Seadoo 1996 GSX 781 wont turn over with plugs in

[Andrewdinsdale]

Hi guys,

I'm new to this forum and Seadoo PWCs.

I have just bought my first ever seadoo ski, a 1996 GSX. (781cc)

Its been converted to pre-mix, had an engine rebuild roughly 30 hours ago but been stood for 2 years since.

It has a good spark and compression but when trying to turn it over with both plugs in nothing happens.

I've just replaced the starter solenoid as it was bad and had it turn over the odd time with both plugs in but most of the time nothing happens.

I read somewhere on here that when standing oil can leak into lower crank and sort of hydro lock it up and you need to clear the oil before trying to start it but nothing seems to work.

I've also had the starter off and apart, cleaned it all up and back together, brand new battery and cleaned up all the battery cables.

Any help appreciated I'm at a bit of a loss with it.

Andrew

 

[mikidymac]

When cranking it with the plugs out does any oil come out of the plug holes?

If there is no oil then it isn't that.

Typically when you have your issue it is a bad battery. Make sure you have it load tested. Then I would suspect the starter and finally the cables.

 

[Andrewdinsdale]

When cranking it with the plugs out does any oil come out of the plug holes?

If there is no oil then it isn't that.

Typically when you have your issue it is a bad battery. Make sure you have it load tested. Then I would suspect the starter and finally the cables.

Hi,

Thanks for a quick reply!

Its a brand new battery (not even 48 hours old yet) so id hope it was ok. Im currently just re charging the battery incase it is as simple as that but I have tried another battery from the car with jump leads (yes i removed the battery first) and it was the same fault. The starter looked good when I stripped it down. Maybe I need some new brushes / or cables?

With regards to the oil, when i first bought the ski and took the plugs out yes I got lots of oil coming from the front cylinder, then thats slowly died down to almost none now so i don't know if thats the issue or not.

Andrew

 

[mikidymac]

I would suggest new brushes in the starter. Very typical to be worn.

If it is a Walmart battery I have seen them bad out of the box.

 

[Cliff787]

Andrew,

When you say, "When trying to turn it over. It does nothing."

Do you mean: "nothing" as in it doesn't start or "nothing "as in the motor doesn't turn at all or "nothing"as in the motor cranks very slowly?

How many total hours on the ski?

Was it just the top end that was just rebuilt or was the crank also rebuilt along with the top end?

 

[Andrewdinsdale]

I would suggest new brushes in the starter. Very typical to be worn.

If it is a Walmart battery I have seen them bad out of the box.

Turned out to be the cables, new cables and turns over perfectly every time. New problem- won't start. I have a spark (Not sure if its strong enough?) guess ill try some new carb diaphragms before anything else as these ones look ancient.

Cheers for your help.

 

[Andrewdinsdale]

Andrew,

When you say, "When trying to turn it over. It does nothing."

Do you mean: "nothing" as in it doesn't start or "nothing "as in the motor doesn't turn at all or "nothing"as in the motor cranks very slowly?

How many total hours on the ski?

Was it just the top end that was just rebuilt or was the crank also rebuilt along with the top end?

Hi when I say nothing i mean the starter engages but doesn't turn over, sorry I should have explained properly.

I just put some new starter cables on that I made up and seems to be OK now but won't start, just replied to another comment on my problem.

The ski has 158hours on the clock. It was rebuilt fully with new liners, pistons etc.

Cheers.

 

[Cliff787]

1.) All stock motor?

2.) Have the carbs been recently rebuilt?

3.) New needle & seats(valves)?

4.) Fuel lines replaced?

Your ski looks great! I have the exact same year & model and have owned mine since brand new way back in Aug. 1996!

The GSX is a true 2 seater in my opinion as it is wide and long enough(stability wise) to carry an extra person on it. It can still tip over in deep water re-boarding situations. But much easier than re-boarding a '96 XP(I also own a '98 SPX since new) or similar model since it has a wider platform in the rear to get back onto it.

Very fun ski! Has the 15 gallon fuel tank. So cruising time can be "extended" over the 9 gallon tank of the XP/SPX models.

 

[Andrewdinsdale]

1.) All stock motor?

