• Welcome to Jetboaters.net!

    We are delighted you have found your way to the best Jet Boaters Forum on the internet! Please consider Signing Up so that you can enjoy all the features and offers on the forum. We have members with boats from all the major manufacturers including Yamaha, Seadoo, Scarab and Chaparral. We don't email you SPAM, and the site is totally non-commercial. So what's to lose? IT IS FREE!

    Membership allows you to ask questions (no matter how mundane), meet up with other jet boaters, see full images (not just thumbnails), browse the member map and qualifies you for members only discounts offered by vendors who run specials for our members only! (It also gets rid of this banner!)

    free hit counter

2008 WaveRunner troubles

boudin

Jet Boat Addict
Messages
312
Reaction score
245
Points
122
Location
Lake Livingston, Texas
Boat Make
Yamaha
Year
2008
Boat Model
AR
Boat Length
21
Sorry, I'm not following how the fuel tank check valve could affect anything here. The difference in 'woosh' sounds you are hearing could just be the difference in the amount of fuel in each tank. Besides, when the check valves go bad, it's usually in the other direction.

The fuel pressure regulator will keep the pressure at ~46psi. A clogged fuel pickup intake screen could be affecting pressure or flow. It's attached at the bottom of the fuel pump and requires removal of the sender assembly to check.

-Greg
 

Midnight2V

Jet Boat Junkie
Messages
140
Reaction score
88
Points
127
Location
Houston Area
Boat Make
Yamaha
Year
2022
Boat Model
AR
Boat Length
25
Sorry, I'm not following how the fuel tank check valve could affect anything here. The difference in 'woosh' sounds you are hearing could just be the difference in the amount of fuel in each tank. Besides, when the check valves go bad, it's usually in the other direction.

The fuel pressure regulator will keep the pressure at ~46psi. A clogged fuel pickup intake screen could be affecting pressure or flow. It's attached at the bottom of the fuel pump and requires removal of the sender assembly to check.

-Greg
Not sure what you mean by "each tank". Is there more than one tank on this model? No sarcasm intended, I genuinely don't know.

If the fuel tank were to have a clogged vent (not necessarily the check valve, but possibly the line itself), it could develop a vacuum when the fuel pump displaces fuel from the tank that is then consumed by the engine. If the vent cannot pass air into the tank to fill the void left by the consumed fuel, it could result in too much vacuum on the suction side of the fuel pump, causing insufficient fuel flow. On the flip side, if the tank was building pressure, you are probably right in that the FPR should maintain pressure at the proper level, assuming it is working correctly.
 

boudin

Jet Boat Addict
Messages
312
Reaction score
245
Points
122
Location
Lake Livingston, Texas
Boat Make
Yamaha
Year
2008
Boat Model
AR
Boat Length
21
He was comparing the 'woosh' sound between his two skis when removing the gas cap. The pressure building up in the tank.

Need to pull the check valve out and and make sure you can blow through the top side (just with your mouth). With it removed, then also blow through the line with an air hose to see if it's clogged.

-Greg
 
Last edited:

Midnight2V

Jet Boat Junkie
Messages
140
Reaction score
88
Points
127
Location
Houston Area
Boat Make
Yamaha
Year
2022
Boat Model
AR
Boat Length
25
Gotcha, thanks.
 

Pinhacker71

Jetboaters Lieutenant
Messages
383
Reaction score
251
Points
167
Location
Verona, KY
Boat Make
Yamaha
Year
2015
Boat Model
242 Limited E-Series
Boat Length
24
Looks like a pita to get to check valve. Guess I can take off hood to gain access.
 

boudin

Jet Boat Addict
Messages
312
Reaction score
245
Points
122
Location
Lake Livingston, Texas
Boat Make
Yamaha
Year
2008
Boat Model
AR
Boat Length
21
As @Midnight2V said, try just running with the fuel cap loose if that's easier for you. Just be careful on the VX as they tend to swamp in the front. You don't want water splashing in your filler hole.

Really, though, it sounds like you have a fuel issue. I would try swapping fuel sending units with your other ski. The hard part is wriggling out the sending unit with tank still in the ski.

I've seen VXs run great with 3-year-old+ fuel. No joke. But, have you tried fresh fuel?

-Greg
 

Pinhacker71

Jetboaters Lieutenant
Messages
383
Reaction score
251
Points
167
Location
Verona, KY
Boat Make
Yamaha
Year
2015
Boat Model
242 Limited E-Series
Boat Length
24
Skis ran great when I picked up. Ran great for about an hour one day then for about 30 min on another day. All of a sudden at full throttle just lost power. Went from about 50 to 35 with same decrease in power through throttle. Just feels sluggish.
 

boudin

Jet Boat Addict
Messages
312
Reaction score
245
Points
122
Location
Lake Livingston, Texas
Boat Make
Yamaha
Year
2008
Boat Model
AR
Boat Length
21
A recap of what you've done:

1. New CR9EB plugs
2. Removed the air filter--was oil soaked?
(this alone fixes many VX issues)

3. Swapped injectors with a known running ski. (eliminates a clogged injector and a loose injector plug)
4. Checked compression... >164psi in each hole?
5. What else?

-Greg
 

Pinhacker71

Jetboaters Lieutenant
Messages
383
Reaction score
251
Points
167
Location
Verona, KY
Boat Make
Yamaha
Year
2015
Boat Model
242 Limited E-Series
Boat Length
24
New plugs
Air filter was soaked. Removed some oil and removed air filter. Ski ran good when I discovered the soaked air filter. Didn’t bog down until about 30 min running after I removed it.
Swapped injectors. No difference
Swapped coils. No difference.
Swapped batteries and rectifier. No difference.
Pulled pump, impeller looks good and space between wear ring looks good. Sealed pump just to make sure no gaps. No difference.
All plugs spark when start with grounded to engine.
Compression good in all cylinders.
Tech at Yamaha dealer said it sounds great and can’t hear it missing or any issues.
 

boudin

Jet Boat Addict
Messages
312
Reaction score
245
Points
122
Location
Lake Livingston, Texas
Boat Make
Yamaha
Year
2008
Boat Model
AR
Boat Length
21
Sanity check: This is a Deluxe right? Are you somehow in SLO/Learner mode? What is your max RPM?

If not, then yes, swap fuel sending units next.

-Greg
 

Pinhacker71

Jetboaters Lieutenant
Messages
383
Reaction score
251
Points
167
Location
Verona, KY
Boat Make
Yamaha
Year
2015
Boat Model
242 Limited E-Series
Boat Length
24
Didn’t come with remote. Learner mode is not illuminated and 7000 rpm. My understanding is learning mode is lower rpm than that.
 
Top