Another GTX Di

[G&J]

Hi 68ragtop

It's 30 degrees, feels like 32.5 with humidity, in Cairns at the moment living in the tropics I would love a nice snowy day and I am sure you would prefer our weather.

Anyhoo - put it all back together, cleaned and tightened as I went, and runs exactly the same as when I started, burbling, hunting idle.

Not sure what I should check next regarding the hunting, burbling, idle. Any other thoughts/suggestions?

Regarding low stator output: if it manages 13v (trickle charge?) at mid level revs I could probably live with it for running around the lake if I can sort out the missing, idle problem. Might have to pay the local dealer $120 to hook it up to the BUDS and run off a report to narrow down the fault?

 

[68ragtop]

The compressor can be checked by removing the air line out of the air rail & clamping on a chunk of hose with a gage dead ended to it. Hold the throttle to the bars so its in flood mode & see if it will pump up to 90 PSI while cranking & it should only take 3-5 seconds of cranking with a healthy battery & starter.

Do you have an air compressor & a regulator?
If so you can substitute the air in the rail with it. Might sound like witchcraft but it works & you can rule out your air compressor.

Remove the airline from the engine air compressor & leave the other end in the rail. Then using a cheater valve or regulator raise the compressed air pressure to a little above 80psi. as soon as it hits 78-80, you will (should) hear air escaping out of the rail through a tube that goes to the back of the hull. completely normal & you want that air circulating like that.

When you put your key on, the fuel pressure should go right to 107. Start the ski & see how it runs & what your pressures are. The DI's will run perfect on shop air. In fact, it will run smooth on the trailer with only 50lbs of air = only 77 lbs on the fuel gage. (sounds crazy, but I have done this) As long as the fuel pressure stays 27 lbs higher than the air pressure, Just can't be the other way around or it won't run much at all. The air compressor on the engine will be noisy while running as its not connected to anything. just an FYI.


But, going back to what you found earlier & you have 107 (mid point of the needle) when running & your gage is accurate, I suspect your engine air compressor is fine. As long as the pressure never drops, & only rises a few lbs when hitting the throttle.

You mentioned fuel pressure drops when its hunting. If you do the air compressor trick above, it should stay right at 107 at all times running, even if its hunting. the needle should be steady & unaffected.

One thing the candoo, or Buds can give you is the ability to pulse the air & fuel injectors, turn off each cylinder while running, etc. It definitely would help diagnose the problem.

I know these engines can test your will to let them live, I guess that's what drew me to them, the first one I got was a complete abomination & was a challenge to say the least. After many members on this forum helped me through it, I took it to the next level trying to understand them better. Once I understood, I really started to appreciate them.

Only reason I was focusing on the voltage was if you had a did in fact have a stator problem, & you had to pull the front mag anyway, you could check to see if the crank sensor or reluctor ring was compromised by corrosion.

I have an unorthodox way of testing if the air injectors work too. But its hard to explain...

 

[G&J]

Hi

I don't own a air compressor / regulator so can't test compressor that way, but on a positive note as you state should be OK as achieving 107 psi fuel pressure.

Regarding the hunting, reviewing the troubleshooting chart I am left with;

Bad sensor - need BUDS to narrow down?
Clogged injector - without BUDS need unit to swap?
Bad ignition coil - without BUDS need unit to swap?
Oil injection pump adjustment - no idea?

Am I missing anything?

 

[jhjesse]

Yeah what I was really meaning is your air pressure regulator. If I remember correctly it is down stream of your gauges. Correct me if I am wrong.

 

[G&J]

Yeah what I was really meaning is your air pressure regulator. If I remember correctly it is down stream of your gauges. Correct me if I am wrong.

Hi - I'm lost

Do you mean item 4 on the rail image below?

 

[jhjesse]

Yep that was what I was thinking

 

[G&J]

OK - I see it is not adjustable, do you think it might be fluctuating causing the hunting idle? Or low?

Might have to see if I can borrow an air compressor and regulator to test.

Edit: Might pop it out and have a look first......

 

[jhjesse]

Remember without a candoo I am only guessing, but with sooty plugs and throttle body it stands to reason the air is not being regulated properly. Again I am only guessing trying to help you find out what the problem is.

 

[G&J]

Thanks very much I appreciate the help!

