2000 Sea Doo RX 951 Carb sputtering with jumping rpms

[NCGator25]

I have a 2000 RX with a 951 Carb engine. I rode it two weeks ago and it ran perfectly. This was after installing a new battery cables with an anderson connector so I can disconnect more easily. I also had the carb off at that time in order to replace the fuel accelerator lines. I checked the carb filters and they were fine. It ran great after these changes.

However, when I took it out today, it was sputtering and what I assumed was misfiring. I thought it might be a little water in the gas (I use red Stabil) but it never got any better.

While idling, it would jump from 1000 rpms to 2050rpms. It would do the same thing at higher rpms as well if I tried to give it some gas.

After 15 mins or so trying to run the bad gas out of it, I took it out of the water. At this point, I don't think it's the gas, but I'm not sure what I should be looking for. I pulled the spark plugs and they appeared a bit fouled to me. They've been brown in the past.

Any ideas on some initial troubleshooting steps?

 

[NCGator25]

Any thoughts out there on what may be causing this issue?

 

[POPPS]

The fluctuation in rpm indicates a lean fuel condition,,,in the carb,,,or an air leak at the carb base gaskets,,,(very easy for them to fall off),,,even the accelerator pump perhaps...

 

[NCGator25]

Thank you! I wasn't aware a lean condition can cause the RPMs to jump. At least that gives me a starting point of where to start looking. When I had the carbs off last time, I did change the gaskets since the paper ones I had on there had a tear in them.

I haven't been able to find a lot on this condition in my searching, so I'll post back once I'm able to find the problem(s).

 

[FL-Rider]

You mentioned it ran good two weeks ago but you had a concern there might be water in the gas now... Did something happen since two weeks ago that could have allowed water to get in?

 

[NCGator25]

No, it's been sitting in my garage since then. The water in the gas is the only thing I could think of at the time, but I was in the cove running it for roughly 15-20min at idle and lower RPMs thinking I could run the bad gas out of it, but it didn't improve. I had also just topped off the tank with 7 gallons, and additional Stabil (red), so I kind of ruled out water in the gas since it never improved.

 

[POPPS]

If i were you...i would bypass the fuel selector,,,and remove the carbs again,,,and go thru them with a fine toothed comb.

 

[Boyd12]

What do the spark plugs look like? Lean? Rich?

 

[NCGator25]

Actually, they looked a little on the rich side when I checked them at home. Black and a bit wet. I'm going to work on the ski today.

After doing some additional reading on the symptoms I was having, I plan on draining some of the fuel first, to ensure I don't have water in the gas. Then, I'll remove the carbs if the gas looks fine. I have some new base gaskets that came in yesterday, so I'll install them as well.

 

[POPPS]

Try this,,,dump a couple cans of gas line de-icer into the tank,,,let it mix,,,the deicer will brake up settled water,,,see what happens...

 

[Boyd12]

If Sta-bil doesnt do it, nothing will.
If you did not buy gas during the time it sat, how could water get into the fuel?

 

[NCGator25]

Update: I worked on the ski all weekend.

On Saturday, I did the following:
1) Attempted to siphon some gas off the bottom of the tank, but the transfer pump I bought wouldn't work, so I wasn't able to get that done.
2) Took the carbs off and checked the filters (were clean), and reset the low speed needles. Everything else looked good, and didn't see any issues with them.
3) Changed the carb base gaskets with the ones I got from OSD. Much better quality.
4) Battery topped off with trickle charger. Fully charged.
5) Cleaned RAVE valves. They were pretty dirty considering I'd just cleaned them up last Aug. when I bough the ski.

Put it in the water, and it seemed to be running good initially. It was idling too high, so I back off the idle screw, but it continued to do it, so I'd decided I'd adjust the throttle cable when I got home. After getting it out into open water, it took off, and was easily doing 30-40mph. After letting it warm up a bit, I gave it the beans, and it took off. However, when letting off the throttle, it lost power, and began misfiring/jumping rpms again.

Another issue arose too. It seemed to have trouble starting. Very little power getting to the starter. One time, it beeped and the maintenance light flashed quickly. Thankfully, I was able to get it started, so I took it in and put it on the trailer.

On Sunday, I did the following:
1) Pulled the spark plugs. See pictures for condition 24 hours after it was in the water. Put new spark plugs in it.
2) Adjusted the throttle cable. Shouldn't be good now.
3) Wire wheeled the terminals on my anderson connector for the battery lines, ground wire, and starter wire. These are all brand new as I replaced them all when I installed the anderson connector. Used marine wire. They had some solder left on the ends, so I wanted to make sure it wasn't causing any issues.
4) Took the fuel sender out, and pumped out a half gallon off the bottom of the tank. See picture. The gas looked fine and didn't seem to have water in it.
5) Checked the fuel filter. A little sediment, but nothing that should cause an issues.
6) Put everything back together.

