99 SPX Voltage Issues?

[Strizzo]

when it starts, does it stumble to life, or fire off like you just pulled it out of storage and the gas finally made its way to the carb?

you did use OEM Mikuni diaphragms right? right?

edit: having to give it gas to start in the water usually points to being way rich, or needle/seats leaking, or non-mikuni diaphragms either holding the needle open or not moving like they should because they're too stiff.

 

[Minnetonka4me]

Duh...I think Strizzo is onto something. do a pop off test with the cover screwed on. I bet when you put the cover on its opening the needles and seats a little. I would think though it would run good on the high end.

 

[Strizzo]

yeah it should hold iirc 10psi for 5 minutes with the carbs all together.

 

[CReynoldsMIZ]

Nope they are all Mikuni in the carbs. So let me get this right, i need to set the carbs at stock and 3k rpm, if I turn the low speeds in and it revs up, then it is too rich at 1.5 (stock) turns out. If it revs up when turning down then the 1.5 turns was too lean. If I open up the LS to >1.5 turns then and it revs up then stock was too lean, and if it revs down then it means it is too rich? So basically I need to set it stock, 3k rpms, and turn it in or out until it the rpms reaches it's peak, then dips, and then move it back to the peak rpm?

I will check the pop off with the cover on tomorrow.

 

[mikidymac]

That is correct, but I think idle in the water is like 1400 rpm. I would check to make sure that the fuel inlet of the carb is holding pressure with everything together like the others had suggested before going any further. Remember to plug the return line. If you installed all new parts from the carb kits it is possible that the little arm that opens the needle can be a little bent and hold it open once the diaphragm is installed, if you look at the manual is shows that the arm should be flush with the internal casting.

I had a similar issue last year on a friends 1995 XP, rebuilt the carbs everything checked out pop off great held pressure then he took it out and was a pain to restart after sitting and almost did not make it back to the dock. He brought it back and when we pulled the flame arrestor and added some pressure to the fuel tank you could see one of the carbs dripping. Come to think of it does yours dribble? Anyways, when I took the carb apart there was a small fiber like the bristle of a tooth brush stuck in the needle that would not let it close. I have no clue where it came from or how it got there because I don't use anything like that in my garage and the carbs passed all tests but there it was.

 

[68ragtop]

As a hobbyist I haven't seen every scenario, but I do know I personally have a hard time distinguishing lean from rich sometimes with a 2-stroke. the symptoms can be similar. What happens if you leave the throttle closed, but pull the choke for restart?

For me, I tried so hard to figure out mine by doing these things & I never got a clear response from the ski.
If I was you, I would turn both low speeds out 3/4+ of a turn, see what happens to the idle, adjust that to 3K & retest in the water. If it seems to get better, its lean. unless water is a bit of a road trip, its an easy test.

I do like the idea of a pop off test with the diaphragm covers on, but, if your arms were bent that much to hit the covers, you probably would have noticed they were not very perpendicular to the metering block?

 

[mikidymac]

As a hobbyist I haven't seen every scenario, but I do know I personally have a hard time distinguishing lean from rich sometimes with a 2-stroke. the symptoms can be similar. What happens if you leave the throttle closed, but pull the choke for restart?

For me, I tried so hard to figure out mine by doing these things & I never got a clear response from the ski.
If I was you, I would turn both low speeds out 3/4+ of a turn, see what happens to the idle, adjust that to 3K & retest in the water. If it seems to get better, its lean. unless water is a bit of a road trip, its an easy test.

I do like the idea of a pop off test with the diaphragm covers on, but, if your arms were bent that much to hit the covers, you probably would have noticed they were not very perpendicular to the metering block?

It is not a pop off test with the covers, just 10 psi to make sure that the needle and seat will hold pressure from the tank.

 

[68ragtop]

It is not a pop off test with the covers, just 10 psi to make sure that the needle and seat will hold pressure from the tank.

Good idea!



Also, If I remember correctly, there is an adjustment screw on the accelerator pump lever too. At one point, I backed it way out so I would get no squirt for the first 1/4 opening of the throttle blades.

