94 SPX Idle / revving problem

[anderst6]

I just rebuilt both carburetors, replaced all fuel lines, and cleaned the fuel filter. In addition, I had to reset the timing - because I had to remove the oil pump to replace a gasket - when I did the rotary valve fell off. Prior to rebuilding the carburetors, the motor would idle for about ten seconds then start revving on its own. After the rebuild, the motor still idles for about ten seconds then starts over-revving. Does anyone have any ideas? Also, I had to replace a small oil line to the rear intake – how do you re-prime the oil pump?

[WATERCRAFTSERVICES]

Re: 94 SPX Idle / revving problem

You have a lean idle condition. First off be sure the low speed adjusters are set properly. If all checks out then you have an air leak somewhere. Could be something as simple as a bad gasket,bad intake seal or a bad crank seal. A case pressure test will tell you. The pump will reprime that line by itself. That line is on the positive pressure side of the pump. Just be sure to add some oil to that cylinder thriugh the carb for a minute or two. This will give the oil time to go through the line and reach the injector inside the manifold. Or you can just crank the motor without starting it until oil appears at the end of the line.

[anderst6]

Re: 94 SPX Idle / revving problem

Thanks for the quick reply and information - how do you do a case pressure test to fine the air leak?

[WATERCRAFTSERVICES]

Re: 94 SPX Idle / revving problem

You can build an inexpensive tester for your needs. Go to the search section on the forums start page and type in case pressure test. There are alot of threads there you can read and get familiar with the process of case pressure testing. But start with the simple things first. Gaskets and seals. Then use a process of elemination to locate the problem.

[anderst6]

Re: 94 SPX Idle / revving problem

I have synched the carbs according to Mikuni documentation. Spent the better part of today rechecking all connections and bolts. Started the engine and still revs rather quick. Scared to leave it running long enough to try verifying the oil pump alignment, because the engine revs so high so quick - probably close to max RPMS. I have not pressure tested the engine yet - but may have too? Any other help or ideas will be much appreciated.

[Bill O'Neal1]

Re: 94 SPX Idle / revving problem

Try loosening up the throttle cable, it is easy to get it too tight.

Back off the idle screw adjuster.

Turn the low speed adjusters out a bit to richen the mixture.

If none of that works, look for an air leak.

To prime an oil pump, open the bleeder screw on the pump and let some oil run out of it.

[anderst6]

Re: 94 SPX Idle / revving problem

Bill, thanks for the help - turns out the oil pump is not working properly. After checking connections, backing off the idle the problem remained. (I had already premixed fuel in the main tank with seadoo oil - but it had not reached the carbs at this point.) So I disconnected the crossover fuel line between the carbs (clear fuel at this point - no oil in gas that came out from premix), disconnected the rear cylinder spark plug wire, and moved the return fuel line to the front carb. Started the engine - ran like a champ. Reconnected rear carb - now the fuel contained oil from the premix. Started with both cylinders. set the idle - and runs great. Of course, the ultimate test is on the lake - sometime in the near future. However, it appears the oil pump was not working to specification, causing a lean condition. I will be installing a block off kit in the oil pump.:)

[dank]

Re: 94 SPX Idle / revving problem

A non working oil pump will not cause a lean "fuel starvation" running condition just a lubrication failure of the pistons/rings. Your problem may still be there or the engine was not run long enough to prime all the lines and carbs causing the lean condition?