Seadoo GSX needs new spark plugs every hour??

[donaldjboyer]

Hi all,

Seadoo GSX 1997
110 hours

I have had an issue over the last few months where I'll install brand new spark plugs in this machine and it'll run fine for approx 1 hour and then start running rougher and rougher over a few minutes until it'll barely run. The only remedy is to install brand new spark plugs again (which only last for an hour). And in a recent run, the 'check engine' light came on the dash briefly also.

I have cleaned the carbs, fresh fuel, new battery (fully charged). When I have checked the voltage at the battery (while running on the garden hose) the voltage jumped around quite a lot, but the display refresh on the digital multimeter was slow which made it difficult to see what was going on.

I am thinking the voltage regulator might be at fault, but could you please help me by suggesting what I should look at diagnosing? (trim spark plug lead ends? check negative cable from battery to engine etc).

Thanks in advance,

Donald.

 

[mikidymac]

What do the plugs look like? Oil fouled?

 

[donaldjboyer]

Not particularly, I'll try find a photo now

 

[donaldjboyer]

Sparkplugs

 

[mikidymac]

Plugs look rich but should have no issues running much longer. The plugs are not the issue.
I would check compression first. Then battery voltage with the engine off, idling and at 4,000 rpm and report back.

 

[donaldjboyer]

Plugs look rich but should have no issues running much longer. The plugs are not the issue.
I would check compression first. Then battery voltage with the engine off, idling and at 4,000 rpm and report back.

I completed the voltage tests as per above. No matter what the rpm, the voltage varies between 13.5 and less than 1 volt. See the short video for an explanation.

Any ideas please?

Donald.

 

[donaldjboyer]

I completed the voltage tests as per above. No matter what the rpm, the voltage varies between 13.5 and less than 1 volt. See the short video for an explanation.

Any ideas please?

Donald.

Anyone please?

 

[GGuillot]

Anyone please?

You're testing with the DMM connected at the batt? with it jumping all over the place I'd double check grounds, I don't think it should be jumping erratically like that. Good continuity test between the engine and batt neg?