Air bubbles in fuel lines

[mejim707]

I have a 96 Seadoo challenger with the 787 engine. While working on other things tonight I noticed the two fuel lines that run across the top of the carbs under the air box have air in them. I’ve had this thing down at the lake running around a few times and it seemed to run well but this air in those two small lines after the ‘Y’ splitter concerns me.

Is this normal or should I get this out? If so does anyone have suggestions on what to do / how?

Thanks a lot!

 

[mejim707]

I found an old thread I’m looking over, and checking the parts diagram it looks like these are return lines with the air bubbles in them. Wondering if that’s going to cause a problem. I’ll keep digging in.

 

[mejim707]

One thing I noticed, it that it looks like the previous owner replaced the water separator / filter to one that looks similar to the oil filter. It's an inline unit and does not look like the part 275500088 from 1996 Sea-Doo Challenger, 5896 Fuel System 5896 | Fox Powersports Sea-Doo Partshouse.

It looks more like this,
https://www.amazon.com/SeaDoo-Separator-1991-2002-275000262-275500033/dp/B07P8VXHRC

Could that cause any trouble?

 

[mikidymac]

You should not have air in your fuel lines. You have an air leak somewhere.

You really should get rid of the inline filter and replace it with the correct OEM filter/strainer. THe OEM one is also a water separator that is really important on a marine vessel.

I would also check all hoes clamps and the fuel ON/OFf valve if your boat has one.

 

[mejim707]

You should not have air in your fuel lines. You have an air leak somewhere.

You really should get rid of the inline filter and replace it with the correct OEM filter/strainer. THe OEM one is also a water separator that is really important on a marine vessel.

I would also check all hoes clamps and the fuel ON/OFf valve if your boat has one.

I'll do this tonight. The interesting thing is that I only see the air in the return lines not the supply. The boat seems to run fine, and the fuel in the return lines looks like fresh fuel, but there's definitely air in those lines.

I'll pull the air box tonight to inspect everything further. All of the lines were replaced by the previous owner and look good. I do have a pump pressure tester I can use to test the pressure. I'm looking at the service manual for the procedure and it mentions remove the vent hose and connect the pump to that hose. Is this correct or is there a better way to do this? I also want to pressure test the oil circuit.

If the pressures are correct, how should I go about removing this air form the return lines?

Thanks a lot mikidymac. I really appreciate all of the assistance!

 

[mikidymac]

If it is just air stuck in the return line then try maneuvering the hose to get it up and out into the fuel tank. If it is actually leaking on an inlet hose it might just be accumulating in the return hose.

 

[mejim707]

Welp, this boat is full of surprises I guess lol As I was going over the fuel lines I was taking pictures and saw this gem. Notice how the bolt is not screwed in! This is on the Mag carb.

I ended up pulling both carbs to look them over and check the clenliness of them. Both look great inside so I think that's ok but the fact that they were not screwed down all the way concerns me. This could also be why I was getting some "run away" conditions while running it for a few 15 seconds on the hose.

I also noticed that the fuel line bridging the MAG to the PTO carb was empty of fuel. When I pulled it apart I did see plenty of fuel inside the carb but that fuel line was definitely empty.

I'm going to try and put the carbs back on tonight - tomorrow afternoon if I can find new gaskets.

 

[mikidymac]

Those bolts should have washers on them also.

 

[mejim707]

Those bolts should have washers on them also.

Good call mikidymac! I'll get those in place.

I founbd washers and other screws and whatnot in the bilge area under the engine unfortunately. I think the previous owner, or his mechanic, were drunk any time they worked on this thing. It's a shame but I'm getting er back together and in good shape. I can't stand hacky work!!!

One thing I did find, and I'm afraid to ask this, but about 6 of these 1 inch long pins. I'm not sure what they're for. They're about a 1/16th of an inch in diameter. Any ideas?

 

[mikidymac]

Are the solid metal? Sure sounds like the upper connecting rod needle bearings.
This isn't looking good.....

 

[mejim707]

Are the solid metal? Sure sounds like the upper connecting rod needle bearings.
This isn't looking good.....

I just looked this up, that would be bad... But would the engine run properly if it didn't have the bushings? It runs well from what I can tell. I did have it out running twice and it ran pretty smooth and didn't seem to have any issues revving up.

Without pulling the engine apart to check if the needle bearings are installed, is there some other form of test I can conduct other than simply running it? I would imagine I would hear rod knock if the piston didn't have the needle bearing. Or if it was installed incorrectly.

Man...

 

[JeremyD615]

I don’t think they are needle bearings if you found them inside the hull. At least their not needle bearings out of this motor... The only way for them to get from the inside of the motor to the outside of it would be through a hole in the case, which I would think would be very obvious! Now it is very possible that a top end was done previously and they were dropped in there while they were doing that job...

 

[mejim707]

I don’t think they are needle bearings if you found them inside the hull. At least their not needle bearings out of this motor... The only way for them to get from the inside of the motor to the outside of it would be through a hole in the case, which I would think would be very obvious! Now it is very possible that a top end was done previously and they were dropped in there while they were doing that job...

Thanks Jeremy, whenever I see things like this my mind goes crazy. Like when I saw that bolt loose on the carb last night and ended up pulling them off and doing a teardown and clean on both.

Thinking this is from a needle bearing makes me feel like I need to pull apart the motor just to verify that they're installed lol But I don't see how it could run smoothly if it wasn't. I would think it would knock and blow pretty quickly.