 

[68ragtop]

personally, If your ski was in my shop, I would let it warm up on the hose, then check the idle speed & maybe set it to 2000-2500rpm's (so you don't get lean run away) Then turn both LS screw in until you see the idle rise. if your at 1 turn out now, you might see it right away. at this point, its starting to go lean, & maybe too lean. Then I would back them out 1/4 turn at a time until the speed drops & stays dropped. somewhere just below the edge of the idle going up & 1/4 turn out is close to where you want to be with these carbs IMO. I had mine out 1/4 turn past where the idle speed dropped & it ran & restarted better than ever. it might have been a little rich but the 97's with the accelerator pump have really small ls jets.

 

[CReynoldsMIZ]

yeah it should hold iirc 10psi for 5 minutes with the carbs all together.

Okay. So how do you plug the return port? Just a vacuum cap? Will the 10psi blow it off?

Duh...I think Strizzo is onto something. do a pop off test with the cover screwed on. I bet when you put the cover on its opening the needles and seats a little. I would think though it would run good on the high end.

So am I doing a pop off test then as well? I wouldnt think that it would change at all since the pop off since the air is pushed through the bottom of the N/S but kinda confused here.

That is correct, but I think idle in the water is like 1400 rpm. I would check to make sure that the fuel inlet of the carb is holding pressure with everything together like the others had suggested before going any further. Remember to plug the return line. If you installed all new parts from the carb kits it is possible that the little arm that opens the needle can be a little bent and hold it open once the diaphragm is installed, if you look at the manual is shows that the arm should be flush with the internal casting.

I had a similar issue last year on a friends 1995 XP, rebuilt the carbs everything checked out pop off great held pressure then he took it out and was a pain to restart after sitting and almost did not make it back to the dock. He brought it back and when we pulled the flame arrestor and added some pressure to the fuel tank you could see one of the carbs dripping. Come to think of it does yours dribble? Anyways, when I took the carb apart there was a small fiber like the bristle of a tooth brush stuck in the needle that would not let it close. I have no clue where it came from or how it got there because I don't use anything like that in my garage and the carbs passed all tests but there it was.

Correct. I was talking about 3000 on the trailer, i am not sure what it is on the water, havent had the tto on the water yet. Okay so you guys are talking about bending the arm where the little red plastic piece hits on from the Diaphragm, correct? I am not sure if that is flush with the surrounding area or not, I didnt really check. I honestly never knew what that meant to have it flush but i understand the concept now and how if too high the red peice could touch it and cause flooding

As a hobbyist I haven't seen every scenario, but I do know I personally have a hard time distinguishing lean from rich sometimes with a 2-stroke. the symptoms can be similar. What happens if you leave the throttle closed, but pull the choke for restart?

For me, I tried so hard to figure out mine by doing these things & I never got a clear response from the ski.
If I was you, I would turn both low speeds out 3/4+ of a turn, see what happens to the idle, adjust that to 3K & retest in the water. If it seems to get better, its lean. unless water is a bit of a road trip, its an easy test.

I do like the idea of a pop off test with the diaphragm covers on, but, if your arms were bent that much to hit the covers, you probably would have noticed they were not very perpendicular to the metering block?

If I pull the choke for a restart, it really doesnt help at all, actually it hurts it, there is no way it would start with the choke closed. Usually I just hold the throttle wide open to get it started.

It is not a pop off test with the covers, just 10 psi to make sure that the needle and seat will hold pressure from the tank.

Gotcha

personally, If your ski was in my shop, I would let it warm up on the hose, then check the idle speed & maybe set it to 2000-2500rpm's (so you don't get lean run away) Then turn both LS screw in until you see the idle rise. if your at 1 turn out now, you might see it right away. at this point, its starting to go lean, & maybe too lean. Then I would back them out 1/4 turn at a time until the speed drops & stays dropped. somewhere just below the edge of the idle going up & 1/4 turn out is close to where you want to be with these carbs IMO. I had mine out 1/4 turn past where the idle speed dropped & it ran & restarted better than ever. it might have been a little rich but the 97's with the accelerator pump have really small ls jets.