2.) Have the carbs been recently rebuilt?

3.) New needle & seats(valves)?

4.) Fuel lines replaced?

Your ski looks great! I have the exact same year & model and have owned mine since brand new way back in Aug. 1996!

The GSX is a true 2 seater in my opinion as it is wide and long enough(stability wise) to carry an extra person on it. It can still tip over in deep water re-boarding situations. But much easier than re-boarding a '96 XP(I also own a '98 SPX since new) or similar model since it has a wider platform in the rear to get back onto it.

Very fun ski! Has the 15 gallon fuel tank. So cruising time can be "extended" over the 9 gallon tank of the XP/SPX models.

Hi again!

They are a great looking ski, my friend has a 99 GSX ltd here in the UK and that was my inspiration on buying this one. I wanted to get one all running but I couldn't find any in good condition running so I had to settle for this one in fantastic condition just not running.

1) All stock motor, the only mod I can see is straight through exhaust

2) I took the carbs off and apart yesterday, the diaphragms looked old but none were torn or damaged so I cleaned them up and put them back as they were. (Just ordered a new set of diaphragms for both carbs, tricky to get parts here in the UK). The jets in the carbs looked like new.

3) Seats and Valves looked fine. They seem to shut off as they should.

4) Fuel lines are not genuine ones (I don't think) but all look good. Drained 40Litres of old fuel out of the tank and put in a fresh 20Litres premixed today.

Now the engine turns over, as it should, will fire very very occasionally but won't start. I'm guessing this is just a fuel problem. I need to do another compression check now its turning over as it should but when I checked initially they were great.

Any ideas? Cheers

 

[mikidymac]

Mix up a little premix and pour a little in each carb. See if it pops off and runs.

 

[Andrewdinsdale]

Mix up a little premix and pour a little in each carb. See if it pops off and runs.

Thanks, I'll give that a go in the morning. Neighbours won't be too happy if I do that now, its almost 9pm here.

I'll keep you updated.

 

[Cliff787]

Try what Mikidmac suggested.

Also check the common Ground screw with the Phillips head in the rear black box where all the black wires (about 7 of them) with the terminal ring connectors Ground to. That common Grounding point comes loose and will cause headaches because the Ground connection there isn't a solid connection anymore. It tends to break internally and the Grounding screw wiggles or becomes loose.

Did you also connect the short Grounding wire that comes from the top of the rear electrical black box to the Negative(-) battery connection?

The motor will never fire if this wire isn't connected.

 

[Andrewdinsdale]

Try what Mikidmac suggested.

Also check the common Ground screw with the Phillips head in the rear black box where all the black wires (about 7 of them) with the terminal ring connectors Ground to. That common Grounding point comes loose and will cause headaches because the Ground connection there isn't a solid connection anymore. It tends to break internally and the Grounding screw wiggles or becomes loose.

Did you also connect the short Grounding wire that comes from the top of the rear electrical black box to the Negative(-) battery connection?

The motor will never fire if this wire isn't connected.

The wires in the rear E-box seem good, all connected, clean and the screw is tight. I did a continuity check between that screw and the neg on the battery and all seems fine.

The Grounding wire which comes out of the rear E-box is connected yes.

I tried pouring a few squirts of fuel into the carbs and still nothing.

I attached two spark testers to my plugs/leads and I'm getting a spark, fuels going in (one way or another) and theres compression. I don't really know what else I can check.

I'm going to chuck in some new plugs tomorrow to be sure its not them.

Thanks for the help.

 

[Cliff787]

Spark plugs should be NGK BR8ES; gap is 0.020" - 0.024"

Did you clean the passageways on the carbs when you took them apart using a thin wire or compressed air?

We're the Pilot and Main jet openings clean?

 

[Cliff787]

Spark plugs should be NGK BR8ES; gap is 0.020" - 0.024"

Did you clean the passageways on the carbs when you took them apart using a thin wire or compressed air?

We're the Pilot and Main jet openings clean?

 

[Andrewdinsdale]

Spark plugs should be NGK BR8ES; gap is 0.020" - 0.024"

Did you clean the passageways on the carbs when you took them apart using a thin wire or compressed air?

We're the Pilot and Main jet openings clean?

