1998 Sea Doo GTX Limited - fouling plugs and pudding in the hull.


Hello again!

When I bought this machine, I tested and got compression in the 150-160 lbs range and saw 340 hours on the clock. I had new fuel and oil lines done, reterminated plug wires, new plugs. New sleeve on the impeller.

Trail of bread crumbs- spare spark plugs in the glove box.

It fouls plugs about every one to two hours. It starts best cold if you hold the choke out, go full throttle (with your knee) and press start.

There is also melted ice cream looking oil/ water pudding in the hull. Not much- maybe two cups total. But WTH?

I have overfilled the oil tank twice. That’s messy.

Then I find that I’m having to run about 3/4 tank of oil for every full tank of fuel.

is that normal? It does smoke but not a lot. Barely a haze behind it.

Oil pump rebuild? Carb rebuild? Where is the oil pump? Burn it? Sell it?

Any advice is appreciated.
The oil pump might be set too high. The pump is on the front of the engine under the exhaust. Check the manual the setting is in it somewhere
Wow,, 350 hours is near the limit,
I would’vecheck compression to start,, poor psi will foul a plug.
Also test out the rectifier and load test the battery. Many many years ago,, I chased a “ plug fouling” problem,,, finally changed out battery, bingo!!!
he said he has 150-160 compression but im pretty sure that the 98 gtx has a 951 that should be 130 compression
Make sure your oil pump is hooked up to the cable. If its become disconnected it will run oil pump wide open. Verify the alignment marks are lined up on the oil pump also.
The compression guage you are using is probably off or cheap, Normal is 130 to 150 for a engine in good shape. Mine has 40 plus hours on it , rebuilt engine, and it is in the low 130s. Might want to see if you can get a reliable guage and recheck. With 340 hr on the dash you , if your compression turns out to be in the 120 to 130s then you probably have a rebuilt motor in it as well, not sure you will be able to tell how many hrs is on that motors.
With the oil issue, I would imagine your oil system is wide open, Which is what happens if anything goes wrong with the cable going to the system, it protects the engine from burning up. I have run two tanks on my machine and used about 1/3 a tank, at best. There is a cable running to the carbs, which sync the carbs and oil system, see if it is there. That is possibly what is fouling your plugs. You could also have a hole in your oil hoses, inspect the little clear hoses (they could be painted over too) going from the oil system to the engine block. Look for leaks. What color/brand is the oil you are using? Are you sure it is the right stuff? The weird thing is you should be smoking a lot if the oil system is wide open.

I like my ski, its fun and fast. Once you get the kinks worked out , they are pretty reliable.
It’s the red, sea doo brand full synthetic oil.

I’ll look for that cable, etc. in a couple days.

1998 GTX Limited is the 951 engine, not the 787 and smaller.
Perfect compression on his 1998 951 is 130 psi, not 150.

You are using way too much oil per fuel and is the cause of your fouled plugs. You should be getting about 4-5 tanks of fuel to a tank of oil at worst.