I am at 1-1/2 turns out right now, which is the stock setting.

So tell me this, maybe I am just having a hard time understanding lean vs rich.

So I will start at stock settings, 1.5 turns out, 0 on the High, and 3000 rpms.

Im at 1.5 turns out now, if I turn the LS needle out and the RPM rises then the current stock setting is too _______ (rich or lean). If I turn it out and the RPM lowers, then it is currently too _______ (rich or lean?)

If I turn the LS needle in, and the RPM rises then I am too ______ (rich or lean?) If i turn the LS needle in and the RPM lowers then I am too ______(Rich or lean)

Lastly. Can I do any of this on the trailer with the hose and then "fine tune" it at the lake on the trailer.

While I am pulling the carbs tomorrow to check the PSI holding pressure, I will pull the RV cover and make sure all is time as well.

 

[68ragtop]

I wouldn't pull the carbs just yet. I like mikidymac's idea to pressurize the fuel line going to the carbs to see if the needles are leaking. No pop off needed as you already tested that. this is just to make sure the covers aren't interfering with the arms & holding the needles open when they should be closed.

As you back the screws out, it richens the mixture, so the idle should dome down if its currently a little lean. If its not lean, you will notice very little change at all. I know, it sounds backwards. Back the screws out 1/4 at a time, if you get out 2-1/2 turns with no change, bring them in to 2 turns out, then 1/4 turns at a time in until you see the RPMs rise. sometimes you need to wait 15+ seconds in-between turns to get a response in the engine speed. When it rises, back them out again 1/4 turn & see if it drops back down. If it does, your darn close to were it should be. The problem with a lean idle is, not only do you have a low amount of fuel, but you end up closing the butterflies to compensate for the higher (lean) idle. neither of those two things help the restart.

I'm not implying your lean, but its pretty easy to see where your at. But I would still drop the idle down to 2500 or less while you do this. when its all finished, do a final adjustment back to 3K

But who knows, after all this you might still find the valve is the wrong one, or mis timed?

 

[CReynoldsMIZ]

Wow I am on carb info overload. So this is where I am confused...

You say if im at stock, and I back the LS screw out and the the RPM drops, then that means that i am lean at stock? I guess I would think if the RPM rises when i turn the LS screw out, that means that the 1.5 turns out is too lean. Or are they both right? Im so confused. lol

 

[68ragtop]

Wow I am on carb info overload. So this is where I am confused...

You say if im at stock, and I back the LS screw out and the the RPM drops, then that means that i am lean at stock? I guess I would think if the RPM rises when i turn the LS screw out, that means that the 1.5 turns out is too lean. Or are they both right? Im so confused. lol

You have it correct. When the engine starts to go lean at idle, the RPM will rise. Less fuel = more RPM. too a point anyway. get too lean & it will stumble out & die. Being borderline lean is good for more horsepower & a crisp response, but this is just the idle circuit, so if its a little rich & it runs well, it will not effect your performance.

Sure don't mean to beat this to death on you. might not even be the culprit? Its just really easy to check without taking anything apart at all.

 

[Strizzo]

Okay. So how do you plug the return port? Just a vacuum cap? Will the 10psi blow it off?



So am I doing a pop off test then as well? I wouldnt think that it would change at all since the pop off since the air is pushed through the bottom of the N/S but kinda confused here.



Correct. I was talking about 3000 on the trailer, i am not sure what it is on the water, havent had the tto on the water yet. Okay so you guys are talking about bending the arm where the little red plastic piece hits on from the Diaphragm, correct? I am not sure if that is flush with the surrounding area or not, I didnt really check. I honestly never knew what that meant to have it flush but i understand the concept now and how if too high the red peice could touch it and cause flooding



If I pull the choke for a restart, it really doesnt help at all, actually it hurts it, there is no way it would start with the choke closed. Usually I just hold the throttle wide open to get it started.



