Troubleshoot Fuel Delivery Problems : low revs, bogging, surging

[JPX]

Do you have any of these symptoms on your carbureted 2-stroke engine?
- Low revs in water with throttle all the way on
- Okay revs out of water, but low revs in water
- Bogging when going from idle to full throttle
- Surging of revs
- Intermittent or sudden cutting out of engine when at speed

Then you might have a fuel delivery problem. Hopefully your use of the search feature in seadooforum.com has led you here!

First: confirm you already put new, clean, and properly gapped plugs and confirmed there is spark to BOTH cylinders. As this only costs $2/plug and a couple of minutes, you should do this before moving on.:toetap05:

For those of you with Seadoos made in the 1990s, you should expect to have some type of carb problems if you have the original gray fuel hoses. The hose breaks down internally and the residue accumulates in the filters.

I will break this up into two approaches since not everyone is up for a full fuel system rehabilitation and not everyone is satisfied with piece-meal fixes. Choose what is right for you.


Easy, but limited chance of success guide:

1. Clean out spin on fuel filter. Make sure the o-ring is there. Don't use carb cleaner or you will dissolve the filter's fiber mesh.​

​

2. Try running your boat on RES - this would point to a clogged fuel selector valve.​

​

3. Remove the fuel selector valve and clean it out with carb cleaner. Blow it out with compressed air in the ON and RES positions.​

​

4. Change to new spark plugs. You should have already done that.​

5. Pull spark plug wire from boot. Trim 1/4" off the tip of the wire. Reinstall to the boot and ziptie it back on.​

6. Make sure your carbs' high speed adjuster is set to fully closed clockwise (zero). Set low speed adjusters to fully closed clockwise, then turn counterclockwise specific turns to your engine. Use the idle screw to set idle speed only - do not use low speed adjusters to set idle speed.​

​

7. Check all fuel hose connections are tight and that the check valves freely blow one way, but do not the other (one above the fuel tank and one on the side of the hull from the fuel tank):​

​

More complicated, but high chance of success guide:

1. Remove all grey fuel hose (if you still have it) and replace with black automotive fuel hose. The grey stuff breaks down on the inside and clogs the carbs' internal filters. You'll need mostly 1/4" black automotive fuel hose (Coast Guard approved marine grade fuel injected hose is top of the line, but costly). Get 25 feet of it and about 30 stainless steel #04 hose clamps....no zip ties!​

​

2. Remove the carbs and disassemble for cleaning the internal filters.​

​

3. Better yet, plan for rebuilding the carbs​

Here are some excellent resources for cleaning/rebuilding the carbs and setting them up properly:

Excellent carb rebuild guide thread by qstorm.​

seadoosnipe's carb theory guide thread​

Parts finder thanks to SeaDooWarehouse.com​

JPX's 1996 HX carb rebuild thread with lots of photos (my own personal experience)​

- Make sure your carbs' high speed adjuster is set to fully closed clockwise (zero). Set low speed adjusters to fully closed clockwise, then turn counterclockwise specific turns to your engine. Use the idle screw to set idle speed only - do not use low speed adjusters to set idle speed.​

​

4. Clean spin on external filter, clean out fuel selector valve.​

​

5. Pull fuel baffle from the tank and check for any obstructions on the intake screen. If you have lots of junk in the fuel tank, siphon out the gas and suck out the contaminants, then refill with fresh gas. If your fuel gauge doesn't work or always shows empty, check out this link while you have everything in pieces Fix for Fuel gauge empty or light on when tank is full (fuel baffle/sender)​

7. Check all fuel hose connections are tight and that the check valves freely blow one way, but do not the other (one above the fuel tank and one on the side of the hull from the fuel tank):​

Note: This is primarily directed towards carbuerated 2-stroke models, but the principles apply to all gas engines. Those of you more experienced in the RFIs and 4-TECs feel free to chime in so we can include those specific guides on this thread as well.

 

[RNispiros]

JPX, First great informational posts! Being new to PWCs, your posts are helpful and insightful. (As well as Karl's and other folks)

So for replacing the Grey fuel hoses in my 1994 GTSs, are marine grade fuel hoses all created equal or is there a material advantage to one type or another? i.e. fuel hose with an inner liner as opposed to a non-lined reinforced hose. I'll replace the tie wraps with SS hardware.

I plan on rebuilding the carbs as well as I am experiencing the difficult cold start other have posted on various threads. Run great once warmed up, but difficult to get started on a cooler morning. (Compression is good, runs and idles well once warm)

Anyway, thanks again for getting info out there and hope the answer to this post benefits others getting ready to do a similar job. :cheers:

Rich

 

[JPX]

Reinforced fuel injection hose would be the best, but best comes at a sgnificant cost. I would expect that even non-fuel-injected hose will last for MANY years of service even though it is neither reinforced nor lined.