Now, it won't start! Even tried dropping a little pre mix in the cylinders, and it wouldn't fire. Not sure if the fuel sending unit is all the way back on. There is pressure in the fuel system, because when you un-srew the fuel filter, you can hear air escape. Checked all of the fuel lines to make sure I put them back correctly.

Racking my brain trying to figure out why it won't start.

 

[NCGator25]

Worked on the ski again tonight. I wasn't able to get it started. I took the carbs off again, and it turns out I put one of the gaskets on backwards, so I fixed it.

I also bought a spark plug tester and it appears I'm getting spark, but on the rear cylinder, the light doesn't come on immediately. There seems to be a hesitation. I wonder if a bad coil would cause the issues I'm having. ie. if the plugs aren't providing a constant ignition source.

It won't start even if I put premix directly in the cylinders.

I also bought a Innova compression tester. I'm reading about 100psi on both cylinders. When I tested it last year, it read 135psi. I've only put 30 hours on the ski since then. It has a total of 150 hours on the ski now.

Any thoughts on other items I should be testing. Getting frustrated! Just can't understand how the ski went to crap after sitting in my garage for two weeks!!!

 

[POPPS]

100 seems low,,,and I believe DI's cut out the rear spark at idle to save fuel

 

[NCGator25]

Yeah, I'm going to get another compression tester and check it again. The one I bought was from Autozone, but I'm not sure of the quality of it.

This is a carb model, so I'd imagine the spark should remain constant. I'm researching how to test the coils tonight, so I can check them another way instead of just using the spark tester I bought.

 

[Grim]

You could always just borrow AutoZone's compression tester, they rent them out.

 

[NCGator25]

I just rented one from O'Reillys this morning. For some reason, I can't get a reading on it at all. The needle bounces with each compression, but I'm not getting a reading.

Also, the engine doesn't seem to be creating the suction needed to pull the gas into the carb. The gas feed line was empty when I checked it. As a test, I bypassed the selector and it seems to be getting gas to the carb when it's feed directly into the carb.

I put the gas selector in the ultra sonic cleaner.

I basically have everything apart again today trying to trace down what might be causing the issues!

 

[NCGator25]

Now this is weird. I was just checking the cavities where the reeds are located, and I saw this o'ring sitting in the front cavity around the oil port!

Any ideas on what this o'ring is for?

I think I'm going to pull the reeds out to check them while I have everything off.

 

[NCGator25]

The reeds seem to be fine, but they have what I'd consider more oil on them than necessary. I tried taking a photo, but the oil isn't showing up on the photos.

I'm looking through the parts doc, and I can't seem to find what that o"ring might be for, or why is was sitting in the "reed chamber."

 

[NCGator25]

I've put everything back together, and it still won't run. I checked the compression again, and I'm getting 110psi. The tester from O'Reily's didn't have a schrader valve in it.

Any ideas on next steps would be appreciated. I'm lost as to what to do or test next.

 

[NCGator25]

Any thoughts on where that rubber seal may have come from? I've looked through the parts manual, and can't find any seal similar to it.

 

[NCGator25]

Update: I was to get it running again. In the end, I think the loose spark plug cap was causing an intermittent spark, which caused the jumping rpms/sputtering/misfiring issue that started this whole 15-20 hour journey to find the problem.

I'll try to get it on the water tomorrow after work.

Thanks for all the help!

 

[tomanycars]

So what’s going on with the ski. Is it running.

 

[NCGator25]

As it turns out, I think there were several issues that were going on with the ski at that time. The start/stop button was malfunctioning, spark plug cap mentioned above, and it was running very lean.

In the end, I burnt a hole in the piston, which kicked off a full engine rebuild.

After having someone rebuild the engine, I got 15 hours out of it before having to pull the engine again. There was water getting into the cylinders under the head gasket. I'm going to have to rebuild the top end again, but I'm hoping I don't need to buy new pistons, etc. I'm hoping it'll just need a seal kit so I can put everything back together. Still have work to do to figure those things out.

Buy a jet ski they said....it'll be fun they said!!! Been a money pit so far, but I do enjoy working on it.

 

[Boyd12]

As it turns out, I think there were several issues that were going on with the ski at that time. The start/stop button was malfunctioning, spark plug cap mentioned above, and it was running very lean.

In the end, I burnt a hole in the piston, which kicked off a full engine rebuild.

After having someone rebuild the engine, I got 15 hours out of it before having to pull the engine again. There was water getting into the cylinders under the head gasket. I'm going to have to rebuild the top end again, but I'm hoping I don't need to buy new pistons, etc. I'm hoping it'll just need a seal kit so I can put everything back together. Still have work to do to figure those things out.

Buy a jet ski they said....it'll be fun they said!!! Been a money pit so far, but I do enjoy working on it.

"There was water getting into the cylinders under the head gasket." I have had that issue before. Please keep us posted if you dont mind!