1995 SeaDoo SPX - Carb not getting fuel

[Lothsahn]

should i blow it out through the return valve? or from the other side, somehow?

To be clear, you have the fuel inlet/return plate off the carb, or installed? If it's installed, I would expect that you may not be able to blow through the return, because the fuel pump has two check valves (actuated by the pulse diagrapham), and the only other path is through the needle valve, which has a spring on it.

If you have the fuel inlet/return plate off, it should not matter which direction you blow. As you can see, there's just a restrictor in the diagram linked by @Ckrawiec.

 

[Lothsahn]

Ok....here's a couple pics.

The return valve is the one with the 90 degree angle. That is the one I can not blow air through.

If I should be able to, I am not sure how to clean it out and what hole connects to the return. I can easily tell the inlet comes oit of the bigger hole, but I'm not sure where the return is fed from.

I'm going to have to let someone with more experience speak. I don't recognize that plate at all. The ones I've always seen have both of the fuel hose attachments on the same side, as shown here:
http://www.2040-parts.com/_content/items/images/22/946222/004.jpg

Maybe this is a special plate for the PTO carb in 1995? Or maybe someone's swapped a different carb?

 

[kenkuntz]

To be clear, you have the fuel inlet/return plate off the carb, or installed? If it's installed, I would expect that you may not be able to blow through the return, because the fuel pump has two check valves (actuated by the pulse diagrapham), and the only other path is through the needle valve, which has a spring on it.

If you have the fuel inlet/return plate off, it should not matter which direction you blow. As you can see, there's just a restrictor in the diagram linked by @Ckrawiec.

That is correct. I have the plate off....tried carb cleaner and 90psi air compressor...to no avail! Seems like I need a flexible boring bit....haha.

No idea what to do at this point....

 

[mikidymac]

Yes air and carb cleaner should flow in all directions of that. There is a smaller restrictor orifice in it but it needs to let air and fuel through.

 

[kenkuntz]

Update:

I was able to get the return line cleaned out finally. Still having problems getting gas into the carbs.

What I did was disconnect the return line and crank the engine. I am now seeing gas come out of the return outlet. So, I can see gas flowing through, pump appears to work, check valves, etc.

So....what's my next test? It feels like the needles are not releasing gas into the carb, but we've rebuilt this several times with new parts. Currently set the popoff at 16psi (low end of service manual recommendation), because I didnt have other springs to get it up any higher.

1 late observation by my assistant (father)....when we just took off the carbs, apparently we had failed to tighten down the bolts that hold the carbs to the engine. So, they were only hand tight. Question, assuming this is causing air to be sucked in, would this have a direct affect on my current problem? I wasnt sure if the popoff needle pressure is building from fuel pump, or a suction/pressure from the engine cranking.

 

[Lothsahn]

My understanding is that air leaks in the engine will cause a lean condition, where not enough fuel gets pulled in because the engine is sucking outside air that contains no fuel (bypassing the carb).

A low popoff pressure should cause the mixture to be too rich (too much gas), especially at lower throttle settings.

You said you feel like it's still not releasing gas into the carb. Why do you think this? Is your choke cable hooked up and working on the carbs? I need to pull choke (and sometimes, give a little throttle) to get the engine running. Giving throttle can be especially important if you haven't yet adjusted the idle adjustor.

Are you running the test with the backfire suppressor and airbox cover on? It's important for the various air pressures to have the entire system assembled when you test (although you can leave out a few bolts holding on the backfire suppressor while you test).

If you know that you're seeing gas come out of the return, that means the fuel pump is working in the mag carb. Are you sure that your high and low nozzles are clean and able to release fuel? If you spray carb cleaner in the high & low jets do you see it come out the center of the carbureator?

Did you set your adjustment screws to 1 1/8 turns out (Low) and 0 (fully in) (High). Turn the adjustments gently--they don't require a lot of force, and they're small precision parts so you don't want to force them.

Here's the video that really helped me with my carb rebuild:

I'm really concerned about your statement that it's 16 psi because you don't have other springs to get it higher. You have to use the right weight spring, which typically puts your popoff almost smack dab in the middle. If you don't have the right spring, you can't get the popoff to work right. See this post: Carburetor pop-off pressure????

Do you have the original springs before you rebuilt the carbs? It might be best to use those. I also don't know which popoff pressures you should aim for (given the difference between the reference guide and service manual), but I'd go with the service manual numbers.

My heart goes out to you. I know this has to be frustrating. I hope you get it soon!

 

[kenkuntz]

ok....hopefully a good update.....

So, it is now working. Yes, i did set the high/low speed screws accordingly when i rebuilt the carb. Using the Seadoo Service manual, I bought the springs that are supposed to go with the carb/engine. The service manual said 16-21 psi......with the given springs, I was at 16psi each carb.

Ultimately, I think I had 2 problems.
1 - rebuilt carbs with correct Mikuni parts, needles, springs, etc.
2 - there was a clog in the return of the PTO carb

Now that is running, I tuned the idle RPM to 3000. I'm not sure what else needs tuned at this point, but I was thinking the next step was to take it for a ride and see how it does.

 

[Lothsahn]

ok....hopefully a good update.....

So, it is now working. Yes, i did set the high/low speed screws accordingly when i rebuilt the carb. Using the Seadoo Service manual, I bought the springs that are supposed to go with the carb/engine. The service manual said 16-21 psi......with the given springs, I was at 16psi each carb.

Ultimately, I think I had 2 problems.
1 - rebuilt carbs with correct Mikuni parts, needles, springs, etc.
2 - there was a clog in the return of the PTO carb

Now that is running, I tuned the idle RPM to 3000. I'm not sure what else needs tuned at this point, but I was thinking the next step was to take it for a ride and see how it does.

Glad to hear it! Keep in mind it will idle far lower in the water, but that's normal. Go get it wet and (hopefully) have some fun!

 

[kenkuntz]

Latest status:

I can start the ski, but only with the choke pulled. It will die if left idling, unless choked. Popoffs were set around 16psi, as per one of my earlier posts.

I was able to full throttle it and fly down the river. Seemed to work great at high speeds. So, looks like some adjusting needed for the idle/low speed.

Any recommendations? Does my popoff need adjusting too?

Also, I have VTS that does not seem to do anything. Troubleshooting steps? Does the switch rot out before the motor, or am I looking at a new VTS motor? And does the trim typically need played with when riding?

The kill switch keeps popping off from vibration, so I just ordered a new one.

Im close!

 

[POPPS]

ok....hopefully a good update.....

So, it is now working. Yes, i did set the high/low speed screws accordingly when i rebuilt the carb. Using the Seadoo Service manual, I bought the springs that are supposed to go with the carb/engine. The service manual said 16-21 psi......with the given springs, I was at 16psi each carb.

Ultimately, I think I had 2 problems.
1 - rebuilt carbs with correct Mikuni parts, needles, springs, etc.
2 - there was a clog in the return of the PTO carb

Now that is running, I tuned the idle RPM to 3000. I'm not sure what else needs tuned at this point, but I was thinking the next step was to take it for a ride and see how it does.

Idle speed, 2500 on trailor, 1500 in the water, for non jetboats.
When setting up any 2 stoke, set the low speed pilot circuit first, it should be able to take throttle without any lean bog, then you can adjust the high speed circuit, which on a seadoo, the highs are fully closed anyway.

 

[claysimo]

Were you able to clear it out? Id just blow compressed air through the holes after spraying carb cleaner till you can blow it through. Either clogged or pinched