Troubleshoot Fuel Delivery Problems : low revs, bogging, surging

[Lake Anna]

Low Rev's

I have used the procedures below and have identified the problem as the fuel selector valve. This has been a great help. I have one question, is it possible to have the blockage at the fuel pickup at the bottom of the Fuel baffle screen that is only blocking the main pickup and not the reserve pick up. I have not pulled out the Selector valve to clean it but i see the diagnostic as identifying the blockage as somewhere between the main pickup in the fuel tank baffle and the fuel selector valve. I could not tell from the pictures what the filter/screen at the bottom of the baffle looks like. If that filter would screen anything going into to baffle then the problem would have to end up being in the fuel selector. Any help with the baffle filter would be appreciated. This has been a big help:thumbsup:

 

[Dakota881]

Great help thanks to all

 

[tom.lbi]

I have a 98 GTX , will the same fix apply and are the carbs the same?

 

[Pau1]

My 97 GSX had partially plugged inlet filter to the rear carb. The material I pulled out of that little filter had the texture of wool fibers. It reminded me of the old auto seat horsehair stuffing. The odd thing is that the front carb filter was very clean, so the contamination most likely did NOT flow in with the fuel. The rear carb filter was 80% full of fibers and then front carb filter was empty!

 

[tom.lbi]

I started to replace fuel lines with auto gas lines (much cheaper than Seadoo lines or Marine grade lines) I only did what I could do without doing anything to the Carbs. I cleaned the filters and the fuel reserve switch, this was full of gray line gunk. I took the ski out for a test run But ran great for about 20 min. than bogged down. End result fix the Carbs and try again. I did check the fuel pick up filter in the gas tank . No problem there it was clean.
After taking the carbs out and rebuilding them, I replaced all fuel lines . I got out on the water and low and behold same problem !!!! I found a great mechanic and told him over the phone the whole story.
He said It could be lack of oil ( this ski is oil injected ) I took it to him and after a top end rebuild it runs great. The cylinders and pistons were scored up very badly, causing it to cease up. (bogg down )
The oil pump quit working unknown to me, also their was a hole in the oil line. If the psi in the cylinder is not around 150 you may have this problem

 

[suprajake]

What a huge help, thank you! It was the fuel selector valve on mine, after bogging at WOT. While out I decided to go all the way and replace ALL the fuel lines since I had the valve out to begin with. Not sure if it was covered or not, but before you remove the valve what does work is tying a string to the screw that holds the knob on, and when you pull it through to the rear it pulls the string also, and you have an easy way to return the valve to its home when you replace it.

 

[JPX]

What a huge help, thank you! It was the fuel selector valve on mine, after bogging at WOT. While out I decided to go all the way and replace ALL the fuel lines since I had the valve out to begin with. Not sure if it was covered or not, but before you remove the valve what does work is tying a string to the screw that holds the knob on, and when you pull it through to the rear it pulls the string also, and you have an easy way to return the valve to its home when you replace it.

That's a great tip on getting the fuel selector valve back into the hole. For some hull shapes, this is easy to reach by hand. But your string technique would certainly help those with more challenging hull shapes - or shorter arms.

Glad to see this thread helped you out!

 

[blauther]

Cleaned out carbs but noticed return line not clear

I recently went through my carbs...cleaned out all the shmeg-ma...followed the carb tricks from this site (Thank you by the way).

The ski runs and idles...didn't put it in the water to test it yet, so i don't know how well it runs.

Something bothers me about the rebuild though...On the rear carb (the one without the fuel pump) the nipple that the fuel return line attaches to is pretty well plugged. When i had it apart, i had trouble blowing through it. When i looked into the aluminum body...there was just a pin hole for fuel to pass through. I tried carb cleaner and even acid, but could get much flow through it. If i filled up the nipple with carb cleaner...then put 100lbs of compressed air to the other side...it would stop the flow of air and maybe get a bubble that would come up every few seconds. In my opinion...not nearly clear enough for gas to pass through.

Is this normal? any help would be greatly appreciated.

95 Seadoo explorer
2 stroke
Dual carbs
657


P.S. I am new to this site, and forums in general. If i posted in the wrong spot can you please get me to the right spot...Thank you.

