Another GTX Di

[68ragtop]

Between each winding you should see .1 to .5 ohms, but closer to .1 between each leg would be correct. .5 seems a little high even though its barely in "spec" 1 ohm is for sure high.

If you unplug the R/R, start the ski & measure the voltage across each leg it should be 35vac to 70vac from 1450-3500 rpms. If the engine is still hunting with the battery charged & the RR unplugged I doubt the voltage is causing your engine problems. while this will trigger the Maint warning having it unplugged, the idle should be smooth. low voltage is a problem, but unfortunately not the one thats causing the other issues. Sure sounds like one leg is not producing voltage tho.

One thing to consider is an ohm meter can read good resistance & voltage across a bad connection when there is no load, but as soon as the load is put on those wires the connection fails. The corrosion you mention has me thinking it might be something like that. The GTX has two stator connections, I think? One near the mag case & one at the R/R ? Another possibility is the mag case has been compromised with water & there are problems in there. But, I would be more suspect of all the connectors outside of the engine between the three yellow wires coming out of the case, to the R/R. especially after your corrosion findings. Are you taking the plugs apart, or how are you cleaning them? Really need to nail down that voltage problem.

On the engine side of your problems, I wonder if its possible that some of the other connections have been compromised? Could be getting fluctuating readings from the manifold intake pressure sensor, or maybe from the TPS's? exhaust temp, air intake temp, etc.

Also, it's worth checking the reed valves. On a GTX, I think there is enough room to drop the throttle body down without disconnecting everything & look into the boots with a mirror? The exhaust pipe will probably make this difficult to do, but worth looking at. removing them to inspect would be best, but you can at least see if all 8 pedals are intact with a mirror, of maybe a camera? The MAP sensor is in the front boot where your lower compression cylinder is. It only reads the pressure on the mag side & assumes all is the same on the PTO side. either side could give you problems, but the Mag side I would expect would give the biggest fits because thats the side thats being measured.

I know this can be a long road diagnosing these DI's but if you check everything thoroughly & make no assumptions, it can be figured out. Just don't skip a test because it seems like its not relevant. They are all important.

 

[G&J]

Hi - I'll be away for a few days, will report / update next week. Thanks again

 

[68ragtop]

Sportster, What is a rectified, but unregulated charging system capable of for voltage? If he lost one leg, or diode set in the R/R wouldn't that equate to around 12V volts or so? Thought it was 18+ volts at higher RPM's? Seems like he's not getting all corners of the stator?

 

[tkarvelis]

On my DI that had a bad stator, I was getting 12 or so volts. Mine however, showed an open on one leg of the stator to another leg.

 

[G&J]

If you unplug the R/R, start the ski & measure the voltage across each leg it should be 35vac to 70vac from 1450-3500 rpms. If the engine is still hunting with the battery charged & the RR unplugged I doubt the voltage is causing your engine problems. while this will trigger the Maint warning having it unplugged, the idle should be smooth. low voltage is a problem, but unfortunately not the one thats causing the other issues. Sure sounds like one leg is not producing voltage tho.

Hi

After a great deal of mucking around I managed to measure the stator output, all are around 40v AC with reg/rec disconnected. Note; No change to idle it was NOT smooth, still hunting - more on that in a moment. As a matter of interest my difficulty was getting a decent electrical connection with the DVM leads as I do not have the breakout cable. Also I noticed when measuring the voltage that the connector to the housing cover seems a little loose - can move in and out about 1/4 inch. Checked resistance of all wires/connectors all OK.

Regarding cleaning connector pins I am using - DeoxIT Contact Cleaner & Rejuvenator - Solution Kit. I am not breaking down the connectors just cleaning the pins at this stage.

Remeasured voltage across battery, no change starts about 12.5 and if I rev the unit the voltage slowly increases to about 13v.

With the idle still hunting and at a loss as to the cause I thought I would try a little logical fault finding to try and isolate the problem. Previously swapped ignition coils and checked cabling, no fault found resistances measured OK, connectors cleaned. Re-seated and tightened all positive air pressure hoses, a couple little loose but no change to idle. Next disconnected front electrical connector to air/fuel rail no change to start or idle!!! Disconnected rear electrical connector unit wont start or idle....

Putting aside charging system fault for a moment.....

So it looks like idle problem is front air/fuel injector system? I see in the manual not to play with the direct injectors as they require special tools to install. Can I service the air/fuel rail itself? Or the fuel pressure regulators to narrow down the fault? Or am I going round in circles?

Haven't reached the end of my tether yet... Also have not checked reed valves or other suggested sensors... yet.....