 

[G&J]

Hi All - is there a trick to reinstalling the Fuel Injectors in the air/fuel rail assembly? I popped them out for a quick visual inspection and on refitting they don't quite sit right and the retaining plate screws don't line up?

The manual just says insert with hand do not use tool...

 

[68ragtop]

I'm guessing the o-rings are fighting you. might need to use some WD40, or light oil to get them to pop back in place.

Do you have it back together? Can you make a video of the fuel pressure gage from key on, to running?
Does your fuel gage hold pressure when you shut the ski off, or does it drop off quickly? The regulators really aren't much more than a calibrated valve & spring. the air side starts to open just under 80 lbs of air pressure & the excess air passes out #7 to the back of the hull. The higher the pressure & volume rises (from higher RPM's) to more it opens to try & maintain that 80's psi. The fuel side works the same way with a twist, it opens around 27 lbs & passes the fuel back in #8 to the tank. but as the air side rises from 0 PSI, that pressure is placed on the opposite side of the fuel regulator #3 causing it to rise 27 lbs above whatever the air pressure is. (thats what that little black tube near #3 is responsible for) Thats where the 107 comes from. But if it drops below that pressure from lack of fuel pressure that raises fits. IT has to have that 27 psi higher than the air or the fuel will not pass though the air rail correctly. But if the air is low, the fuel pressure will drop, but because the fuel is still 27 lbs above the air rail pressure it will still inject the correct ratio, so it should still run smooth on the trailer, but will not under load on water. Your issue seems like either there is something wrong with the ignition, air or fuel. Yes, I just listed everything an engine needs to run. IMO, If your compression is 140-145 like you said, reeds are good & fuel/air is healthy, either one of the sensors is giving inaccurate data (air temp, pressure, cps, etc) and the ecm is trying to compensate, or you have a bad coil, fuel/air injector. When using the candoo, one cylinder can be turned off. I believe its done by turning off the air & fuel injectors (maybe the spark) & the engine will still run surprisingly smooth & at the correct RPMs. I wonder if you pull one of spark plug wires it would do the same? I have never tried that. Sure wouldn't want to run it long as it will still be injecting fuel, but you could compare how each side runs solo to possibly narrow down if its coming from one cylinder or the other.

I have never tried this, so I do not know what it will do. I wish my toys where at home, I would try this to let you know. I have run them on one cylinder through the candoo & they run amazingly well on one cylinder.

jhjesse, is this something you could test? or are your skis in storage too? I'm thinking if it runs exactly the same on each side, its more likely a sensor, or maybe a wiring issue. If one side runs better than the other, might be easier to pin down.

Sadly, without a many of the tools mentioned in this thread, its not going to be easy to pin down your issue. Not impossible, just difficult with unconventional testing.

 

[jhjesse]

No my skis are not in storage, but I am in Midland Michigan for the next few weeks working.
I am thinking that the calibrated spring inside the air regulator has become weak. I am not sure that would show up on the candoo or not?? Is there some sort of manual test to check both the fuel and air regulators for proper functionality??

 

[G&J]

OK got it back together, bit of a DOH moment with the injectors I had them 180 degrees out... turn around and everything aligns and fits nicely. FYI: Swapping fuel injector position made no noticeable difference to how the unit runs, so I assume they are OK (or both faulty)?

It's a bit wet at the moment in Cairns as soon as the rain stops I will make a video.

Q: I see the only way to show a video is to link to youtube and the like, can't be uploaded to anywhere on here?

As background previous testing has shown;

Unit holds fuel pressure for long time with no apparent leakage.

Q: Is it possible the air pressure is fluctuating causing the hunting? I will see if I can source an air regulator as jhjesse has suggested (I see they are rather pricey... RRP over $260 might be cheaper to buy a whole rail... Would BUDS pick up dodgy air regulator?)

Iv'e got some second hand ignition coils coming I picked up cheap to do a little fault finding by replacement (agreed not best or ideal way to fault find) , they should arrive next week some time. But as burbling occurs on either/both cylinders unless both coils are on the way out this should not be the problem.

I have isolated individual cylinders by leaving plug in and placing HT lead on post. When running on either cylinder individually unit burbles and hunts same as when both are connected (only run for 10-20 seconds). Maybe the rear cylinder runs with a little less burbling (to use the technical term) but in no way would either be considered anything resembling smooth.

