Another GTX Di

[G&J]

Hi

Brand new to the PWC arena... bought 2 x PWC - Yamaha XL700 and Sea Doo GTX Di.

Got a couple of issues with the GTX Di. I have read all the relevant posts I could find and can't find one that that specifically fits and would appreciate feedback / comments on the following....

2002 GTX Di

At idle (running on either cylinder) unit does not run smoothly. The inline fuel pressure gauge (a previous owner fitted) at rest is around the figure I have seen quoted in the forums but when running fluctuates from around 80-90'ish (hard to read) to the correct pressure around 107 PSI.

On the water the best wording to use is it burbles (sounds like it's misfiring and won't go more than 20 mph) the "warning" light came on at one point, but it was not I believe in limp mode. Can't get in to see a mechanic till the end of Jan 2016 for reading of error and what follows...

Before taking for a run had a service - old fuel drained and replaced, new plugs fitted, inline filters cleaned and all bits n pieces visually checked.

Thoughts anyone? I'm looking for a simple magical fix that will enable me to be the hero dad for the Christmas holidays Alternatively I suppose I will have to wait for the expert to have a look next year.

Thanks in advance every one.

G & J

 

[SabrToothSqrl]

well, the good news, it kind of runs, the bad news is the DI is an expensive tricky beast.

I believe it actually idles on one spark plug, so I'm not sure how you did your idle test...?

Generally speaking, from what I've read here, it's your $600 fuel pump that fails and causes these to run poorly or not at all.

 

[tkarvelis]

Check your charging voltage. I have a 2002 GTX that I purchased Thanksgiving that has the same issue. My fuel pressure holds if I run the RPM up to 2000 RPM. My battery voltage will hold about 12.2 if my RPMs are up, otherwise the voltage drops just under 12.

I have a regulator due to arrive tomorrow, so I hope to put it in Sunday and see if that fixes it. If not, I am looking at a scanner to test.

Fo me the previous owner replaced the fuel pump and regulator, but left the original in it, and strapped it on the battery bracket.

You can get a replacement from High Flow, and guys on here have had luck with them.

http://www.seadooforum.com/showthre...el-Pump-Replacement-Guide&highlight=high+flow

 

[mikidymac]

What was the "warning" message that was showing. The DI skis take a lot of power and a marginal or cheap battery can cause the exact symptoms. If there is any question on the battery replace it first.
After that the next common part is the voltage regulator as tkarvelis stated.

 

[jhjesse]

I would rule out voltage/battery first.
I would have the battery load tested. Before having it load tested check the voltage across the battery terminals with ski running at approx. 5000rpms. Anything under 13.5 or over 14.5 indicates the rectifier is bad.
Next I would pull the fuel pump and clean it really good, then replace both fuel filter socks. I can't remember the part numbers off the top of my head, but there is several threads that will tell you.

 

[lamajama]

If you plan on keeping this, give yourself a Christmas present and get a Candoo programmer. It will
pay for itself a lot quicker than you think. And almost always it's the battery, the rectifier (replace with a 4tec version) or the fuel pump.

 

[jhjesse]

+1 ^ on the above. I have 2 DI,s. One has a 4tec rectifier and the other has an OEM rectifier. No problems with either.

Fuel pressure should be 80psi plus 27psi air pressure equaling 107psi. When you get to the fuel pressure install a pressure gauge on the hose coming from the air compressor. It should build to 27 psi.

I also cut out the very expensive inline fuel filter and replaced it with a wix 33032 inline filter and two heavy duty stainless steel hose clamps. Now I can change the fuel filter easily and inexpensively. Works great.

 

[Sportster-2001-951C-Stock]

I agree, check the battery voltage before and during running. Before startup the voltage should be no less that 12.5V and if less this indicates a problem with battery being undercharged or defective.

Also remove the spark plugs and replace them with fresh new ones, this is always the first course of action with 2-stroke engines when they seem to be running roughly. Inspect and diagnose the used spark plugs for common signs of trouble before continuing to run the engine, the color of the ceramic insulator is important.

There are several common issues that can cause rough running, mechanical and electrical. One of the biggie electrical issues is a corroded battery cable connector in the e-box where the ignition coils are mounted.

Also it's common for the electric fuel pumps in these to become weak due to pump corrosion that occurs due to lack of usage (sitting around for long periods unused).

The cylinder compression should be in the neighborhood of 135~145psi, this is a metric for monitoring mechanical engine health.

 

[tkarvelis]

Well for mine it is not the regulator. I replaced it with the one of the OSD 4tec units, and I have the same issues low charging voltage.