 

[jdtox]

Hello all I am new to here! I just returned from the holiday weekend and started looking for solutions to my issues with my 95 SPX and it led me here.

Unfortunately I don't have it front of me, to be able to look inside to see what color the hoses and stuff are, but I just wanted to explain my symptoms and see if you think the info in this thread could help me.

It starts up fine, but wont go much faster than idle with throttle fully depressed. However, when out on the water if I catch a wave just right or if I stand on the back and bounce the machine it seems to do something that makes it go fast like normal as long as I hold the throttle down. As soon as I let off the gas it will only go slow again. I don't know whats going on when that happens, if its sucking in air or what.

Does this sound like a fuel delivery problem?

 

[Hoosier 2001 LRV]

This post is to thank everyone on this forum for really helping me help myself get my ski running great. I also wanted to share what I did in case in helps a rookie like me.
I read many posts that all contributed to my trouble shooting and fixing. I did find something new that may help people just short of getting into the carbs.
Recently bought my first PWC, 2001 Seadoo LRV with 150 hours. It has the 947 carbureted engine. Took it for a trial run about three weeks ago to see how it ran before our family 4th of July week's vacation. It had the classic fuel problem symptoms of hitting 5,000 RPM then drop in power, back up to 5,000 RPM, drop in power, etc.
I had already cleaned the fuel filter prior to the test. One other thing I should have done was drain the fuel but I did not. After the test I:
+ Rebuilt the raves, one had a melted rubber bellows and both had their red caps screwed down tight. I cleaned everything and used replacement kits and from SBT and then put red caps flush (I read that was the standard position)
+Bought a new fuel control valve. Unfortunately it had small fittings (about 1/4 inch) and my lines were the 8 mm lines. I did not have time to get more line. I ended up cleaning my existing fuel selector valve. I did notice that during my test drive that it ran better on reserve which I understood was a symptom of this being a potential issue. So still have original valve but cleaned up and put back in service
+Gray fuel lines. Due to my procrastination I did not have time to replace the grey fuel lines prior to vacation. Mine are ugly and no doubt part of my problem. That is my next project.
+Carbs. I bought rebuild kits from SBT. When I took off the rubber covers and spark arrestor I saw that my carbs were black and shiny. i was working till late every night and decided to not get into the carbs since they looked new. I took my tools on vacation just in case it was necessary but i lucked out and did not have to rebuild (or even clean the carb fuel filters)
+Took ski on vacation for 4th of July week. We camp on a river. I filled up with 93 octane fuel. The first day I initially had the surge problem but then by end of day it was not so bad. Day two (and 13 gallons of more 93 octane fuel) it ran even better. I could get up 6,000 rpm before losing power. By end of day two I was told by a rider they thought it was now fine. Day three (and 15 gallons more 93 octane fuel) my ski was running great. We could get up to 6,500 rpm and no surge issue. Day four with more fuel it was running fuel out at 6,800 to 6,850 rpm which I understand is what to expect. Three "large" adults full out no problem. We also pulled two people on a tube no problem. Next test is pulling up a skier.

Still a lot to do on my LRV and I understand I got lucky. I just wanted to share that using good gas may help a situation. I also used the recommended full synthetic oil.

Thanks again to everyone. I also want to promote SBT. I made a few orders to them and they always shipped same day and were great on the phone actually being knowledgeable about what they sell.

Bill

 

[receveur]

did anybody respond to jdtox's post? i have exactly the same problem w/ my 97 gsx.

 

[carl1269]

Can any help diagnose this "lack of power" and rough running issue? This is a 96 sportster with a 717 engine here is a link to the audio file. This is the 3rd engine, 3rd set of carbs. we were mired with a "neutral safety" switch that was limiting the revs, but it has been bypassed. This engine starts instantly every time, and idles well, it will barely plane with one person in the boat, and feels like it wants to go, but is starving for fuel. we have changed all the lines, filters, and cleaned everything, the screws on the carbs are set @0 and 1 1/4 respectively (no the screws are not set backwards) all the fuses in the MPEM are good, there are no restrictions on the movement of the linkage (carbs are opening all the way). If I had to put a number on it, i would say the engine is @ 70% power WOT cold. after 15- 20 min, that seems to drop to about 60% power WOT. If I have posted this in the wrong place, please let me know as i am new here.
Thanks
Carl
[video=youtube;vuRoAuADpkE]http://www.youtube.com/watch?v=vuRoAuADpkE&feature=youtu.be[/video]

