1999 XP Limited Fueling Issue

[SeaDooDoo90]

The hoses were only replaced last month so those cannot be the issue, though I will still check them to ensure they have a good purchase on each nipple. I've already ruled out the fuel selector isn't the problem as I temporarily bypassed it and nothing changed. My fuel strainer has a fresh seal too so I don't think that's it.

Definitely does sound like a fuel system leak somewhere and the most likely culprit at this point I think is the pump. Either that, or the pickup, but I didn't think that part was prone to failure.

My fuel return line has a zip tie on the nipple so I'll put a clamp on there to see if anything improves while I await the pump rebuild kit.

As an aside, I'm rebuilding a set of SBN-44's right now and from Mikuni's instructions, just learned there is a proper orientation for the check valves in the fuel pump. I assume the BN-46I's off the 951 are the same way, and if so, odds are at least one of the two are installed incorrectly.

 

[mikidymac]

Yes, the pump disc's have the same orientation as the other Mikuni carbs.

 

[SeaDooDoo90]

I finally reached a conclusion on this and the issue is now fixed. I did install a genuine Mikuni fuel pump rebuild kit, mainly to ensure my check valves were each oriented correctly, but this did not fix the issue.

Turns out my issue was a combination of a bad fuel selector switch and loose hose clamps on the pickup (doh!). So, while I did temporarily bypass the selector switch to test this part earlier in the summer, it didn't isolate the problem because the fuel lines didn't have a good seal.

I followed this helpful guide on PWCToday, which is similar to one of @FL-Rider's troubleshooting ideas he recommended in this thread, and sure enough, there were lots of bubbles in my fuel inlet hose and I could not get a good siphon going.

After installing a used OEM selector switch, which has a far more positive detent between each of the three positions than the old one, and tight hoses on the baffle, the ski is running great.

This is the quickest ski I've ever rode. What a machine!

Just curious - what position of the VTS will yield the highest top speed? I had it aimed slightly down (roughly 3/8 if it were reading as a fuel gauge where 1/2 is a flat trim). I topped out at 58 MPH on a GPS speedo, whereas I thought these skis were good for the low 60's.

 

[mikidymac]

I would really caution you about used selector valves.
You can get new good ones from WSM Part Number 006-604 and PWC Muscle does offer some forum discounts on WSM parts. They are about $50

Highest top speed would be on glass with it trimmed all the way up before it starts bouncing to get as much of the hull out of the water as possible but I typically run mine in the middle 99% of the time.
Your ski should radar at 61 mph as it was the fastest stock 2-stroke of the day.

 

[SeaDooDoo90]

Thanks - good to know about the WSM part. I could only find aftermarket ones for this ski and learned my lesson on that on my '95 XP. I'm gonna run the used one for now but will keep that in mind.

Cool! I will adjust the trim up a little. Makes sense to get as much hull above the water as possible, which my prior position definitely did not do. Maybe I can squeak out those additional 3 MPH this way.

 

[mikidymac]

Sadly, Seadoo had been discontinuing a lot of the common maintenence items on these lately. Once I use up my stock I guess we are just going to have to go trial adn error on the aftermarket stuff.
Been using that WSM one for 5 years not on my 01' XP with no issues.

 

[SeaDooDoo90]

Victory on this one was short-lived. My friend and I were able to log maybe 30 mins of trouble-free riding before the issue reared its ugly head again. For those 30 mins, it was running like a top. Zero issues at all.

My buddy claims he submerged the bow in a wave, came back up, had another couple seconds of good power delivery and then it flopped. It's now back to its old ways and it's actually running even worse. It bogs down and has a hard time getting past 3000 RPM now.

First thing I did was pull the plugs and crank over. Thankfully, no water blew out. The plugs, however, were wet with water (I confirmed this by trying to light the tips on fire and they did not ignite).