I know the stator creates the AC voltage, but I do not know what voltage should be between each terminal, but I would suspect it should be around 30 to 40 vac with a 1/2 wave rectifier and voltage regulator needing around 15 vdc to regulate properly. I will need to measure this after the new year when I can work on the ski again.

I measured the resistance between the three yellow wires. The first one is an open between the other two. The second and third wire have about .1 ohms between them.t

It looks like I need to pull the stator as it appears that the three wires go directly there based on the service manual.

Before I do that, I am going to check the grounds in the E-Box since pulling the stator does not look to be fun.

 

[Minnetonka4me]

Aftermarket regulators suck. Plain and simple. Id get an OEM before I took it all apart.

 

[G&J]

Hi All

Sorry for not responding earlier, been away...

I will strip down the fuel pump first I think and have a look at the filters.

Thanks for the comments and suggestions.

 

[Coastiejoe]

I will third the Candoo Pro. They are great to have. But with the DI ski, they are nearly required equipment...

 

[Mickirig1]

I have a Hanes fuel injection repair manual. It covers most fuel injection systems no matter what they are in. The biggest thing is voltage to the fuel pump. All electric fuel injection pumps need the correct voltage and amp flow period, it states. That would be a first place to look / start. Without the correct pressure and flow, it is not going to run right.

 

[68ragtop]

Fuel pressure should be 80psi plus 27psi air pressure equaling 107psi. When you get to the fuel pressure install a pressure gauge on the hose coming from the air compressor. It should build to 27 psi.

Jesse hit it on the head here. If you have a pressure gauge in line & your dropping under 107 when running, you have a fuel pressure problem. Could be the pump, could be the air compressor, but if your pressure is dropping to 80, there a problem there. The gauges are hard to read because the air compressor pulses make it bounce. As you bring up the RPMS, it should get smoother, but the needle will always look like its "vibrating" Look at the center of its variance & that will be close.

107 at idle is a must. When you rev up the machine from idle, the norm would be for the pressure to actual rise a little past 107 & not drop below.

DI's do idle on both cylinders, but if one cylinder isn't firing, it will try to speed up & compensate for it. They idle pretty well on one lung, but do use both.

 

[Sportster-2001-951C-Stock]

I measured the resistance between the three yellow wires. The first one is an open between the other two. The second and third wire have about .1 ohms between them.t

You have an open leg of your stator, not gonna keep up with the electrical power demand that way. 0.1 sounds a bit low between the other two but that's a moot point.

 

[G&J]

Hi All

Finally got time to have a look Pulled the fuel pump out for a quick visual inspection, filters all OK. On re installation checked fuel pressure also OK based on feedback above.

Next (hopefully tomorrow) check battery voltages "check the voltage across the battery terminals with ski running at approx. 5000 rpms. Anything under 13.5 or over 14.5 indicates the rectifier is bad. "

If OK - Then run individual cylinders at a time to see if the (what I called like misfiring) occurs on both cylinders or one only.... If both and voltages OK I am lost... Battery?

If one cylinder only next check ignition coil then air/fuel injectors.

Sound like a plan?

 

[G&J]

Sorry... post sent twice? edited...

 

[Sportster-2001-951C-Stock]

13.5V is a little low by a few tenths I think, but wouldn't surprise me given the fuel pumps and injectors are power hogs. I'd be concerned if over 14V I think, FWIW my carbed 951 regulates to 13.8V

If there's something wrong with the charging circuit, this will mess with the engine computer and CDI ignition.

Can you do a compression test? If compression is down in one cylinder you can throw all kinds of money at the wrong things and still it won't run.

The throttle position sensors are a common issue with age, use an analog volt or ohm meter and look for dead spots in the potentiometer, especially around low throttle position. You'll see the needle jump to zero suddenly if defective.

Someone may have swapped connector cables and reconnected to incorrect sensor by mistake, usually all around doesn't run well if at all in this case. Check electric schematic and confirm wire color codes, is the quick method.

Since you had the fuel pump module out, you should pressurize check the fuel tank to make sure the pump module gasket doesn't leak, seen several photos of skis blown apart and people injured as a result of leaking fuel around the fuel pump module.

 

[G&J]

Ok...... hooked up the multi-meter to the battery....

At idle hovering around 12.8v at revs only goes to 13v - therefore regulator stuffed?

Ebay best / quickest place to get a replacement?

 

[Sportster-2001-951C-Stock]

13V is maybe not too bad considering the battery was probably still recharging from the cranking. What was the voltage before startup at least 12.5?

A good battery will measure at least 12.5, more like 12.7 after sitting overnight (12 hours). If not, the battery is either discharged or defective.

Be sure your battery is good, many problems are caused by a bad battery.

