard switch and the ignition system will NOT provide enough spark to run, yet it may make enough spark for you to see just holding a plug wire very near the engine block. That's not good enough, it MUST be hot enough to brightly arc across that 7/16 inch gap.

If it fails, disconnect the black wire with the thin yellow trace from between the ignition module and the engine wiring harness and retest spark. If it NOW passes, then your problem is a slight ground of that black/yellow wire, a bad ignition switch, lanyard switch, or a short somewhere.
 
C

crankin4bass

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Dec 20, 2009
Messages
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Re: SportJet 90 = Dead again

I have had water travel back through my vent hose when coming to a stop thus putting water in the fuel tank. If you suspect this take a fuel sample in a glass jar and check it in few hours to see if there is any separation. Its worked for me in cars and boats and you can also pour some out and see how flameable it is.
PS: I am looking at purchasing a boat with a sportjet, what kind of problems plague these motors. How much is the electronics upgrade package and where do you you get it? Thanks
 
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