Maybe in 10 years we'll all be on here complaining about how black automotive fuel hose is contaminating the carbs!:rofl:

 

[RNispiros]

Thanks! I'm on it. I'm replacing the hoses in the first GTS this evening. I'm rebuilding the carbs once I can locate a supplier for the kits. (Didn't find one in the parts listing above... )

Rich

 

[illibuz]

backfiring?

my seadoo is bogging and dying when i give in full throttle, it is also backfiring. Do you think going through the carburetor will fix the backfiring or could it be bad gas?

 

[kustomkarl]

Replace the fuel and clean the carbs...it's a double wammy...

Karl

 

[Nate Surveyor]

How to remove the baffle pick up from the fuel tank?

Gads! Seems that ya hafta remove the fuel tank!

I have the steering yoke off, (thought I could pull it up thru the hole) and no cigar!

OK, I got it out. I pressed down hard on the top of the tank, Pushed foreward hard, and lifted it out through the hole from the removed steering yoke, then pushed the bottom toward the back of the Doo, and got it out. Some crud on the bottom of the fuel baffle. The fuel gauge does not work, and it appears the sending unit is shot. Gads. USED one is 30-60 bucks!



Nate

 

[Seadooski041]

difficult start

I have a 94 GTS, after i prime it a couple times, it fires right away then dies. After that when i try to start it, the engine just turn. Once I prime it again and give it full throttle the engine turns for a good 5 seconds before you can hear it finally firing. You have to hold down the starter button for another second or so after you hear that and then it fires right up and takes off normally. What could cause this? It has had cleaner through the gas, new plugs gapped at .5, new filters, and the carb has been taken apart and cleaned. Also, more recently, it has started either stalling or cutting out when going over wake or choppy water. A quick punch of the start button fires it right back up again. It is highly annoying playing in the waves and it cutting out all the time. What might cause that? (we had a full tank of gas in it).

You information above is great and I plan on follow ing your instruction, but could you give me more guidance on the carb screws and how exactly to adjust those? I am ok with motors, and can hear irregularities but have no experience adjusting screws besides my lawn mower.

Thanks alot!!

 

[livinlarge]

Wow,
Just joined and already have a interesting piece of trouble shooting info. The idea about the fuel selector valve is great. Thanks.

 

[Nate Surveyor]

Looks like a bit O' spam.

Maybe zap it with some carb spray?



N

 

[mricharde]

Replaced fuel Lines

Great posting- has kept me busy for several weekends.
I have a '96 GTS, replaced the old grey fuel lines and discovered the neck on the fuel tank was cracked. Checked into a new one and was told it would be replaced for free as part of a recall. That was good news!
My question- now that everything is replaced, I cant seem to get fuel flowing into the carb. Is there a recommended method to prime the system and get fuel flowing again?

Thanks!

 

[hfgreg]

Bumping this thread.

 

[mmhyson]

ok this may sound stupid but is the fuel selector valve the fuel valve that allows you to turn the knob to reserve. gas on . and gas off? and where is a good place to get this valve

 

[voodoo]

This site, and many others have the whole thing 25bux - it can be fixed but if used in brackish water then maybe best to put in a new one.

 

[mmhyson]

i didnt see if for 25 bucks can someone possible post a picture of the selector valve

 

[ssilcox]

Does anyone have the pictures that were in the thread originally? Going to work over my 96 GTX, and the pics would come in pretty handy.

Thanks!

 

[JPX]

Does anyone have the pictures that were in the thread originally?

I've re-hosted the photos. So here is an updated posting on this topic with the photos:

Do you have any of these symptoms on your carbureted 2-stroke engine?

- Low revs in water with throttle all the way on
- Okay revs out of water, but low revs in water
- Bogging when going from idle to full throttle
- Surging of revs
- Intermittent or sudden cutting out of engine when at speed​

Then you might have a fuel delivery problem. Hopefully your use of the search feature in seadooforum.com has led you here!

First: confirm you already put new, clean, and properly gapped plugs and confirmed there is spark to BOTH cylinders. As this only costs $2/plug and a couple of minutes, you should do this before moving on.:toetap05:

For those of you with Seadoos made in the 1990s, you should expect to have some type of carb problems if you have the original gray fuel hoses. The hose breaks down internally and the residue accumulates in the filters.

I will break this up into two approaches since not everyone is up for a full fuel system rehabilitation and not everyone is satisfied with piece-meal fixes. Choose what is right for you.


Easy, but limited chance of success guide:

1. Clean out spin on fuel filter. Make sure the o-ring is there. Don't use carb cleaner or you will dissolve the filter's fiber mesh.

​

2. Try running your boat on RES - this would point to a clogged fuel selector valve.

3. Remove the fuel selector valve and clean it out with carb cleaner. Blow it out with compressed air in the ON and RES positions.

