951 GSX Fuel delivery problem.

[Weebage]

Hello, I have a 1998 GSX limited, it doesn't run good at all, it dies when you hold the throttle open for more than 5 seconds, does this at full throttle and mid throttle... then bogs until the fuel pressure builds back up then does the same thing. It also dies when you punch the throttle at all, if you jam it open and shut really fast then it'll go. When it hits the power band for that split second it's got power and sounds great too. Pulled plugs when it died and they were dry, not soaked, which makes me think it's fuel related. Plugs are tan mocha colored.

Here's everything I've tried to do to fix it.---

Previous owner put new lines on it, which are all in the correct spots.

Checked the pressure check valves on the tank, I think they're ok but ordered new ones in cases

Haven't taken the fuel line from the filter to the carb off but all the other lines are clear.

Rebuilt carbs with OSD back to OEM kit. New needles and seats, all jetting was out to stock, I believe it was 1 1/4 on low speed and high speed was 0 on mag and 1/4 on PTO. I followed the diagram from mikuni as best I could. Accelerator pump has new lines that I put on, 7/16 lines, diaphragm was good and pumped fuel. I went thru the entire carb with carb cleaner and air chuck. Filters were clean and replaced.

New fuel filter o ring and filter.

New coil because it was bouncing off the limiter sometimes and sometimes it didn't, after I replaced the coil I started having this new "fuel related?" issue but I don't believe it's spark related, I'm not 100% sure.

I haven't taken the fuel baffle out yet but I was going to blow air thru the top, because it seems like a pain to get it out.

At this point in time the ski will not pump its own fuel, I can blow air and pressurize the line but once it runs dry it will not start. I checked the inline fuel filter and it had barely any fuel in it.

I have no idea what the problem could be, I've been doing research and read something about restricting the return line? Never heard of that but I'm stumped, I'm tired of throwing parts at it. Any help would he greatly appreciated thanks!

 

[tobytd]

951 fuel lines are 5/16. If I’m reading correctly 7/16 lines may be sucking air

 

[Weebage]

951 fuel lines are 5/16. If I’m reading correctly 7/16 lines may be sucking air

Ya know what I think they are... I think I did actually put 5/16 on only because I reused the original fitting and it was really tight. But I'll double check thanks!

 

[mikidymac]

Couple thoughts.
Did you follow the carb rebuild sticky with those OSD kits?
I would try bypassing the fuel selector, go directly from the fuel tank to the carb and see if it pulls fuel. The selectors are notorious for going bad.

 

[Weebage]

Couple thoughts.
Did you follow the carb rebuild sticky with those OSD kits?
I would try bypassing the fuel selector, go directly from the fuel tank to the carb and see if it pulls fuel. The selectors are notorious for going bad.

I followed the diagram that comes with the OSD kit to the t, that put it together the same way it came apart.

I'll try that thanks

 

[mikidymac]

I would review the carb rebuild thread to check everything. You really need to test pop-off and leakdown.

 

[Ditch1000]

Double check for a leak; I just went through this on my 1998. The small line from fuel assist pump was pinched by the bottom carburetor bolt on the PTO carb and rubbed a 1/8” hole in the line. I had to install new lines on that circuit.

 

[mikidymac]

Also if you replaced the 1/8" feed line for the accelerator pump I hope you reinstalled the restrictor jet that is inside the factory hose. Without that the pump will not work correctly and could cause a bog.

 

[Weebage]

Also if you replaced the 1/8" feed line for the accelerator pump I hope you reinstalled the restrictor jet that is inside the factory hose. Without that the pump will not work correctly and could cause a bog.

Oh goctha ok I did not, I kept the hoses I'll try to find it thank you.

 

[Weebage]

Double check for a leak; I just went through this on my 1998. The small line from fuel assist pump was pinched by the bottom carburetor bolt on the PTO carb and rubbed a 1/8” hole in the line. I had to install new lines on that circuit.

Oh man good catch, ill go thru and triple check everything thanks

 

[Ditch1000]

Also if you replaced the 1/8" feed line for the accelerator pump I hope you reinstalled the restrictor jet that is inside the factory hose. Without that the pump will not work correctly and could cause a bog.

