96 XP Blowing Fuel when plugs are out

[Tesler32]

I have a 96 XP 787 was running great just last week now it won't start. When I pull the plugs they wet with fuel. When I crank it over its blowing out fuel from both cylinders out the top of the engine. Does anyone know what the issue could be. Should I just get a carb rebuild kit and go through them or is there something specific in the carbs that can cause this.

This boat is stock so 38mm dual carbs. No engine mods had top end done a couple seasons ago.

[nmpeter]

sounds to me that there is no spark. Unless you left that out.

be cautious checking, good way to blow yourself up.

seems like you have fuel..so I'd be looking to see if there is any spark.

safe way...

leave the plugs IN

get a fresh plug

take one plug wire off the engine and connect to the test plug

crank it a few times..

see spark?

you got something worse going on ( like a stripped rv)

you do not want a situation where you have fuel blowing out of a plug hole while you are checking for spark




this fellow found out the hard way that a little gas can make an awfully big flash

welcome to GH!

[sea-one]

nmpeter, I had some suspect contaminated gas causing the needles in tha carbs swell and stick open and with the fuel pressure that builds in the tank it filled up the motor.

[nmpeter]

if that was the case, the engine would have been hydrolocked with fuel, and sorry to say when that happens on a 787, if the tech doesn't know better, they end up burning down the house so to speak.

a 787 with a hydrolock with fuel is a really dangerous critter to deal with. I actually rigged up some inserts with hose on em so I can safely get the majority of fuel out of the engine without it spraying in the hull.

op ski must have lost spark, cause in most cases with enough wide open cranking, it will eventually fire and clear itself out.

[Tesler32]

Thank guys for all the replies. I have spark something is wrong with the carbs. I swaped carbs from a 97 SPX and the think fired right up after I got all the fuel blown out of the crankcase. So with the new info what am I looking for in Stock 38mm carbs that would cause those symptoms.

[carlosdelgado]

Your issue is that the crabs have bad needle and seats and it's letting all the gas flow right into the bottom crank case. Replace them both with new ones(OEM) is best. also, Make sure that the vent for your gas tank is venting properly. Too much tank pressure is no good either. Good Luck!!!

[nmpeter]

at minimum needle/seats and diaphragm ..at best every replaceable plastic/rubber bit in the carb

[blairwill4]

There should be a check valve somewhre around the fuel neck in the front of the ski. If this gets plugged, the summer head will cause the tank to pressurize and it will force fuel out any way it... which is usually down into the carbs. I had it so bad on a polaris one year that it filled the crank case and intake manifold and dumped it out into the hull. It had me chasing a fuel leak when all it was, was a dumb plastic valve. Try replacing the vent and see what happens.