Seadoo gtx rfi 1999 problems

[Rickdug]

Hi i
Am new to the forum but looking for some advice on my seadoo it is a 1999 gtx rfi 787cc ,
the problem is it will run badly on 1 cylinder but some times will
Run fine, i have replaced the spark plugs about 3 times in the last week as it keeps causing 1 plug to
Be broke beyond the basic clean etc, i noticed the cylinder that is running ok
Seem to have allot of oil on the plug after running it, i dont know if that is normal ? I have cleaned the air filter checked all the connections and replaced all the fuses, what is confusing me is the way it can be running mint one minute for 3 hours then the next day the top cylinder wont even fire? I believe the exhaust valves are called rave valves ? Well i checked if they are free and they are, i drained the fuel tank and refilled it as someone suggested water in the fuel that didnt fix it, it has had a recent rebuild new pistons and rings, and with new spark plugs both leads are giving a great spark. One other thing i noticed was when running (but badly) the top cylinder once switched off and plugs removed would push allot of exhaust fume out the spark plug hole where as the bottom cylinder which fires great would not at all. I hope that perhaps someone could help me and if you need any more information just ask.
Thanks in advance
Richard

 

[Dr Honda]

Sorry for the problems................... But lets figure it out.


OK... so you say one plug is fouling, and the other isn't.

It could be a few things.

1) I know you said it has good spark.... but have you tried cutting the wire back a little? The spark plug wires can corrode at the boot connection. Sometimes cutting the wire back (abotu 1/4") will get you into clean wire, and a stronger fire.

2) When you did the top-end... did you have the injectors checked? If the injector is leaking... then you will be getting more fuel in that jug all the time. One thing you could do is switch the injectors, and see if the problem follows. If it does, then replace them... or have them serviced.

3) Do you have excessive smoke? Extra oil will foul the plug(s) and make smoke. Especially at idle.

4) Have you checked the compression? If there is a problem, and if for some reason the one cylinder has low compression... it could foul the plug.


With all that said... I'm assuming after you put the new spark plugs in... the engine will run good. (at least for a while)

 

[griz400]

=====================

 

[Rickdug]

Hi yes when replacing the plug it will run well for a while, i will try cutting back the leads hopefully there is enough play other wise ill get new ones, the injectors were not done perhaps this is also the problem is there an easy way of getting to them without lifting the engine ? There is excessive smoke once replacing the plugs but that goes after a minute of running with clean plugs, i will check compression really dont fancy another rebuild price :s
Thanks again

 

[1MACGYVER]

Im not sure if its the same but on my 05 3D 787RFI seadoo made it so at idle (under 3000rpm) it only injects and fires on the front cylinder as a fuel saving exercise. The problem is it still draws oil and air through which fouls the rear plug.
The easy solution is dont idle it much, keep blipping the throttle or shutdown when you are still in the water

 

[Rickdug]

Hi guys thanks for the help, compression is 125 on the bad cylinder and 135 psi on the good so very happy with that, going to check the injectors in a bit does any ome think it could be the coil ? As it is giving a strong spark ?

 

[1MACGYVER]

i just saw your earlier post, the injector rail is held on with 2 bolts right next to the injectors, m10 i think, undo them and wiggle the whole rail out. then its easy to unclip the hose from the end of the rail.
This is the part if that helps visualise the position.
http://www.ebay.com/itm/Sea-Doo-1999-GTX-RFI-Fuel-Rail-W-Injectors-Seadoo-/230608123840?pt=Personal_Watercraft_Parts&vxp=mtr&hash=item35b150b7c0#ht_500wt_1055

 

[Rickdug]

Thanks allot for that

 

[Rickdug]

So i switched the injectors and it seemed to be those so have cleaned them and put it back together, it seems to run allot better but still on the top cylinder takes a second and with throttle down until it starts firing at full rev then it seems to run ok until you drop the revs and put the throttle back down it takes a second to fire up properly and then it seems fine, until you really rev it and then it will push back pressure through the air box any ideas ?