 

[68ragtop]

You might need to check the voltages of the stator with a load on them. Did the the voltages rise closer to 70vac when you revved it up close to 3500? still possible that they check fine with no load, but you have one failing when there is a load. Is the 13vdc at idle? If you but a small amperage battery charger on the battery (with it disconnected) will that voltage eventually rise to 13.5 or so? Did your 1 ohm reading go away, or are they all closer to .1 now?

I would look at the reeds. They might be just fine, but not that hard to drop the throttle body down & have a look you don't have to take the cables off, just the air box, support bracket & clamps IIRC. you can try to look inside with a light & mirror, or maybe a camera. Or better yet see if you can remove them. Yes, time consuming but doesn't cast anything & throwing new parts on when nothing is figured out is witchcraft on a DI

Injectors are supposed to be replaced in pairs I believe because of wear & hours. you don't want one that flows more or less than the other.

you can test the injectors output with a pulse timer. There are no specs on the amount they should flow, but you can measure how much each one and compare them to see if they are the same. if they are plugged up, they will more than likely be different.

 

[Sportster-2001-951C-Stock]

I think you can check stator resistance and associated cabling to the stator itself from the regulator connector, this should help isolate everything feeding up to the regulator.

G&J - Touch your ohmmeter leads together with setting at lowest resistance and note reading, this must be subtracted from the reading when measuring stator resistance for accuracy. Maybe your ohmmeter leads have some resistance?

All three phases are reading the same, that's encouraging. Maximum of 13 volts isn't encouraging but if the battery hasn't recovered from cranking over it might take some time for voltage to stabilize. My carbed seadoo regulates at 13.8 volts, which is just high enough to maintain a lead-acid battery charge. Anything lower once stabilized is undercharging as far as the battery is concerned.

ragtop68, doesn't 1 Ohm stator seem high to you, I usually measure 0.1 Ohms on most stators.

Good to hear you've isolated a cylinder injector, this is encouraging.

Good day mate and good hunting!

 

[G&J]

You might need to check the voltages of the stator with a load on them. Did the the voltages rise closer to 70vac when you revved it up close to 3500? still possible that they check fine with no load, but you have one failing when there is a load. Is the 13vdc at idle? If you but a small amperage battery charger on the battery (with it disconnected) will that voltage eventually rise to 13.5 or so? Did your 1 ohm reading go away, or are they all closer to .1 now?.

Hi 68ragtop

No voltages does NOT rise as revs increase...

And 13vdc is at revs and it takes a little while to get there, reg/rec working hard...

I will recheck resistance but don't hold much hope, stator resistance high, voltage low = new stator. Does the engine have to be removed to replace the stator? I'm wondering if I have the tools and the inclination to remove the engine, replace the stator, replace the injectors and whatever else I find along the way. Maybe time to cut my losses, sell for parts?

On another note can I swap the injectors to see if the fault moves from front to rear cylinder?

 

[G&J]

I think you can check stator resistance and associated cabling to the stator itself from the regulator connector, this should help isolate everything feeding up to the regulator.

G&J - Touch your ohmmeter leads together with setting at lowest resistance and note reading, this must be subtracted from the reading when measuring stator resistance for accuracy. Maybe your ohmmeter leads have some resistance?

Hi Sportster

I have checked cabling and connectors from regulator to stator, all ok.

Regarding ohmmeter yep subtracted lead resistance to get stated readings, all high one more than the other two windings = dodgy stator. Item 3 to replace, replaced reg/rec and battery.

Is there anything I can do with the rail and injectors before replacing such as soaking or the like to remove any residue? I'm probably clutching at straws a bit here, Item 4 to replace...

 

[68ragtop]

I have tested DI injectors. Not to see how much they flow as I do not have that spec, it was to compare them.

But, its not a simple test. You need to remove the rail with the fuel injectors still installed, (air injectors removed). supply an outside 12V source to the fuel pump so it runs continuous during the test.
hold a graduated measuring tube under each injector & cycle them using a pulse tool. Run them the same amount of cycles & see if they produce the same amount of fuel IF you have a problem, they will more than likely Not have the same output volume.

But, I would still take a peek at the reeds before going after the injectors. No doubt your surging is air/fuel related, but more than likely its the ECU doing it from other readings that are not in spec. Just my thoughts.

Don't start throwing parts at it just to rule things out. that will get expensive & frustrating.