​

4. Change to new spark plugs. You should have already done that.

5. Pull spark plug wire from boot. Trim 1/4" off the tip of the wire. Reinstall to the boot and ziptie it back on.

6. Make sure your carbs' high speed adjuster is set to fully closed clockwise (zero). Set low speed adjusters to fully closed clockwise, then turn counterclockwise specific turns to your engine. Use the idle screw to set idle speed only - do not use low speed adjusters to set idle speed. (717cc HX carbs shown below)

​

7. Check all fuel hose connections are tight and that the check valves freely blow one way, but do not the other (one above the fuel tank and one on the side of the hull from the fuel tank):

​

More complicated, but high chance of success guide:

1. Remove all grey fuel hose (if you still have it) and replace with black automotive fuel hose. The grey stuff breaks down on the inside and clogs the carbs' internal filters. You'll need mostly 1/4" black automotive fuel hose (Coast Guard approved marine grade fuel injected hose is top of the line, but costly). Get 25 feet of it and about 30 stainless steel #04 hose clamps....no zip ties!

​

2. Remove the carbs and disassemble for cleaning the internal filters.

​

3. Better yet, plan for rebuilding the carbs

Here are some excellent resources for cleaning/rebuilding the carbs and setting them up properly:

Excellent carb rebuild guide thread by qstorm.

seadoosnipe's carb theory guide thread

Parts finder thanks to SeaDooWarehouse.com

JPX's 1996 HX carb rebuild thread with lots of photos (my own personal experience)

- Make sure your carbs' high speed adjuster is set to fully closed clockwise (zero). Set low speed adjusters to fully closed clockwise, then turn counterclockwise specific turns to your engine. Use the idle screw to set idle speed only - do not use low speed adjusters to set idle speed.

​

4. Clean spin on external filter, clean out fuel selector valve.

​

5. Pull fuel baffle from the tank and check for any obstructions on the intake screen. If you have lots of junk in the fuel tank, siphon out the gas and suck out the contaminants, then refill with fresh gas. If your fuel gauge doesn't work or always shows empty, check out this link while you have everything in pieces Fix for Fuel gauge empty or light on when tank is full (fuel baffle/sender)

 

[ssilcox]

Incredibly helpful. Thanks so much!

 

[jjarrett]

Just what the doctor ordered!

This is a great post! Now my 97 XP runs so much better. It's amazing how much blue-green crud came out of the internal filters. I was having problems with the carbs starving for fuel at high speed. The PTO carb seemed to have more of the line crud in the filter. I would like to add that you need several feet of 8mm or 5/16" tubing for the fuel lines from the pick-up tube to the fuel selector and then to the filter. I couldn't get the 1/4" tubing to fit the larger nipples.

 

[mrwolf]

Great Thread, i think this is what i need for my HX. I am experiancing issues with the ski starting, either from cold or warm. Once the ski starts it runs well until you stop and then it will stall or not restart. Could this be a fuel problem?

The ski has the old grey lines which going by this post need to be removed as a first then rebuild the carbs.

The ski also has compression of 120 in both cyclinders, which i think is on the low side, could this cause the starting issue?

Cheers
Matt

 

[cbr1000dude]

I have a 97 GTI that has been trouble free and a joy to own. It's always run fine. Well, yesterday I took it for it's first run of the year, and it ran great up to 40 mph, then bogged down and died. It restarted right away, but wouldn't take much throttle. So today I reread this thread, and got up the courage to change the gray fuel lines. Not too bad once I got the air box off, why they need 12 bolts and 6 clips is beyond me. The lines were loose, and had green goo on the ends. They had to be sucking air. Runs fine out of the water......well see.
I'll try it this weekend. If it still bogs, I'll get a carb rebuild kit.
Thanks for the info.
Edit...I checked with the Ski Clinic in Antioch, and they had a base gasket and carb kit for $60, so I took it off and replaced the internal filter and rubber parts. There were some fine particles, but no goo. It looked great for a 14 year old carb. Now I feel better about launching it this weekend. A 5 mm hex socket on a shortie ratchet sure speeds up the r and r. Also, the carb hold down bolts (6 mm hex) had some sticky sealant on them and in the holes. It came off with lacquer thinner which made reinstalling a lot easier. Not some bolts you want to cross thread for sure! I used blue loctite on all the threads.
Edit 4/30/11 We took it out to sugar Barge and launched it today.......runs great! The only problem was the wind was blowing about 35 mph! Hopefully tomorrow it will be nicer. It's suppose to be near 90 degrees later in the week! Yeah!

 

[Brunaveli]

I am trying to take out the carbs in my 97 XP. Seems pretty self explanitory but I am still having difficulties. Any help?

 

[Brunaveli]

My XP runs great and is in mint condition, but the last time I was out it was kind of bogging out a little, and when me and my friends were out whenever we were take turns riding it we would turn it off to exchange, then back on like a minute later but sometimes it wouldnt start right back up and the start button would have to be held for a little bit and give it some gas. I have read that the lines or filters might be clogged with some gunk. I am just unsure of how to take the carbs off as I am very new to this

 

[Brunaveli]

Can I just unscrew the 4 screws on the fuel pump to access the filter without the other steps, just to check the filter?

 

[oldbuck]

Can I just unscrew the 4 screws on the fuel pump to access the filter without the other steps, just to check the filter?

Just cleaned my filters today on a GSX which I think is similar to your XP - you can't get to the back carb/filter without removing the front carb. Easy job though.