Another GTX Di

[Sportster-2001-951C-Stock]

Oh no hassle man, we all enjoy helping and satisfaction knowing you'll have a good time using your ski afterward.

It's possible the regulator circuit is working correctly and the problem is somewhere else so we need to measure the DC current from the regulator to confirm. If something is loading the circuit beyond 15A the voltage will be low and I suspect maybe the fuel pump may be doing that.

If the rectifier isn't producing DC current well then we need to consider why (stator perhaps).

Cheers, mate!

 

[tkarvelis]

I purchased one of these bad boys at a local Harbor Freight store here in the states. This will allow measuring up to 30 amps, and plugs into the fuse socket. I wanted to know what my current draw was for my fuel pump. It should be able to measure the current of the rectifier also.

 

[Sportster-2001-951C-Stock]

Nice, that should work perfectly for this. Just remove the REG fuse and plug this in then fire up for the moment of truth.

So tkarvelis, tell us what you measured for the fuel pump current?

 

[Sportster-2001-951C-Stock]

BTW, probably nobody is interested but you can make your own shunt resistor from a piece of copper wire and measure the voltage drop across the shunt to determine the DC or AC current (depending on the preference, in our case DC).

For instance, at 20 Amps if we build a 0.01 Ohm resistor the voltage drop will be 0.200 volts, or 200mv.

A piece of solid copper wire 26 AWG (15.9 mils diameter) with length of 2.925" will have a resistance of 0.01 Ohms...

So, a current of 10 Amps DC across this length of wire will have a voltage drop of 0.100 volts DC, or 100mvDC

So you just need 3" of solid copper 25AWG wire (0.0159" diameter), lol.... Cheap enough, eh? Pretty thin wire though. A thicker shunt of the same length will drop less voltage, we can go there if you want, lol!

 

[tkarvelis]

Nice, that should work perfectly for this. Just remove the REG fuse and plug this in then fire up for the moment of truth.

So tkarvelis, tell us what you measured for the fuel pump current?

Well, mine was an aftermarket pump, and it was around 6 amps. I don't know where the pump came from, but I know it was aftermarket.

 

[tkarvelis]

Sure... What size for 40 amps. I want to build a 12v power supply for my ham gear... LOL

I noticed you can only run the testerfor 10 seconds at 30 amp... I guess they did not use large gauge wire...

 

[Sportster-2001-951C-Stock]

Well, mine was an aftermarket pump, and it was around 6 amps. I don't know where the pump came from, but I know it was aftermarket.

Good to know thanks. Hopefully your regulator puts out more than that at low speed. I don't recall what others have measured but I'm sure it's posted somewhere. Sounds close though, can't recall exactly.

 

[Sportster-2001-951C-Stock]

Sure... What size for 40 amps. I want to build a 12v power supply for my ham gear... LOL

I noticed you can only run the testerfor 10 seconds at 30 amp... I guess they did not use large gauge wire...

I saw where there are a few similar types on ebay, a couple have blade fuse slots in the side of the probe in case the circuit is shorted. Stupid me (brain in neutral), I connected my ammeter across a battery last week and soon as I saw the spark knew I had my probe connected to the current test banana jack.... Yep the side of the meter got hot real quick! Inside, I could see the wire had heated up. Woops!

Here's a table I found of copper wire resistance, maybe I need Tungsten wire, lol?

Copper wire resistance table

AWG Feet/Ohm Ohms/100ft Ampacity* mm^2 Meters/Ohm Ohms/100M

10 490.2 .204 30 2.588 149.5 .669
12 308.7 .324 20 2.053 94.1 1.06
14 193.8 .516 15 1.628 59.1 1.69
16 122.3 .818 10 1.291 37.3 2.68
18 76.8 1.30 5 1.024 23.4 4.27
20 48.1 2.08 3.3 0.812 14.7 6.82
22 30.3 3.30 2.1 0.644 9.24 10.8
24 19.1 5.24 1.3 0.511 5.82 17.2
26 12.0 8.32 0.8 0.405 3.66 27.3
28 7.55 13.2 0.5 0.321 2.30 43.4


AWG dia circ open cable ft/lb ohms/
mils mils air A Amp bare 1000'

10 101.9 10380 55 33 31.82 1.018
12 80.8 6530 41 23 50.59 1.619
14 64.1 4107 32 17 80.44 2.575

Shunt resistor of 0.01 Ohm:

14 AWG 0.516/100 is .00516 Ohm/ft

0.01 Ohm / 0.00516 Ohm/ft = 1.94ft

 

[Sportster-2001-951C-Stock]

There's nichrome wire on ebay, saw one at 4.1 Ohm/ft so an inch maybe with some good steel clamps?