Q: Do you think I may have missed something with the fuel pump and/or filters? All I did was a visual inspection, I have not changed any filters. Would I be correct in saying that even though the fuel pressure looks OK if there was a slight blockage could this cause the hunting? Having said that with a little revs the engine does smooth out quite a bit and the fuel pressure gauge bounces around less as mentioned.

As you said earlier next step get out the DVM and check what sensor readings I can.

Q: Any suggestions regarding which sensors to check first? The troubleshooting chart does not specifically mention individual sensors.

 

[G&J]

Hi

This help?

[video=youtube;aVKgsCU1C0k]https://www.youtube.com/watch?v=aVKgsCU1C0k[/video]

 

[tkarvelis]

I was just thinking... If you pull your 12v battery out of a car or truck that has a larger CCA, and hook it up in parallel to the battery in the ski with jumper cables, it would provide a longer run time since the battery is larger. I would pull the regulator fuse or disconnect the regulator in case you have a something bad going on.

I know you are not supposed to charge the battery with the ski connected, but i do not think this will hurt anything.

 

[G&J]

A picture paints a thousand words they say.....

1. Clearer movie shot of fuel pump priming pressure [video=youtube;z-JXgiAVBYw]https://www.youtube.com/watch?v=z-JXgiAVBYw[/video] turned off sitting at 25 psi, priming goes to 27 psi.

2. Movie of how unit idles with front direct and fuel injector plugs disconnected, makes no difference to hunting idle... [video=youtube;IhLKSA1NdPQ]https://www.youtube.com/watch?v=IhLKSA1NdPQ[/video]

I have also done the same thing with other sensors such as throttle body, remove connectors temporarily, with no change to hunting idle. I think I need a candoo report/diagnosis to narrow down fault or dealer, is it BUDS, diagnosis?

 

[68ragtop]

If your gage is accurate, your pressure looks spot on at start up. I can't quite see the needle on the running video put it looks like its close to the mark? holding 25 psi shows the check valve in the fuel pump is good & a really healthy one can hold that pressure for many hours if not days. When you shut it off does it hold a higher pressure for a while. maybe 70-80 & slowly leak down? The check valve in the air pump will also that will keep the fuel pressure up even high for some time. In fact the higher it is, the quicker the restarts. The surging doesn't sound as bad as I was imagining, but sometimes the audio in these videos aren't as telling as in person. Have you removed the air line from the rail at all to inspect? Is it pretty clean & no signs of contamination?

Its starting to look like something that might require a candoo to see what the data is coming from the other sensors. Maybe something electrical. All of the mechanicals seem correct. The only other things that comes to mind would be if you have an air leak, but then I would suspect it to be ones side, not both.

But, I still wonder why your voltage is low. It should run smooth with under 13 Volts, its just not normal. All this work your doing makes me want to go get my RXDI so I can make some comparison videos for you.

Going back to the corroded electrical connector, what plug was that? Do you think any of the other wires look suspect, & if so what ones are they? Thanks for posting the pictures & videos, that helps get a feel for whats going on.

Any idea why the fuel pressure gage setup looks so complex with fittings? Was also curious what the device was that is inline to the left of it & if its permanently mounted?

When you remove the other sensor wires, does it trip the maint light? There are two TPS sensors on the throttle body of these skis & the are for redundancy as far as I can tell. But, unplugging one should trip the maint light. Not sure how long it has to run for that to happen though.

 

[68ragtop]

Also, keep in mind if you do go to the dealer, your ski is going to have a lot of faults stored. it will store the sensors & injectors having been unplugged, low voltage, etc. The way the ski stores & counts the fault codes is different than other skis. So if you do bring it in, make sure they understand how the codes are read in a DI. It seems a lot of dealers are loosing experience with these older skis & even though they have the tools to diagnose they are not all familiar with them. It's possible it could be something as simple as the pressure or knock sensor, but without reading the data it's providing, or having spare parts to swap out on hand, some of those type of problems are going to be hard to diagnose. Too bad we aren't neighbors instead of living on the opposite sides of the Globe. We could have a beer & try to figure it out.

 

[jhjesse]

Well the pressure regulator seems to be working. Wish I had an extra coupon on my candoo, I would ship it to you and see if we could figure this out.
Ragtop you think the tps is out of adjustment? Maybe check and see if the plastic cap on the tps adjustment screw is missing. If it is then can you set with an ohm meter?