Great I'll pick two of those up this morning.

Both the pilot jet and main jet openings were clean, but i only blew the passageways out with carb cleaner as thats all I have at home, no compressed air unfortunately. If the plugs don't work I'll re-clean the carbs and poke those out with wire. Is that the three tiny holes and one slightly larger hole in the throat of the carb?

Thanks

 

[Andrewdinsdale]

Ok so the latest;

Put two fresh spark plugs in this morning, no difference.

Cut back the HT leads slightly and screw the caps on fresh, no difference.

Found the earth wire feeding the rear E-box was actually very corroded so I replaced it, no difference.

Found the earth wire feeding the coil from the rear E-box earth post was very corroded so I replaced it, no difference.

Checked all connections/multiplugs relating to the ignition coil etc and nothing was corroded/rotten.

I'm thinking I've got a week spark issue as fuel is definitely getting to the cylinders as the plugs are wet overtime I turn it over.

Are there voltage/resistance checks I can do for the coil. I might need a new one.

Cheers

 

[Andrewdinsdale]

Another test done,

Checked my battery voltage whilst cranking and I'm getting 11.7volts when cranking then about 12.7 when I stop. Does that sound about right?

I've checked all the earths I can see, added another battery ground to be sure.

I can't get it to even fire now, have I got some serious electrical problems?

 

[jhjesse]

Trigger coil inside the stator could be going out. Mounting brackets on early models were prone to crack and break.
I would pull the stator cover and check. Will need to place a board under the engine for support.

 

[Andrewdinsdale]

Trigger coil inside the stator could be going out. Mounting brackets on early models were prone to crack and break.
I would pull the stator cover and check. Will need to place a board under the engine for support.

Hi there thanks for the help!

I'll check that as soon as I'm home.

Last time I turned the engine over it did spit out fuel of the front of the carbs (I took he flame arrestor off to put some fuel straight in the carbs) I'm sure it's not it but I read something about the rotary valve gone?

Or maybe a flywheel key gone? It doesn't even back fire though.

Thanks

 

[Cliff787]

A sheered (broken off) woodruff key will cause a "no start" situation.

The rotary valve is made of metal(I don't know what type of metal) and is very durable. Timing the rotary valve (159* stock timing)requires a rotary degree wheel.

The rotary valve can be flipped over to get the valve as close to the correct timing(+\-5*) as possible. The valve can be off by as much as a half a tooth on the rotary valve shaft gear that the rotary valve is attached to.

 

[jhjesse]

Hi there thanks for the help!

I'll check that as soon as I'm home.

Last time I turned the engine over it did spit out fuel of the front of the carbs (I took he flame arrestor off to put some fuel straight in the carbs) I'm sure it's not it but I read something about the rotary valve gone?

Or maybe a flywheel key gone? It doesn't even back fire though.

Thanks

I understood it to be weak or no spark. If so then could be the coil or the trigger coil (pick up coil).
Back firing is something else. Is it back firing?

 

[Andrewdinsdale]

I understood it to be weak or no spark. If so then could be the coil or the trigger coil (pick up coil).
Back firing is something else. Is it back firing?

It did back fire once on attempting to start it. I think weak spark is my guess too but not sure on how to get at the trigger coil yet.

 

[Andrewdinsdale]

A sheered (broken off) woodruff key will cause a "no start" situation.

The rotary valve is made of metal(I don't know what type of metal) and is very durable. Timing the rotary valve (159* stock timing)requires a rotary degree wheel.

The rotary valve can be flipped over to get the valve as close to the correct timing(+\-5*) as possible. The valve can be off by as much as a half a tooth on the rotary valve shaft gear that the rotary valve is attached to.

From my experience it sounds like a flywheel key to me but I don't want to pull the engine out for it. Can it be done in situ?

Am I right in saying I should leave the rotary valve well alone?

 

[Andrewdinsdale]

Ok I'm getting very frustrated with it now.

I took the carbs off just to check the rotary valve was spinning (I read they can lose drive if the teeth wear) this all seems fine.

I don't particularly want to take the flywheel off and check the key and trigger coil as I'm hoping its something more simple.

Anything else I can check before going ahead ?