 

[G&J]

Thanks tkarvelis I found a similar unit from a mob in Australia called Repco, ordered one should be here in a couple of days.

 

[G&J]

Thanks guy's - Soon as I receive circuit tester I'll test the current draw. I will check the the FP 15A, reg/rec 25A and battery 25A current and report back.

 

[Sportster-2001-951C-Stock]

Cool G&J, hopefully I don't miss your update but will be "listening". Have a good one, friend!

 

[G&J]

Hi All

Received the DC current tester (same a tkarvelis) very quickly tested current draw (will have to do again as was rushed this time - next time with slight throttle to maintain constant revs as when running at idle GTX Di unit revs up and down cyclically ... )

1. Fuel pump fuse - at turn on priming pump draws 4.5A. When idling draws from 7ish to 9ish amps, fluctuating with revs.

2. Regulator and Battery fuses - 7ish to 10ish amps again fluctuating with idle

Thoughts?

 

[tkarvelis]

Did you ever get this resolved? I have been thinking about your readings, and I am not too surprised on the two current readings above. Measure the current through the BATT fuse. My gut is telling me that you will read 0 amps through it. There is also a 30 amp fuse in the rear electrical box that you should check also.

 

[Sportster-2001-951C-Stock]

Hi All

2. Regulator and Battery fuses - 7ish to 10ish amps again fluctuating with idle

Thoughts?

REG - If this fuse current is 7~10 amps then it seems it's charging the battery. Is battery voltage reaching over 12.5V as well?

Sorry, I forgot the original problem.... and didn't see your update.

Low battery voltage? How about after riding, is the battery voltage maintained during riding or does it fall under 12.5 Volts?

 

[G&J]

Hi

I haven't had a chance to get back to my circular fault finding journey recently... been moving house...

My fault(s) or rather the SeaDoo's are;

1. What I would consider a little rough and wandering idle - plugs changed, fuel pressure OK
2. Measurable voltage at battery does not go above 12.5 v at idle, revving, whenever. Replaced rectifier/regulator - nil difference - measured resistance and voltage here there everywhere all appears to be OK - did have some dirty pins on ECU (or whatever the correct name is)
3. As soon as I rev a bit I get the red warning/error light
4. At rev unit starts to 'burble' or is in limp mode?

I will, as soon as I get a chance, re-conduct the current draw tests to try and narrow down the fault. I am a little confused by what appear to be correct or OK current measurements but no change in voltage? Something sucking too much current? Is the fluctuation mentioned above normal?

Next I will have to have a look at the Yamaha - let the 19 year old borrow it and it's come back with a tow rope tangled around the drive shaft... sigh...

 

[Coastiejoe]

The other half of the charging system is the stator which is behind the flywheel. It is testable using a DVOM and measuring resistance. Have you done this test and know what the correct values are?

You say fuel pressure is good. Did you use a gauge or are you basing it some other way? At idle it should be 117 PSI for example.

 

[G&J]

Hi

Yep tested stator voltage and resistance - OK.

Unit has in line fuel pressure gauge and yep again 117 PSI. I am however seeing the idle Rev up and down a little meaning a fluctuating fuel pressure at the guage, this steadies at revs. So far everything I check is in specifications..... hence my confusion...

 

[Sportster-2001-951C-Stock]

Hi

I haven't had a chance to get back to my circular fault finding journey recently... been moving house...

My fault(s) or rather the SeaDoo's are;

1. What I would consider a little rough and wandering idle - plugs changed, fuel pressure OK
2. Measurable voltage at battery does not go above 12.5 v at idle, revving, whenever. Replaced rectifier/regulator - nil difference - measured resistance and voltage here there everywhere all appears to be OK - did have some dirty pins on ECU (or whatever the correct name is)
3. As soon as I rev a bit I get the red warning/error light
4. At rev unit starts to 'burble' or is in limp mode?