I'm starting to wonder if my problem is water ingestion. I understand the XP hourglass hull is notorious for this. When addressing the fuel system earlier this month, I had the ski out of the water for about 10 days in a high desert climate (very dry air). I'm wondering if that stint was long enough to evaporate any water in the engine, so when I launched it again last Thurs, it ran great. I was riding on glass and did not do anything to dive the bow, so under the hood did not get serious water exposure during that time. A couple days later, my friend takes it out, and it runs great until he submerges it. I can confirm the airbox had a little water in it this time around (maybe a half ounce), and I've noticed water in it previously too.

Are my symptoms consistent with water ingestion? If so, what can I do to pinpoint the ingress?

Lastly, I have the seat off to access the fuel pickups and troubleshoot. When riding, especially at higher RPMs, there are tiny streams of water pissing out of these two elbow fittings above the tank. It looks like there are intentional pinholes in them. I can't imagine this has anything to do with my root problem, but I'm curious if this is normal?

 

[mikidymac]

It sounds more like something electrical is getting wet than actual water ingestion.
What makes you think your plugs have water on them? Do you actually see a drop of water bridging the gap?


Yes, those elbows are supposed to have the hole. Jet s of water should never be spraying out of them, if there is then the white straws inside the jet pump nozzle are missing and water is being forced into the hull instead of pulling it out. This will cause the hull to flood with water.

 

[SeaDooDoo90]

It sounds more like something electrical is getting wet than actual water ingestion.
What makes you think your plugs have water on them? Do you actually see a drop of water bridging the gap?


Yes, those elbows are supposed to have the hole. Jet s of water should never be spraying out of them, if there is then the white straws inside the jet pump nozzle are missing and water is being forced into the hull instead of pulling it out. This will cause the hull to flood with water.

Correct, one of the plugs had a drop of water in between the gap. And also, a little water in the airbox. It was never enough for me to think it could cause an issue, but now I'm not sure.

My CDI box is properly sealed and I just verified it's completely dry inside.

Got it - I figured that couldn't have been normal and is at least part of the reason it takes on water. I didn't think this ski had a siphon bilge since it has the electric one, but sounds like those elbows are part of the siphon system? Are the straws I'm missing in the parts diagram below?

 

[FL-Rider]

 

[mikidymac]

View attachment 63905

Yes! Those are the siphon tubes. Thanks for the great picture.

 

[SeaDooDoo90]

Thanks for the help, guys. I cannot verify for certain since this ski is at my parents' place right now, but I believe I am missing those.

Anyone have a part #? I do not see them in the diagram above.

 

[pantaloonz]

Did you ever resolve this issue? - I just traded away my 99 gtx that has similar problems.
It was a nice fair trade, if you did resolve this I'd share it with the person I traded too.

-pantz

 

[SeaDooDoo90]

I have not reached a conclusion yet. I've tested every component individually in the fuel system and everything checks out (including hooking the fuel pickup directly to the carb and bypassing the filter and selector switch, which did not improve anything).

I know for a fact I did have a fueling issue at some point as I couldn't start a good siphon with the old fuel selector switch, but replacing this part didn't solve the issue. My current theory is still water ingestion. From what I've read, the 947 is extremely sensitive to any level of moisture within it, seemingly more so than your typical marine 2-stroke.

I still need to fix the siphon elbows pissing inside the hull, which certainly can't be helping matters. I will update this thread as I make further discoveries.

 

[SeaDooDoo90]

Can anybody assist with a part # on these siphon tubes? I'm seeing there are both short and long ones for a 155 pump.

Short = 271001133
I cannot find the long version part # and am unclear on which one the XPL takes.

 

[burtshaver2021]

I have not reached a conclusion yet. I've tested every component individually in the fuel system and everything checks out (including hooking the fuel pickup directly to the carb and bypassing the filter and selector switch, which did not improve anything).

I know for a fact I did have a fueling issue at some point as I couldn't start a good siphon with the old fuel selector switch, but replacing this part didn't solve the issue. My current theory is still water ingestion. From what I've read, the 947 is extremely sensitive to any level of moisture within it, seemingly more so than your typical marine 2-stroke.

