1998 GTX RFI Fouls Plugs

[Hankr]

I have a new engine from SBT installed by a qualified Mechanic. He turned the ski over to me to follow the break in procedure. I have followed the procedure to the letter. Im on my first tank of fuel in the process where you run the engine up to 90 % power. After running perfectly for about an hour it fouled both plugs. I know the instruction call for changing the plugs after the break in process but I have a long way to go to get to that point. The Mechanic that installed the engine will return to see whats going on (but it wont be for a while) i was hoping to get some quick ideas so I might use the jet ski. Any ideas what might be happening, or suggestions. The plugs are black and have heavy deposits on them.

[Technical Support]

Re: 1998 GTX RFI Fouls Plugs

Most likely it simply needs new plugs. The extra oil fouls them early especially on smaller displacement models or if you really baby it, or have long idle zones.

Just change the plugs when it happens.

[Hankr]

Re: 1998 GTX RFI Fouls Plugs

Thanks for the input, what do you mean "the extra oil" . I did not think extra oil was used on the break in on a RFI engine. I will give your suggestion a try and see what happens. I really appreciate your response. I sure hope that im not changing plugs every hour like i did on this ride. Its not so easy when it happens and your away from shore and the water is choppy.

[Technical Support]

Re: 1998 GTX RFI Fouls Plugs

Sorry, I missed the RFI in your title! Take a look in your fuel filter and see if it's straight fuel or not. If they added oil (many do) drain the system.

[Hankr]

Re: 1998 GTX RFI Fouls Plugs

Thanks for the reply, I called the mechanic and he told me that he did not add any oil to the fuel. He was concerned that the solution is more than just changing the plugs because of the circumstances of how the problem occurred although were giving the plugs a try. The sled was being run around 4K rpm for about an hour and running fine, then brought down to an idle and then i immediately tried to accelerate and it would not get on plane. The most i could get out of it was about 2500 rpms. I pulled one plug out in the open water and replaced it. The plug that came out had a lot of heavy black deposits between the center electrode and side of the plug. Once the plug was changed the sled ran fine at least for another half hour when i again slowed down and it did the same thing again. I did not have any more plugs to change so i limped back to the dock and called the mechanic for help.
The mechanic called SBT for input and they felt that there were a couple of other possibilities, focused around the fuel injectors. The injectors might be faulty or the voltage regulator providing bad voltage to the injector system . The voltage regulator is new so thats probably not a cause.
What do you think ? Thanks Hank

[Technical Support]

Re: 1998 GTX RFI Fouls Plugs

Faulty injectors is a common problem, they are very crude for the job. It's also possible it's simply being operated outside the norm. Staying at 4k for an hour really loads them up. Break-in specifically says to vary your throttle position for this reason.

[Hankr]

Re: 1998 GTX RFI Fouls Plugs

THanks for the input, I was not vary precise when i talked about running at 4K for an hour, I followed the break in procedure and varied the throttle but kept it much higher than idle yet no more than 90%. Was just trying to get the idea across that i was not at idle for a long time. I will let you know what we find out, and again thanks for the quick replys. Hank

[Hankr]

Re: 1998 GTX RFI Fouls Plugs

Well heres the latest status. The mechanic removed the injectors and had them sent out to be patterned. They were cleaned and returned as good. The injectors were reinstalled along with new plugs. After running a tank of fuel the engine again started to miss on a cylnder then ran on one cylnder only. I changed the plugs and it again ran fine. Any new Ideas ?

Thanks Hank

[Bill O'Neal2]

Re: 1998 GTX RFI Fouls Plugs

It probably needs a new coil or sparkplug wires and sparkplug connectors.