I have both a 1998 and 1999 GTX Limited Edition; I just checked the old lines that I still have on the bench and there is no restricter in either of them.. Could the restricter be built into the “T” fitting?

 

[mikidymac]

I have both a 1998 and 1999 GTX Limited Edition; I just checked the old lines that I still have on the bench and there is no restricter in either of them.. Could the restricter be built into the “T” fitting?

It is one of those strange Seadoo mysteries. In all these years I have never figured out why some have them and some don't. Also why some are shown on the parts diagrams and some are not even when the ski may or may not have them.

Only guidance I can give is if it had them then put them back in or it will not run correctly. If it never had them don't worry about it.

 

[Weebage]

It is one of those strange Seadoo mysteries. In all these years I have never figured out why some have them and some don't. Also why some are shown on the parts diagrams and some are not even when the ski may or may not have them.

Only guidance I can give is if it had them then put them back in or it will not run correctly. If it never had them don't worry about it.

They gotta make everything difficult

 

[Ditch1000]

It is one of those strange Seadoo mysteries. In all these years I have never figured out why some have them and some don't. Also why some are shown on the parts diagrams and some are not even when the ski may or may not have them.

Only guidance I can give is if it had them then put them back in or it will not run correctly. If it never had them don't worry about it.

I doubled checked my lines; the only line I didn’t replace was the line from the diaphragm cover to the accelerator pump. I believe thats where the restricter is so I didn’t want to mess with that part and it looked fine so I left it.

 

[Weebage]

Finally found some time this week, it's been a crazy one... I never replaced the line that had the recharge jet but the previous owner did. And the jet was not in the line. So I took one out of a parts carb I had laying around (not 951 but same pump) and put it in, also on that set of carbs, off a 1998 speedster with twin 787s, has a green and white check valve on the line going from the accelerator pump to the T fitting, my 98 GSX did not have that. Im wondering if it's back feeding fuel or pressure?

 

[mikidymac]

787 carbs are different than 951, don't change the 951 carbs to match.

 

[Weebage]

787 carbs are different than 951, don't change the 951 carbs to match.

Ok the part numbers on the recharge jets are the same, 951 and 787 carbs but I won't mess with anything else.

 

[Weebage]

Ok finally got this thing on the water, I blew out all the hoses and fuel baffle with air. bypassed the selector ran directly to reserve. Put those new check valves on as well as the recharge jet. Removed the bog I experienced at idle to full throttle. It still has a gargle mid power band then still dies after 5 seconds. I found out the nipple on the return line is cracked and I'm going to attempt to repair it, it was bubbling the fuel around it while running so my guess is that's the air leak I'm looking for? If I let it idle for about 10 seconds (it idles great) then I can punch it again for 5 seconds then dies, if I don't wait it bogs and bogs until I let it idle.

My other guess is reeds. Maybe they aren't sealing and sending pressure thru rather than creating vacuum but I feel like if they were bad it would run good at all.

 

[mikidymac]

Fix the leak and retest.

 

[Weebage]

Fix the leak and retest.

Yup

 

[Weebage]

I think I found the problem... Found a forum where the guy drilled that plastic TEE out and tapped in a brass t, did that and no more leak... Took it out on the water and the same thing happened. I blew into the vent line and can hear air leaking, looks like it's coming from the fuel baffle, one of the plastic fuel barbs. It's blowing out fuel and air. Any tips on getting that out? I believe u gotta take the handlebars off?

 

[tobytd]

Tank unstrapped moved as far forward as possible?

 

[Weebage]

Take unstrapped moved as far forward as possible?

I think so, im gonna mess with it. seems like it's gonna be a pain, I keep u all updated.

 

[Weebage]

Got the baffle out and found out it's the wrong baffle. Correct me if im wrong but the 98 GSX limited has a baffle with 2 bigger nipples for the fuel output, this baffle had all the same size but the smaller nipples. Gonna grab one of my buddies parts machine and swap it over.

 

[mikidymac]

It should be 5/16" fittings as far as I know.