I still need to fix the siphon elbows pissing inside the hull, which certainly can't be helping matters. I will update this thread as I make further discoveries.

Are you still running the venom kits in the carbs? I’ve read a lot of posts where the aftermarket kits didn’t work.

 

[SeaDooDoo90]

Are you still running the venom kits in the carbs? I’ve read a lot of posts where the aftermarket kits didn’t work.

The carbs still have the Venom rebuilds. The fuel pump was rebuilt with genuine Mikuni, ensuring I had the check valves oriented correctly.

I really don't think it's a carburetion problem though. The ski ran like a bat out of hell for a good 30 mins once I solved the fuel starvation issue from a bad selector switch. Then the bow gets badly submerged, and it immediately shits itself. It can't be a coincidence.

 

[burtshaver2021]

The carbs still have the Venom rebuilds. The fuel pump was rebuilt with genuine Mikuni, ensuring I had the check valves oriented correctly.

I really don't think it's a carburetion problem though. The ski ran like a bat out of hell for a good 30 mins once I solved the fuel starvation issue from a bad selector switch. Then the bow gets badly submerged, and it immediately shits itself. It can't be a coincidence.

I’ve been following along but forgot about that happening, hopefully you can get it figured out and get some enjoyment out of it. Just looking at the weather and it looks like tomorrow is the end of our hot spell around here.

 

[mikidymac]

Is your MPEM in the nose of the ski or up high on the side wall?

Seadoo found that the ones in the nose were getting wet and corroding the connectors so they blocked off the nose air inlets and moved the MPEM's high up on the side wall but I don't remember what year the change was.

If it cuts out when the nose gets under this could be it.

 

[SeaDooDoo90]

Is your MPEM in the nose of the ski or up high on the side wall?

Seadoo found that the ones in the nose were getting wet and corroding the connectors so they blocked off the nose air inlets and moved the MPEM's high up on the side wall but I don't remember what year the change was.

If it cuts out when the nose gets under this could be it.

Interesting thought. I'll need to verify when I'm at the ski again. I know my CDI box is in the starboard-side of the bow, pretty low down, but I don't believe the MPEM is in this housing.

I also remember reading about SeaDoo plugging those two inlets at the bow. I believe they did that starting in year 2000. On my ski, they're open and connect to two tubes that go down into the hull. I recall reading about a modification to block these off on the 98/99's with no penalty to intake breathability.

I also still need to determine which siphon tubes my pump is missing. Unsure if I need the long or short ones. Somewhere else on the forum, a member confirmed their '99 GTX uses the long ones, so that may be where I start

 

[SeaDooDoo90]

Got to my ski last night and confirmed I am indeed missing the white siphon tubes. No surprise since the guy who "rebuilt" this ski and my SPX's pumps is a joke and there are numerous parts he left out. Add one more to the list.

I also confirmed the location of my MPEM which thankfully is not in the problematic bow area, but high up on the wall on the port side. That said, this is in the area of where the two siphon tube elbows are incorrectly pissing. It seems entirely plausible this spray could interfere with the electronics in this area of the ski.

Can anyone help with a part number on these siphon tubes? BRP doesn't list them in their catalog!

 

[SeaDooDoo90]

UPDATE: Apparently BRP forgot to list this part for the XP in their 1999 catalog, but starting in 2000, it's included.

Part number is 271001133 which looks like the easier of the two versions to source.

What is the recommended way to adhere these into the pump? Marine epoxy? Silicone? I imagine they have to be quite secure since they're constantly getting jet blasted.

 

[mikidymac]

I have never has them out but I would use a little epoxy.
Also make sure you clean all the mpem connections and use a little DI-electric grease.

 

[Grim]

I had one missing on my 98, I test fit it in and with some light tapping it went in and wasn't coming out...easily. So thats how I left it, been over 15 hrs on it and still there.

 

[SeaDooDoo90]

Thanks guys. I'll use a touch of epoxy just to ensure they don't go anywhere