Mixing spark plugs

[robin savell lloyd]

I am no expert but your plugs do not look that bad to me. They do not look like the correct ones but even at that they look like they would fire in a michine that has a good spark. If you have 2 identical machine then you may be in luck. I am thinking that you may have a weak spark. I would start and make sure that you have a very good battery. Then I would take the coil off of the good ski and put it on the one that has the problem and see if that fixes your problem. :cheers:

 

[tomcat&family]

The battery is good... I checked that yesterday, and my charger said that it had a full charge. It had 12.9 volts out of the boat with no load according to the charger. That said, it typically reads about 0.2 volts low according to my volt/ohm meter, so it was probably somewhere around 13.0-13.1 volts.

Anyway, the ignition coil, eh? Do you think that the corroded plug wire end could have caused a weak spark?

Those are the correct plugs, by the way. They're just the HGK Iridium plugs vs. the standard HGK plugs.

 

[robin savell lloyd]

A corroded wire could have been the problem but I am not sure. After looking at your parts breakdown they only show a replacement wire with boot atached so I am not even sure if that boot was to be removeable. Being that you have acsess to other parts this should be easier for you to find out the problem then any one else. There does not seem to be many electrics pros out there offering alot of help with this type of problem as I have done a few searches and see a few questions close to yours without any replies or not very good replies :cheers:

 

[timmyboy76]

:agree: wit Robin, on the spark plug pics,..I'd take those looks anyday, over the way my plugs look...you say the wires already short, go to auto parts, and buy 2 new plug wires(7mm), and install those with the boots that come with them...dont have to be a fancy name brand, either...:cheers:

 

[tomcat&family]

A corroded wire could have been the problem but I am not sure. After looking at your parts breakdown they only show a replacement wire with boot atached so I am not even sure if that boot was to be removeable. Being that you have acsess to other parts this should be easier for you to find out the problem then any one else. There does not seem to be many electrics pros out there offering alot of help with this type of problem as I have done a few searches and see a few questions close to yours without any replies or not very good replies :cheers:

Well the boot appeared to thread on and off, so I'm pretty sure that they are removable. They were BOSH brand, if I recall correctly.

:agree: wit Robin, on the spark plug pics,..I'd take those looks anyday, over the way my plugs look...you say the wires already short, go to auto parts, and buy 2 new plug wires(7mm), and install those with the boots that come with them...dont have to be a fancy name brand, either...:cheers:

One plug is still different from the other, though- that's what bothers me. It also acted like the plug was fouled. I think I'll try and see whether or not anything I have done thus far has fixed it rather than spending more money on something that I might not need.

If it was a coil problem or if it was a wire issue, then why isn't it having this problem all of the time? It runs pretty well for an hour or two.

 

[robin savell lloyd]

My thought is if you are haveing a weak spark the plug will not be able to burn the fuel completly and if the plug gets just a litle dirty the weak spark may not be able to jump across as it should. The weak spark may require a new plug for it to fire once it becomes just a litle dirty it is no longer sparking. You should not have to spend a dime guessing a spark problem if you are doing the work your self and you have a nother ski that you can temporarly use a part from to make sure that is the problem. :cheers:

 

[tomcat&family]

I guess I'm just having a hard time understanding why a plug that is not burning enough fuel is completely dry when the others are slightly wet. But I do see you point about the weak spark, I suppose.

Lets say it is a weak spark... being that one is working properly, what could be wrong. One works well, so the battery, battery connections, etc. are all good. What hooks up to one spark plug that is not connected to the other one?

 

[robin savell lloyd]

About the cylinder that has a wet spark plug. I know this seems hard to believe but I just read that RFI engines runs on one cylinder at idle. This came from the most experianced pwc mechanic I know of. He said that it is normal for 1 plug to be wet. This just dont seem right to me but I have an idea of what he means. :cheers:

 

[robin savell lloyd]

I guess I'm just having a hard time understanding why a plug that is not burning enough fuel is completely dry when the others are slightly wet. But I do see you point about the weak spark, I suppose.

Lets say it is a weak spark... being that one is working properly, what could be wrong. One works well, so the battery, battery connections, etc. are all good. What hooks up to one spark plug that is not connected to the other one?

Like I have said I am no expert on seadoo I have worked on a few thousands other types of engines so I am only giving hypothesis. The info I am giving you are guesses. You are way ahead of the game as you have another ski that you can use parts from to find out the problem. I have read that even pross take this aproach from time to time when they are not 100 percent. :cheers:

 

[tomcat&family]

About the cylinder that has a wet spark plug. I know this seems hard to believe but I just read that a RI engines runs on one cylinder at idle. This came from the most experianced pwc mechanic I know of. He said that it is normal for 1 plug to be wet. This just dont seem right to me but I have an idea of what he means. :cheers:

The more recent RFI engines run on one cylinder at idle, but not these. Besides, both of the plugs in the other GTX RFI are exactly like the one slightly wet one on the troubled boat. That is why I believe there is something up with the front cylinder. It is the only one of four plugs that are different.

Like I have said I am no expert on seadoo I have worked a few thousands other types of engines so I am only giving hypothesis. The info I am giving you are guesses. You are way ahead of the game as you have another ski that you can use parts from to find out the problem. I have read that even pross take this aproach from time to time when they are not 100 percent. :cheers:

I'm just worried about messing things up, I guess. I really hate to take apart a working ski, but it is looking like I have no other choice.

I didn't get to go out for a ride today... it was rather chilly this morning and it's still pretty choppy out there right now. I also decided to get some work done with the tractor. Maybe tomorrow.

Thanks.

 

[tomcat&family]

Time for some updates:

I went out for a run today, and she seems to be doing better. The water was pretty rough when I went out the first time (1-3 footers, I would say), but it was a fun ride. We were out for probably an hour and a half in all. I made several speed passes in those rough conditions, and managed a top speed of 57mph. Not bad for the conditions! ... 1mph slower than my previous top speed recorded on flat water! The RPMs were also higher... the rev limiter was actually kicking in when I'd air it out, and she was running a steady 100-200rpm higher. I didn't let the boat idle much, though. If we slowed down, I staid on the throttle a touch to keep the RPMs up. When I got the boat back on the lift, I pulled the plugs. They weren't new... have 3-4 hours on them now, and the last set only lasted for an hour or so. The front plug (the one in question here) was slightly wet as opposed to dry like it was. The back plug was still slightly more wet, but that could be because I am not using new plugs. Both of the plugs were brown in color as opposed to black (like a chocolate color).

The water calmed down a bit just before dinner time, so I went out for a quick speed run. The water was still choppy, but the waves were no larger than a foot in height. I manged to obtain a top speed of 61mph at with RPMs in the upper 6700's to low 6800's. With the second GTX RFI, I manged to get 62mph with RPM's just slightly higher (upper 6800's to low 6900's).

I would guess that the one mph difference is probably due to a difference in the speedos, or maybe in the RPMs? It appears that I have fixed the probem, no? The boats are now almost dead-on equal in speed, when there was a 5mph difference before.

Thoughts? Should I be concerned with the slight difference in RPMs? Could the high performance plugs in boat number 2 account for that difference?

 

[tomcat&family]

Sorry to bump post, but does anyone have any answers to the questions I posted above?