Gotcha



I am at 1-1/2 turns out right now, which is the stock setting.

So tell me this, maybe I am just having a hard time understanding lean vs rich.

So I will start at stock settings, 1.5 turns out, 0 on the High, and 3000 rpms.

Im at 1.5 turns out now, if I turn the LS needle out and the RPM rises then the current stock setting is too _______ (rich or lean). If I turn it out and the RPM lowers, then it is currently too _______ (rich or lean?)

If I turn the LS needle in, and the RPM rises then I am too ______ (rich or lean?) If i turn the LS needle in and the RPM lowers then I am too ______(Rich or lean)

Lastly. Can I do any of this on the trailer with the hose and then "fine tune" it at the lake on the trailer.

While I am pulling the carbs tomorrow to check the PSI holding pressure, I will pull the RV cover and make sure all is time as well.

Just plug the return with your finger, or if you're afraid of a cap coming off, you can use a zip tie. You can do a pop off test but it isn't really relevant because the 38 or whatever psi isn't what opens the needle, it's the vacuum in the Venturi acting on the diaphragm, which is what you're adjusting with the low speed screw. With the screw you're adjusting the size of the opening between the carb throat and diaphragm to make the needle open more or less at idle. A pop off test with the carb assembled will maybe pop off crisp once, but then it'll probably leak off after that.

 

[CReynoldsMIZ]

it's the vacuum in the Venturi acting on the diaphragm, which is what you're adjusting with the low speed screw. With the screw you're adjusting the size of the opening between the carb throat and diaphragm to make the needle open more or less at idle.

This is just totally mind boggling to me.

So here's where we stand. I took it all apart, again.

I took the rotary valve cover off, broke out the ol timing wheel. Everything is absolutely perfectly timed, like not off a 1/2 degree or anything, it has the right rotary valve, the 159 degree. The rotary valve cover, while not original, is super clean, and doesnt look worn at all, it is in very good shape, and while I didnt measure it, I dont think there is a problem with the RV clearance. It all looked really tight.

I did have only one problem that could jump out at me. The rotary valve cover gasket/o ring was SUPERRRR streched, like i could pull the slack down about 2 inches. I read somewhere online, where you could boil a rubber o ring and it would shrink, maybe it boils out the oils and shit or, hell I dont know. But anyways, it worked, I didnt have time to wait for a new one so thats why I tried it. Anyways, it tightened back up and felt really pliable and like new so I put it back on and tightened it all up and reinstalled the carbs again.

Didnt really make too much difference, it seems to start and idle a little bit easier, but at the same time, it still doesnt seem perfect. But it does seem easier to restart, and all in all a little better. But im still perplexed. I checked the O ring on the water seperator, that all looked good. Made sure all the clamps on the fuel lines are tight, they are.

Even switched out the CDI to make sure that couldnt be a problem. It wasnt. Idled exactly the same with both CDI's. The only thing I can think of anymore, is an air leak somewhere, or still another carb problem. It still feels like leaky needle/seat when restarting, but there is no way that can be it.

Im at a loss. Im still at stock 1.5 turns out on the LS, whenever I tried adjusting that on the trailer it seemed like it ran worse whenever I moved it in or out.

 

[Strizzo]

So did you test the needle holding pressure with the carbs assembled?

 

[CReynoldsMIZ]

I did, I'm going to do it better tonight tho. Do I need to plug the supply line on the mag carb. It went down slowly, didn't hold super well, prob went down 1 psi every 30 sec.


So update. Took it to the lake today, turned up the idle, and it ran better, still wanted to die at idle. So I shut it off after about a 10 min run, and it would not retart at all. Nothing. Almost started a couple times, but wouldn't. Took it out of the water and it fired right up, but put it back in the water and died within 10 seconds. I noticed after I got towed to the let trailer that one on the fuel lines connected to the filter was tightened too much and leaking. Didn't take it back out. Shamefully rode the old Yamaha all day with absolutely no problems....maybe it is a sign.