 

[lamajama]

Is this fuel line OK as replacement line for the gray OEM lines?

http://www.watercraftsuperstore.net...arch_Begin_Only=&sort=&range_low=&range_high=

 

[marioseadoo]

To any one who might be able to help me, or the person who made this post, i have one of the problems mentioned at the beginning, that is, when i go full throtle it will run for about 30 seconds and then power gets cut off, then i try giving it gas and it just sort of floods and dies, then i have to restart it and it will turn on fine but at this point i will not be able to get the full throtle power i got on the first run. This is my first jetski, 94 seadoo xp i believe the engine is a 650cc, the guy i bought it from had aftermarket racing carbs and filters

 

[cadyshac]

First, thanks to those who have initiated and posted on this thread.
I am new to pwc but not new to boating or doing major mechanical repairs and maintenance. I have a 96 GTI that I purchased used for a neighbor friend. It still has the original grey fuel lines. The carb's were said to be rebuilt 2 years ago but the fuel lines are still the original ones and the factory fuel filter is the only one, no inline filter nearer the carbs (yet). The problem I am having is bogging down going from part to full throttle, sometimes even stalling. When stalling occurs it takes a lot of cranking with the choke on to get started again, so not enough fuel getting to the carbs. The factory spin on filter looks ok, not very dirty. I have not had a chance to try running in reserve yet. The flame arrestor needs a good cleaning too. I guess my question is do I have to pull the carbs to check their internal screens or can I spray carb cleaner thru them while running? or add a good fuel system cleaner, like techron, after changing the fuel lines? I should have added that the idle is pretty rough, but the first couple times out it ran fine, just this last time we started experiencing the bogging going to full throttle. That makes me thing we have run enough fuel thru it to clog the carbs? or maybe I got lucky and the clog is before the carbs?

 

[carl1269]

Our issue turned out to be, we think, a plug wire-boot connection issue. I was puzzled because the thing started so well- i mean instantly! to the gentlemen who has issues going from 1/2 throttle to full. Make sure your neutral safety switch isn't acting up. if you start the motor, and then UN-plug one of the wires, you will eliminate the switch. if you run fine- change the switch- if not and you are sure your Plug wires are making good contact inside the boots, and your plugs are new, then we need to look at fuel delivery. Do not put carb cleaner in the tank, or spray it through a running engine. these are 2 stroke motors, and the cleaners will cause the oil to not adhere to the moving parts they are supposed to lubricate. after you remove the breather, you should see the carb adjustment screws. the one with the caps on it should be closed, and the other out 1.5 turns or so. if you think you have dirt in the carbs, with the engine off, pull the screws and shoot carb cleaner in there. you can take the end of the carbs off where the fuel comes into the carbs, and pull the little filter out can clean it. if you are not well versed in these carbs you shouldn't start pulling them apart-anyway like everyone says, the grey lines have to go- good luck!

 

[silver z]

To any one who might be able to help me, or the person who made this post, i have one of the problems mentioned at the beginning, that is, when i go full throtle it will run for about 30 seconds and then power gets cut off, then i try giving it gas and it just sort of floods and dies, then i have to restart it and it will turn on fine but at this point i will not be able to get the full throtle power i got on the first run. This is my first jetski, 94 seadoo xp i believe the engine is a 650cc, the guy i bought it from had aftermarket racing carbs and filters

Its sounds like you have a fuel starvation issue imo.
Sounds like while its sitting and the bowls/lines are full it runs great until you use the fuel up. Then it runs bad because it can not keep the fuel coming.... Make sense? id check the filters/lines/carbs to make sure theres no blockage anywhere. also try running it on reserve then just on to see if there a difference.