Also, on the voltage I was talking about the A/C voltage, not DC. you should get near 70VAC at 3500 RPMS.
Would be nice if there was a way to measure that voltage while the R/R is plugged in & battery hooked up. Then there would be a load on the wires. But, you would have to tap into the wires to do so.

 

[68ragtop]

ragtop68, doesn't 1 Ohm stator seem high to you, I usually measure 0.1 Ohms on most stators.

I have not tested that all that many of them, But I found them closer to .1 ohm also.
I think spec is .1 to .5 but the ones I tested where not that high

 

[G&J]

Also, on the voltage I was talking about the A/C voltage, not DC. you should get near 70VAC at 3500 RPMS.
Would be nice if there was a way to measure that voltage while the R/R is plugged in & battery hooked up. Then there would be a load on the wires. But, you would have to tap into the wires to do so.

Hi 68ragtop

I am only getting 40VAC at about 3500 rpm.

I will have a look at the reeds today, and I haven't ordered any more parts yet lol

 

[68ragtop]

So your getting 40vac between each of the three yellow wires unplugged & at 3500 RPM's?

What do you have at idle?

 

[G&J]

Yes.

At idle voltage fluctuates, with hunting, at about 20 VAC. Far too low.

 

[68ragtop]

Im going to look up the specs, I don't want to be steering you wrong, but it does sound low. With the crazy idle you have, thats probably not helping getting an accurate idle voltage tho.

EDIT:

have you dropped the throttle body yet on this ski? Its really easy to do.

 

[G&J]

No haven't dropped the throttle body yet... might try shortly. Any tips?

Edit: Can I remove the exhaust to make access easier?

 

[68ragtop]

Pretty easy, Remove the two nuts/bolts & remove the air horns.
Then look where the air box connects to the top of the throttle body & remove the clip that holds them together.
Tip the box towards the hull & you should be able to lift it up & out towards the back of the ski.

Then loosen the two band clamps (one on each boot) in front off the throttle bodies, then remove the last bolt that supports them from the exhaust pipe. & they should pull out & lay down out of the way. With the exhaust pipe in place you won't be able to see in there, but should be able to possible take some picts with a camera, or use a mirror & a flashlight.

The Mag side band clamp is much easier with a long extension.

I will see if I have some pictures with those things. Pretty sure I do & I'll post them.

 

[68ragtop]

this might help.

 

[68ragtop]

Also, did you say the connector going into the mag case was loose? I wonder if the mag case was filled with water at some point? Maybe the mag is corroded beyond recognition? That might mess with the output voltage & the crank position sensor. I'd still look at the reeds first though. Pretty easy, once you've done it. The exhaust is not convenient, but you can get around it in a GTX.

 

[G&J]

HI

OK dropped the throttle body, as you say pretty easy once you get into it. They look ok to me, bit of carbon but I would say expected running on trailer as sportster previously pointed out. Images attached.

Yes stator mag case connector is loose, it can be pushed in and out about 1/4 inch. That can't be accessed/checked though without removing the engine can it?

 

[68ragtop]

before you put the throttle bodies back on, can you see all 8 pedals though each hole? just make sure to look thoroughly everywhere you look. For it to run as you described I would expect to see broken pedals, & its not looking like that so far.

I'm thinking you can remove the mag cover to inspect things. Another easy thing to remove, but I am trying to thing if the exhaust is in the way. IT might be....... Hmmmm.

thanks for the picts, that is very helpful getting everyone on the same page

Depending on how your phone/camera focuses, you might be able to put it right against the boots? that temp sensor on the PTO side can be pulled out of the boot if its blocking your view.

 

[68ragtop]

Found a picture from my last install. Looks like you would have to support the engine as the front mount is part of the cover. Oil pump should be removed so its easier to re-install & the case cooling lines would have to be removed. All easy stuff, but might not be easy to access with the head pipe in place. Head pipe is easier to remove with the throttle bodies down, but I believe a 2001 uses a gasket on the manifold to head pipe so that will have to be replaced if you pull it. Second half of the pipe could stay in place though. Just remove the band clamp.

But, things could be ok under there too. Its a crapshoot & a bit more work. I wish I had my RXDI at home I could check those voltages in real time for you to see if it warrants tearing it apart. All my summer days are still in storage. In fact its actually snowing here in GB Wisconsin right now

 

[jhjesse]

If the reeds look good and you have black soot, I would start looking at compressor pressure at the air regulator. Maybe not enough air and too much fuel. Just a thought.

 

[G&J]

I took some more photos and all pedals look OK.

 

[G&J]

Thanks jhjesse

Other than the fuel pressure gauge air compression adapter is there a simpler way to test the compressor?