I reached out to the previous owner for some clarification. They said it was running strong on the lake last year, and last time I was out it seemed good to me as well.

I also don't see any holes in the block haha

 

[mikidymac]

Post a picture of the metal parts.

The only way they would be out is if someone pulled the pistons and top end off. There is no way it would be running for more than a few seconds without them and then it would be a catastrophic failure.

 

[mejim707]

Post a picture of the metal parts.

The only way they would be out is if someone pulled the pistons and top end off. There is no way it would be running for more than a few seconds without them and then it would be a catastrophic failure.

These are what I’m talking about

 

[mejim707]

Post a picture of the metal parts.

The only way they would be out is if someone pulled the pistons and top end off. There is no way it would be running for more than a few seconds without them and then it would be a catastrophic failure.

So since I had the carburetors off, to rebuild them, I noticed that one of the oil lines still didn’t have oil filling it up. I decided to pull the oil pump again and run the drill in reverse to pump it to the end.

But I did this before. So I checked the shift that connects the oil pump. If I put a screwdriver in the end of it I can turn it freely. Is that normal? It’s part 23 from this diagram.

1996 Sea-Doo Challenger, 5896 Magneto And Oil Pump | Fox Powersports Can-Am Partshouse

 

[mikidymac]

THose look like piston pin needle bearings. So maybe it had a top end done at some point.

No, you should not be able to turn the oil pump drive freely. It must not be engaging the flywheel bolt correctly or is broken.

You will have to pumm the MAG cover to check it.

 

[mejim707]

THose look like piston pin needle bearings. So maybe it had a top end done at some point.

No, you should not be able to turn the oil pump drive freely. It must not be engaging the flywheel bolt correctly or is broken.

You will have to pumm the MAG cover to check it.

Thanks for the reply and confirmation. Pretty bummed about that. Just trying to muster up the courage and mental energy to lift the engine. I’ve read that you should put a block under the engine and left it 1.5 inches. But there’s all this business about marking a mark on the engine mount and what not and I’m not sure what that’s all about. I need to do more research before I start that part of the project.

I’m just hoping I didn’t do any damage since I ran it a few times for short intervals with apparently the oil not pumping. That sucks. I never heard an overheat alarm and the cylinders weren’t hot so fingers crossed.

 

[JeremyD615]

I wouldn’t pull the motor over that. Those pins could not have come from that motor the way it sits now. Someone probably did a top end on it at some point in the past and dropped them in there...

 

[mejim707]

I wouldn’t pull the motor over that. Those pins could not have come from that motor the way it sits now. Someone probably did a top end on it at some point in the past and dropped them in there...

Hey Jeremy, I was referring to the fact that the oil pump shaft component turns freely in the mag and should be secure / locked on the fly wheel nut. Since it's the "upgraded" black version of the shaft it looks like the only way to check and verify if it'a broken is to pull the mag cover. So, I need to find a procedure on how to do this correctly so I don't damage the drive shaft. I guess you need to lift the engine to get at the bottom two bolts. I can feel those bolts, but I don't see how I'll have any room to break them free without lifting the dang engine.

This project gets deeper and deeper as I continue lol Craziness.

 

[mikidymac]

Just mark the outline of the bolt with a marker then put s 2x4 under the engine to hold it up. Assuming the rear engine mounts are good they’ll hold it in place. Just make sure if there’s shims under the front mount you put them back.

 

[mejim707]

Just mark the outline of the bolt with a marker then put s 2x4 under the engine to hold it up. Assuming the rear engine mounts are good they’ll hold it in place. Just make sure if there’s shims under the front mount you put them back.

So no need to remove the drive shaft or loosen the rear mounts? Only loosen the front mount and lift?

When you say mark the outline of the bolt, is this due to some clearance or calibration that was done for the drive shaft? I would have never thourght I needed to make any marks on a mount bolt. Whats the purpose of doing this?

Thanks again

 

[Sportster-2001-951C-Stock]

I wouldn't worry too much about having "air" in the fuel lines but you should pressure check them to make sure there are no leaks. This might not be air, it could be evaporated fuel. The fuel we have nowadays seems to evaporate easily, it's not uncommon to see bubbles.

If you don't believe me, siphon fuel from one 5gal tank to another using a long tube, you're liable to see bubbles, I know I do.

 

[mejim707]

I wouldn't worry too much about having "air" in the fuel lines but you should pressure check them to make sure there are no leaks. This might not be air, it could be evaporated fuel. The fuel we have nowadays seems to evaporate easily, it's not uncommon to see bubbles.

If you don't believe me, siphon fuel from one 5gal tank to another using a long tube, you're liable to see bubbles, I know I do.

Thanks for the reply Sportster! This thread went from air bubbles in the fuel lines to a broken oil pump shaft lol As of now I’ve rebuilt my carbs and now I need to remove the mag cover and replace the pump shaft.

Fun times...

 

[mejim707]

Just mark the outline of the bolt with a marker then put s 2x4 under the engine to hold it up. Assuming the rear engine mounts are good they’ll hold it in place. Just make sure if there’s shims under the front mount you put them back.

I don't mean to bother you about this, but do you have any recommendation on what shaft to use? It looks like the original shaft can be replaced pretty easily without the need to remove the Mag cover. But the updated version, the one I have, requires the Mag cover to be removed. Would you move back to the original, or stick with the new version?

Thanks