 

[bigdawgdw]

i have a 97 gsx that idles and takes fuel great on bottom but surges in and out on high.ive replaced fuel lines and been thru carbs.internal filters are spotless. from reading this im hoping its in the filters or selector valve .thanks for the info

 

[marioseadoo]

Thank you silver z, well i decided to pull one of the fuel lines that enters the carbs and i saw a green goo, inmediately made me suspicious of ethanol eating up the inside of the fuel lines and possibly all that goo has gotten inside the carbs and this is whats giving me problems, so im getting new fuel lines and had a friend who works at a boat shop clean the carbs for me. Hopefully after this is done the jetski should run fine, im a firt time jetski owner and did rode it the first time when i went to buy it and it was great. Also i should mention the last owner told me he had the engine rebuild and has performance carbs and air filters, so if i can get any suggestions or comments on this would be appreciate it.

 

[DEEz]

I want to thanks those for the info they have posted throughout the site & I will post what I have done.

I have in the past 2.5 weeks cleaned the carb filter & replaced my gray fuel lines, added a inline fuel filter & replaced my float & soldiered my fuel sending unit.
I let brake cleaner soak in my fuel selector valve & then slowly applied pressured air & blew the rubber blockage out (shot out like a bullet LoL). Replaced my battery & the killswitch cord.

 

[smirnoff]

Great thread.....have a 1996 XP & 1998 SPX (both 800's) that started bogging/missing this season. Changed plugs & siphoned the old gas, still had issues.

Found this thread & changed all the Grey fuel hoses with Goodyear fuel line (the SPX had 5/16" fuel lines). I also pulled the fuel tanks which was simple & glad I did. Remnants of deteriorated fuel hose were floating around from the fuel return lines in both, also found a screw at the bottom of one of tanks.

1996 XP: A black tar like substance was found in the fuel baffle, fuel filter, & internal carb filters (also smelled like tar). Green slime was found at the fuel selector, along with the fuel hoses between the carb's.

1998 SPX: Grey pieces of deteriorated fuel hose were found at the bottom in the fuel filter & a plugged fuel selector, green slime was found in the fuel hoses between the carb's & also inside of the carb's.

I have never pulled the carb's before.....but, it was not that difficult. Glad I did, because this could be a routine maintenance item. I also added inline fuel filters to help prevent the carb's filters getting clogged in the future. Over the winter, I am going to fix the fuel baffles (fuse on the SPX), not sure yet on the XP (only 2 bars show).

 

[marioseadoo]

To JPX: what year and model did those carbs come off? i have a 94 xp 657cc and they are not even close to what mine look like. Does anyone have a 94 xp with the carbs i need to see how do the fuel lines go

 

[smirnoff]

Great thread.....have a 1996 XP & 1998 SPX (both 800's) that started bogging/missing this season. Changed plugs & siphoned the old gas, still had issues.

Found this thread & changed all the Grey fuel hoses with Goodyear fuel line (the SPX had 5/16" fuel lines). I also pulled the fuel tanks which was simple & glad I did. Remnants of deteriorated fuel hose were floating around from the fuel return lines in both, also found a screw at the bottom of one of tanks.

1996 XP: A black tar like substance was found in the fuel baffle, fuel filter, & internal carb filters (also smelled like tar). Green slime was found at the fuel selector, along with the fuel hoses between the carb's.

1998 SPX: Grey pieces of deteriorated fuel hose were found at the bottom in the fuel filter & a plugged fuel selector, green slime was found in the fuel hoses between the carb's & also inside of the carb's.

I have never pulled the carb's before.....but, it was not that difficult. Glad I did, because this could be a routine maintenance item. I also added inline fuel filters to help prevent the carb's filters getting clogged in the future. Over the winter, I am going to fix the fuel baffles (fuse on the SPX), not sure yet on the XP (only 2 bars show).

Also - before I replaced the hoses & pulled the carbs, I went & talked to a couple of reputable SD authorized service shops to have them quote a price. Both quoted T&M, not a fixed price, which came to $1000-$1200 in labor not including parts for each machine.....:leaving:

 

[36cfjoe]

Quick question...I have a seadoo SP...the basic lowest model. It has only one carb....so on the carb, which fuel line is return and which one is fuel to the carb. The lines are stacked top and bottom and not labeled on the carb.

 

[DEEz]

Quick question...I have a seadoo SP...the basic lowest model. It has only one carb....so on the carb, which fuel line is return and which one is fuel to the carb. The lines are stacked top and bottom and not labeled on the carb.

On my 1998 GS.
On the carb end.
Top line goes to tank ("return"),
Bottom line comes from the fuel screen filter under the hood ("fuel feed line").