 

[Sportster-2001-951C-Stock]

Correct me if I'm wrong but, are we saying one cylinder isn't firing at least intermittently? Or is that exactly what we're saying, we just don't know if the problem is a mechanical or electrical issue or maybe the MPEM is unhappy about something and causing this?

Maybe the injector is partially clogged?

 

[68ragtop]

He had unplugged the injectors from each side & it had the same stumble on either cylinder.
But, I not sure if he unplugged the air injector too & probably should have. I was not sure if it would run
this way but it appears too. when the candoo turns off a cylinder it turns both air & fuel injectors off & not sure about spark. The DI's run incredibly smooth on one cylinder, so my hope was that it would idle smooth on one cylinder & rough on the other. but it appears to be that same on both side. I have a bunch of things I am going to test for future reference on my rxdi when I get it home for the summer. just wish it was home right now & its too much trouble to get it. All; the summer stuff is in storage & the skis where the first thing to go in & they will be the last out. I suppose its possible the TPS's have been messed with or replaced & not reset. I don't think that will cause a rough idle, but maybe?

What's the history with this ski? previous owner give up on it, or do we know what might have been done to it? The gray coating on the ground bolt looks virgin so I am guessing its never been too far apart yet?

I would like to see the spark plug grounded & both air & fuel injectors unplugged & see how the idle is on each side/s Those being unplugged should trip the maint light tho, but might not effect the idle.

 

[Sportster-2001-951C-Stock]

Hmm, okay obviously I need to focus more closely, I was expecting one cylinder wasn't firing. Still, by disconnecting the injector that cylinder certainly won't fire. Disconnect them both and everything should stop.

It holds fuel pressure well, suggesting the injector isn't leaking. I guess the air injector is needed to push the fuel into the cylinder during the compression stroke.

There's a carbon dam in there somewhere that holds the fuel in place until the air injectors fires, right? Maybe those are damaged? Just shooting from the hip on this, I've never laid eyes on a 951 DI Maybe you have a point, if the air injector isn't firing then fuel won't go where it needs to be.

Incidentally, for FI outboards such as the FICHT or E-Tec we index the sparkplug (via selection and toque) in such a way to ensure the gap opening faces toward the injector.

Also I want to mention it's easy for one of the incorrect connectors to be swapped between sensors, the connectors are the same thus it's possible to get them on the incorrect sensor. Thus wire color code can lead to resolving this.

 

[68ragtop]

Sorry Sportster, I meant he unplugged them one side/cylinder at a time. Not both at once. Bad choice of words on my part. But seeing it will still inject air with the fuel unplugged I was hoping he could try unplugging both the air & fuel injectors at the same time, one cylinder at a time & see if its any different. I suppose your right, a spark is pretty meaningless at that point so that could stay plugged in.

The fuel sprays in just above the top of the air injector & the fuel & air are mixed right then as the air injector releases it into the cylinder. Its sure possible the air injector could be a problem, but I wouldn't think both of them would be bad at the same time. Really hoped in would miss on one side & not the other with things unplugged. If both side run the exact same isolated, makes me think its a different part of the system.

Whenever we get this deep into a problematic ski, It makes me want to work on it


I also don't think the wires are long enough on either air or fuel to mix up left to right? That would sure make it run like crap if it was even possible

 

[G&J]

Hi All

Can't fire the ski up to confirm, to early here, but from memory;

When unit is shut down fuel pressure immediately drops to 25 PSI and stays there.

Both cylinders idle / run rough when run individually, yes with both fuel and air injectors disconnected.

I disconnected the plug to the, I think it's called the air solenoid, and there was no change in how the unit ran. Meaning air pressure problem?

I'll answer the rest of the questions when I can fire up the beast.

thanks again everyone it's great having all you input and help

 

[68ragtop]

It should not drop back to 25 PSI right when you shut it off. If it does, I would suspect you might have an air leak. air injectors will normally leak a tiny bit, & so will the check valve in the air pump. But it should hold some pressure for minutes not seconds. If you can maybe you can make a few more videos later?

I would like to see a clear video of the pressure gage from start up, idling, a little rev & then shut off until the pressure drops back to 25 like you mentioned. Its normal for the air to leak down, but not within seconds of shutting it down.