I will, as soon as I get a chance, re-conduct the current draw tests to try and narrow down the fault. I am a little confused by what appear to be correct or OK current measurements but no change in voltage? Something sucking too much current? Is the fluctuation mentioned above normal?

Next I will have to have a look at the Yamaha - let the 19 year old borrow it and it's come back with a tow rope tangled around the drive shaft... sigh...

Okay, I know how fun moving is, done that too many times I learned my lesson finally!

If you remove the REG fuse, this is disconnecting the regulator output. The voltage should be lower while the fuse is out due to no charging.

I don't know if you've tried the ski in the water but this is the best way to know how badly or good they run, it's difficult to know if it's not running correctly while on the trailer.

As far as the red light goes, this is low battery "12V LOW" light, correct?

Remember, after starting the engine the battery voltage will be low due to cranking the engine. It may require several minutes of running until the battery receives enough charge to bring the voltage back to normal level. If this is happening, it's normal. A run in the water should help answer this question and many more.

What I'm saying is, I'm not convinced running on the trailer is a reasonable diagnostic test at this point, it's hard to know if it's running correctly on the trailer b/c there's no load on the engine.

If you still think it's not right then we'll take it from there but 7~10A through the REG fuse says it's at least providing some charging current and fuel pump current is less than this so we can say it's not fuel pump loading down the voltage.

As you rev the engine, fuel pump current drops, correct? I think this is normal. Then REG fuse current drops by the same amount, right? This seems normal. But it will take some time for the battery voltage to recover from crank starting the engine even if the charging circuit is working normally so be patient, I'd put it in the water again.

Cheers, let us know how it goes.

 

[Sportster-2001-951C-Stock]

Hi

Yep tested stator voltage and resistance - OK.

Unit has in line fuel pressure gauge and yep again 117 PSI. I am however seeing the idle Rev up and down a little meaning a fluctuating fuel pressure at the guage, this steadies at revs. So far everything I check is in specifications..... hence my confusion...

Yes, everything seems normal. But.... Running on trailer will not be a good way to judge if there's still a problem, running in water is the only way to know a problem still exists b/c it's difficult to judge on the trailer.

You can back the trailer into the water to submerge the jet pump and run for 5~10 minutes to get a good feeling if the engine isn't running properly.

 

[G&J]

Hi All

Went out for a couple of quick test runs...

Test run 1: Old regulator/rectifier fitted, brand new battery. Unit starts OK idles a little rough and almost immediately red light starts flashing and MAINT appears on dash. Rev a little, continues to run rough sounds like it is missing? and warning light and MAINT still on. Fuel pressure hovering around 117 PSI smooths out when rev higher, voltage across battery idle rev whatever no more than about 12.3 V, at end of run battery voltage low about 11.9 V.

Test run 2: The missing reminded me of a fault I experienced years ago on another beast that had an ignition coil fault, specifically broke down / no spark randomly. Fitted new rectifier/regulator and charged battery overnight. As I don't have replacement ignition coil to test swapped ignition coils positions and checked & cleaned all connections, again one connection had corrosion and needed cleaning, this seems to be a very common occurrence on this machine. Took unit for another run on the water - starts good, idle seems smoother and seems to rev a little more smoothly before misfiring started again.... Fuel pressure OK at 117 PSI and voltage across battery, at rev, at about 12.8 volts slowly climbing towards 13 volts whilst slightly revving. At end of run battery voltage good at 12.4 volts. Oh and no warning light or MAINT at idle or initially, both did appear eventually at higher rev after misfiring for some time.

Q: How do you tell the difference between what I am calling misfiring and limp mode?

Think I will replace ignition coil/s next. Does this sound like the right/best move next?

 

[Sportster-2001-951C-Stock]

Does fuel pressure remain over 100psi at all times while running? Are both spark plugs the same color or is one lighter? I've found often when a coil is failing it seems to work well until it reaches normal operating temperature then begins breaking down. A light spray mist from a water bottle while running can often cause a flaky one to reveal itself, same for plug wires.

