Personal Water Craft Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
6 Posts
Discussion Starter #1
hello i have a 2004 yamaha fx 140 and it has been running okay the past few summers but this year it stared doing funny things. two weeks ago we ran it kinda low on fuel on the way to put more in it. and it would not rev up at all. well we finally got fuel in it and it ran ok after that but i did noticed that it would only rev to about 8300 rpm. and it sucked a full tank of gas in about an hour and a half. so get home and put new plugs in it and there gapped at .32 like it calls for went out last night and it was sluggish from a stop and would only hit about 43 45 mph at about 8600 rpm. and it went through a full tank of gas in a bout an hour of ride time. Is there a fuel filter in it some where were i might have plug it a little or any ideas, the air filter is in good shape. and nothing looks like it is getting pinched any where, the prop is in good shape with no dings of any sort the shaft is straight and nothing around it.
I'm stumped and dont reallly have the money for the shop just bought a house. so any ideas i haven't thought of would help before i do have to take it to the shop lol.

Thanks alot guys and gals.
Jimmy
 

·
Registered
Joined
·
3,033 Posts
I'll throw out some guesses:

Still sounds like a bad plug not firing............I know you've changed the plugs, but this is THE most common problem for this model ski, so you might want to do the plugs one more time just in case. When you pull the plugs look for a wet one (unburnt fuel).

Could you have bad gas? Have you tried higher octane? Have you tried a fuel injector cleaner (Yamaha makes a good product called Ring Free Plus, Seafoam is another good product)?

There are small fuel filters inside each injector. You have to remove the throttle bodies and the fuel rail to get to them and clean them. It is also possible for debris to clog the fuel pump or the check valve (see below for checking fuel pressure).

Don't discount the air filter as a problem just because it looks OK. Even a little contamination of the air filter can lower performance. Take it off an run the ski without it to see if there is an improvement.

Have you checked to see if you have spark on all cylinders? Sounds like one cylinder not firing (bad coil?).

Have you got good fuel pressure from the pump? Difficult to tell without a special gauge (should be 46-47 psi). You can remove the hose and hold it horizontal and crank it to see if you get a good stream of fuel out of the hose as an estimate.

I still can't explain the increase fuel consumption, unless there is a problem with the throttle assembly or a fuel injector, or you are just pumping unburnt fuel through one cylinder.
 

·
Registered
Joined
·
6 Posts
Discussion Starter #3
thanks ernest ill go home and give those a shot. hopefully one of them work. ill let you guys know if i find the issue.
Jimmy
 

·
Registered
Joined
·
6 Posts
Discussion Starter #4
k i changed the plugs and there gapped at .32 checked the fuel pressure it was good. checked the pistons compression and all are with in 4 psi of each other. pulled out the air filter and took it for a spin and it would rev up to about 91 9200 rpm. better than 8500ish. but not where i think it should be. and it would only hit about 49 51 mph and was still slow and slughish taking off.....
also i had made the stream of water that it shoots up in the air come straight out the back (do to towing my kids) but just for thought i put the stock one back on it and it would only shoot the stream about 3 or 4 feet in the air compared to the 20 ish feet it use to????? is there a faulty water pump that could be dragging down the motor or where does the water pump pick its water up from if it is from the ride plate/prop and could it be (cavatating) and if so how or what do i look for when inspecting that?
Thanks guys and gals
 

·
Registered
Joined
·
3,033 Posts
Have you taken off the intake grate and checked the pump for something that may be lodged in there?
 

·
Registered
Joined
·
6 Posts
Discussion Starter #6
tore the whole jet drive apart and on the impeller i found about an inch and a half long and half an inch wide place on all three blades that are pitted and worn down a little about half way up the very out side of the blades. there is one small small flat spot on the edge of one of the blades sharp edges like it hit a small rock. i think but aint sure that this is my problem if those pits are causing air bubbles that would cause the stream that it shoots up to be filled with bubbles and not water pressure also causing it to not have the full water jet out of the back. does that sound logical? buy the way i caint spell. lol also the part it spins in looks kind like some one used some fine sand paper and sanded it smoot. i think it is from the blade can i take a drimal and file the pits on the prop smooth with out hurting the performance in terms making the prop work for the rest of the summer till i can get a new one this winter? and is it normal for the peice the prop spins in to look like that or am i going to need a new one of those too. and should i take some fine sand paper and sand it a little?
thanks a lot ernest. you,ve been a big help.
jimmy
 

·
Registered
Joined
·
3,033 Posts
You are right, even small dents and dings in the impeller can cause cavitation and reduce performance. Just as important is that the impeller needs to fit very tightly inside the housing (.35-.45 mm). You should check this clearance with a feeler gauge at each blade. Be careful smoothing the blades and the inside of the housing if it will cause the gap between the impeller and housing to increase, since you will end up loosing even more performance.

You may very well need both a new impeller and a new housing, or I'm pretty sure that you can get a plastic wear ring to go in the housing for your model that would be a much cheaper solution, and will give you a very tight fit between the impeller and ring. The plastic wear rings also offer some measure of protection against debris, in that the cheap plastic gets destroyed instead of more expensive metal parts.
 

·
Registered
Joined
·
6 Posts
Discussion Starter #8
drimmeled the prop cleaned the edges and wet sanded it smooth. put back together and hit the lake hopeing.. lol well my stream was back to normal shooting way up and it was super fast out of the hole shot and top speed was up around 59 61 mph. so i think it will work for the rest of the summer. thanks alot ernest T your the man. talk to you all later .
jimmy
 

·
Registered
Joined
·
3 Posts
hi guys, would any one know why!!!!! after taking my yam fx140 out for a play (with only 69hour on it) when i got it back home after about a 13mile journey it wouldnt start when i was trying to flush it out,,, i washed it all off and was ready to flush and all it one is just turn over, it was a rite sod to fire, however after aprox 5 mins it started and is now fine again ,, can anyone help ???? many thanks guys
 

·
Registered
Joined
·
142 Posts
When you flushed it out did you start the engine first then turn on water?

BTW, I have never working on my own ski's or cars for that matter, I took my 2002 FX140 to a shop the beginning of this season and had them replace plugs and change oil, look over system, and it was very expensive, think maybe 150$ dollars just for the plugs, but can not remember exactly right now.
The thing is reading stuff like this makes me want to try to change my own plugs and oil, but I have a real issue with fucking up mechanical stuff, I am better with computers than engines :(

If you lived close to Charlotte NC Earnest let me know, I would love to have someone look over my ski sometime that I could really
trust.
 

·
Registered
Joined
·
3 Posts
Lol I have only just bought the ski but I have had one before,, to change oil and filt/plugs is easy.. Use a filter strap and a long lever bar or a pair of large grips to remove the oil filt, (and beshore to use plenty of rags under the filter to save a big mess when it breaks its seal) the oil will need to be drawn out of the oil tank as it's a dry sump, in my work shop I have an ideal tool,, it's a buildge pump off a small boat,,
 
1 - 11 of 11 Posts
Top