Ugh, anyone think a small fuel leak could cause this? I'm doubting it at this point but idk. I'm going to rip it apart down to be RV and measure the clearance tonight and rule everything out.

I'm starting to think...gulp. Engine.

 

[Strizzo]

I did, I'm going to do it better tonight tho. Do I need to plug the supply line on the mag carb. It went down slowly, didn't hold super well, prob went down 1 psi every 30 sec.


So update. Took it to the lake today, turned up the idle, and it ran better, still wanted to die at idle. So I shut it off after about a 10 min run, and it would not retart at all. Nothing. Almost started a couple times, but wouldn't. Took it out of the water and it fired right up, but put it back in the water and died within 10 seconds. I noticed after I got towed to the let trailer that one on the fuel lines connected to the filter was tightened too much and leaking. Didn't take it back out. Shamefully rode the old Yamaha all day with absolutely no problems....maybe it is a sign.

Ugh, anyone think a small fuel leak could cause this? I'm doubting it at this point but idk. I'm going to rip it apart down to be RV and measure the clearance tonight and rule everything out.

I'm starting to think...gulp. Engine.

There's your problem! With the return plugged (both on the mag side) the needle needs to hold 10psi for 30 seconds. If it is dropping at all, the diaphragm is putting pressure on the lever and allowing it to leak, or the o-ring around the seat is leaking.

 

[CReynoldsMIZ]

Think I found the problem. I just got home and lookin at it in the garage. Was going to change the 5/16 supply line which is leaking as well. The freaking fuel selector is leaking like a mofo. I am running a 1/4" fuel selector on 5/16" lines. I'm pretty sure this leak is doing terrible things to my fuel system. Anyone else with me on this?

I really don't think it is in the carbs. Should I just get a new 5/16" selector? Or should I get some 1/4 fuel lines and get a 1/4" to 5/16" barb and do it that way? Does anyone think the 1/4" fuel line barbs will restrict fuel flow?

 

[KayakNFly]

I don't think the 1/4 inch lines/barbs would make a difference as all the older 787 engines used 1/4 inch lines and barbs throughout. Only real difference is the accelerator pump between 96 787 and 99 787 fuel system.

 

[CReynoldsMIZ]

God I can't for the life of me find the 5/16" fuel selector I took off of the ski. Hey [MENTION=41828]Minnetonka4me[/MENTION]. Got any real clean 5/16" fuel selectors or any new ones? Also, there was a fuel filter on the ski, it is 1/4" plastic barb as well. Pull the supply line off because it was leaking right there at the filter, and since the line is 5/16" and the barbs are 1/4" whoever put it on tightened it so tight so it wouldn't leak that it almost pinched the fuel barb closed. Between that leaking fuel filter, the pinched barb on the fuel filter, and the leaking fuel selector, I hope the problem can be cured with this easy remedys. I already replaced the supply line to the carbs to the water separator, removed the fram fuel filter, and now trying to figure out what to do with the selector.

Anyone know where to find a 1/4" to 5/16" barb reducer so I can reinstall my selector? Lowes doesn't have anything

 

[Minnetonka4me]

Ive got good used 5/16 fuel selectors and water separators...PM me if you want to get some on the way tomorrow.

 

[Strizzo]

I don't think the 1/4 inch lines/barbs would make a difference as all the older 787 engines used 1/4 inch lines and barbs throughout. Only real difference is the accelerator pump between 96 787 and 99 787 fuel system.

97 and later 787s use a mix of 5/16 and 1/4 fuel line. Kinda silly considering there's a reducer between the water separator and the carbs.

 

[CReynoldsMIZ]

If I could just find a reducer I would be set because it is a brand new selector. Anyone know where to find some? Tonka I would need the selector in my hands by Wednesday evening. Would that be a problem? If rather just by reducers but idk if I can find any

 

[racerxxx]

Just go drop $25 on 1/4" fuel line and use your new selector. Zero waiting involved.

Sent from my SGH-T889 using Tapatalk