Let's see if we can get [MENTION=57696]68ragtop[/MENTION] to join your thread, he's "Mr. DI" to you and me.

 

[G&J]

Does fuel pressure remain over 100psi at all times while running? Are both spark plugs the same color or is one lighter? I've found often when a coil is failing it seems to work well until it reaches normal operating temperature then begins breaking down. A light spray mist from a water bottle while running can often cause a flaky one to reveal itself, same for plug wires.

Let's see if we can get [MENTION=57696]68ragtop[/MENTION] to join your thread, he's "Mr. DI" to you and me.

Hi


Image of plugs attached look the same to me, it was previously stated "foul pretty quickly when running on trailer and short run times, they don't reach proper operating temperature" so I believe OK. Have not conducted water spray test...

Yes fuel pressure remains over 100psi.

Oh and cleaned RAVE vales also both were pretty good.

Be great to hear from "Mr Di"

 

[68ragtop]

How about just DI enthusiast?

Want to touch on a bunch of things from your posts that are all important, but in a random order.

The battery voltage, still doesn't seem quite up to snuff. It should really make at least 13 volts at idle. The ski will give the maint warning if the voltage drops below 12.5v, or rises above 15v. Anything in-between & it will be happy, BUT under 13 running is low & close to giving you trouble. Keep in mind 12.5V is what a charged battery should have. under 12.5 would actually be a considered discharged/ing. You should be making close to 14 volts by 5000 rpms on the trailer.

Also, your engine should idle at 1450 on the info center, fluctuating very little (1400-1500) regardless of if its in the water or on the trailer. What is your idle speed on the trailer when checking your voltages?

Limp mode is not normally intermittent. Its basically like a rev limiter, & should be accompanied by the "maint" warning. 4500-ish RPMS is the max in the mild limp mode. severe limp mode is idle speed only. Only way out of limp mode is by pulling the lanyard & restarting, so if its intermittent while running, its not in limp mode.

As far as your fuel pressure. 117 is actually a little high. Once the pressure has dropped back to zero, does it show 27 when you put the key on? When you start it, are you seeing 117 as the peak of the needle "vibration"
If so, look close again when its running. you want the number that is centered in the range of the needle vibration. It will smoothen out some like you mentioned when you rev it up, and at that time the pressure should creep up past 107 "IF" you have a healthy air pump. But still read the center of the vibration range.
Its also possible that your gage is off a fuzz. I have a pile of gages & it doesn't take much to have them out of whack.

I skimmed through the posts & never heard what this engine has for compression. To properly check it, install the gage, install the lanyard, hold the throttle to the bars & crank it until the needle stops going up. Ideally you will have 140-145 per side.

Let us know on all of these things, & hopefully we can figure out what to test from there.

 

[G&J]

Hi

Thank you DI enthusiast

OK I went out and bought a compression tester and borrowed a fluke multimeter to make sure I get accurate readings.

Compression front cylinder: 140
Compression rear cylinder: 145

Engine idle: Fluctuating a LOT, center of fluctuation would be around 1450 but drops as low as 770 and goes as high as 2030 as it recovers.

Note: If I rev the unit the revs smooth out as they increase (on the trailer) this has improved somewhat after finding some corroded connectors and cleaning them.

At start of tests battery: 12.4 volts. During idle battery voltage increased to only 12.5 volts... Red light & maint appears...
Briefly charged battery: 12.6 volts. During idle battery voltage increased to only 12.8 volts... NO red light or maint...
Note: New battery.

Fuel pressure: 27 when key 'on'. Sorry 107 is closer to the mark... 117 mistype Note: Fuel pressure does steady with revs and also fluctuates inline with revs as above, dropping low when revs are low and rising to correct level as revs increase.

As I have the wizbang multimeter I thought I would re-do some resistance checks;
Stator 2 windings = .5 ohm. 1 winding = 1 ohm (slightly different). Also measured (attempted) stator AC volts and could not get accurate reading (10 volts across one winding? Via meter leads down the back of plug).

Weirdly I did previously get good voltage readings from stator? Crappy connector?

Now looks like stator is faulty (any better way to test other than attempt to buy the parts and make break out cable tester?) and maybe all along dirty/crappy injector?

Appreciate your thoughts and suggestions. Thank you.