If the voltage was less than 12.5 (not charging) or greater than 14 (overcharging) then we could say the regulator isn't working.

OSD parts has regulators, or [MENTION=41828]Minnetonka4me[/MENTION] has them and he knows which ones work correctly (probably go with the 4-TEC upgrade).

Here's a little more info, for converting a carbed 951 internal regulator to external type. This is using the proven heavy-duty 4-tec regulator. You shouldn't need this full conversion harness but make sure the replacement is connector-compatible.
http://www.seadoosource.com/947rectifierupgrade.html

 

[G&J]

Thanks for your thoughts...

It looks to me, given your comments above, that the regulator is OK... therefore I am back to square one what to check next...

I just pulled the plugs they both seem to have carbon fouling? Could this be an indication of the cause of the problem? Help please :-(

 

[Sportster-2001-951C-Stock]

Yeah, I'm more concerned about your battery than the regulator.

The plugs will foul pretty quickly when running on trailer and short run times, they don't reach proper operating temperature with no load and idling thus carbon soot fuel deposits aren't burned off.

Also, if you have a leaking fuel injector, that cylinder mixture will be too rich and lead to lack of piston lubrication due to oil dilution by excess fuel. You might notice the plug fouls too often.

A quick check for a leaky fuel injector I use is by watching fuel pressure decay after the fuel pump shuts off. If the pressure holds pretty well (sometimes up to 30 minutes but 10 minutes is good) then you can feel confident one of the injectors isn't peeing fuel into the cylinder and the pressure regulator is holding pressure.

Another way is to remove the fuel rail with injectors in then power the fuel pump and look for one that's dripping fuel. A quick crank (plugs out, wires grounded) and they should squirt fuel, you can see the spray pattern (I use a rag to catch the fuel).

A NOID light plugged into the injector harness connector tells you is the injector is being pulsed. Usually you can feel the heat or lack of heat on one cylinder to identify if one cylinder isn't firing.

Having a set of fresh plugs handy is always the first place to begin when a 2-stroke isn't running correctly, I see more fouled plugs than anything else.

 

[68ragtop]

Is the maint warning still coming on like you mentioned in your original post? Or is it running bad with no info center warnings? That ski will trip the maint light if the voltage is too high, or too low every time. When the electronics side of the ski is happy but its running poor it's most likely going to be fuel, air, or a compression problem. Those are the three things the electronics do not monitor in any way. But, If it is running bad because of those issues, its possible to trigger the maint warning if the sensors are giving readings way out of whack. For example the fuel system is not delivering enough fuel off idle & your holding the throttle further open to try & compensate. The combination of high throttle position & low RPM crank speed can trigger a warning. But the warning is ultimately created by the fuel pressure.

You said your fuel pressures are good. Are they staying true when the engine is acting up. I have found healthy air/fuel systems with be able to create the combination of 107 PSI fuel at engine cranking speeds within just a few seconds of cranking with the plug wires off. If it climbs slowly, or dips when you crack the throttle something is amiss.

The cylinder compression should be in the neighborhood of 135~145psi, this is a metric for monitoring mechanical engine health.

Also, Did you find compression in the range like sportster asked about in post #8 Be sure to hold the throttle to the bars during the test to turn off the injection system during cranking.

 

[G&J]

Thanks Guy's

Thanks again for your assistance, OK here we go...

1.
a. PWC off for over 10 min fuel pressure gauge reading 25
b. Turn PWC on, starts immediately, idles roughly, seems to hunt and miss a little (revs up a bit slows down sounds like its missing at times) fuel pressure all over the place bouncing from about 75 to 100 ish... in sync with hunting - missing...
c. No MAINT on display or red warning light

2.
a. Rev PWC fuel pressure sits around 107 with minor vibration of needle, units almost immediately starts to "miss" fuel pressure again bouncing all over the place smaller range this time but again in sync with the "missing"
c. MAINT now on display and red warning light on

3. Dot the I cross the T lets do this again before posting...
a. Start... clicks once wont start MAINT light on...
b. Measure battery voltage 12.5V
c. Plug in "key" again battery drops to about 8V when "pump" pressurizes fuel line
d. Start... clicks once wont start MAINT light on...
c. Measure battery voltage 12.5V
d. mmmm try again...wont start a few times like above... then kicks over and 1 & 2 above occurs..

I'm off to buy a new battery before I do anything else me thinks...

 

[tkarvelis]

Take the battery with you and have them test it. Next time the ski is running measure the voltage. Is should be 13 to 14 volts. My gut is telling me it is not charging. I have an 02 that has an open coil, and will not charge. Your description is spot on. I pulled the engine to rebuild.